*Article* **Comparison between Two Strategies for the Collection of Wheat Residue after Mechanical Harvesting: Performance and Cost Analysis**

#### **Alessandro Suardi 1, Walter Stefanoni 1,\*, Simone Bergonzoli 2, Francesco Latterini 1, Nils Jonsson <sup>3</sup> and Luigi Pari <sup>1</sup>**


Received: 25 May 2020; Accepted: 12 June 2020; Published: 17 June 2020

**Abstract:** The growing population worldwide will create the demand for higher cereal production, in order to meet the food need of both humans and animals in the future. Consequently, the quantity of crop by-products produced by cereal cropping will increase accordingly, providing a good opportunity for fostering the development of the sustainable supply chain of renewable solid fuels and natural feedstock for animal farming. The conventional machineries used in wheat harvesting do not guarantee the possibility to collect the chaff as additional residue to the straw. The present study investigated the possibility to equip a conventional combine with a specific device, already available on the market, in order to collect the chaff either separately (onto a trailer), or together with the straw (baled). The total residual biomass increased by 0.84 t·ha−<sup>1</sup> and 0.80 t·ha−<sup>1</sup> respectively, without negatively affecting the performance of the combine when the chaff was discharged on the swath. Farmers can benefit economically from the extra biomass collected, although a proper sizing of the machine chain is fundamental to avoid by-product losses and lower revenue.

**Keywords:** biomass; bioenergy; straw; combine harvester; chaff; by-product

#### **1. Introduction**

#### *1.1. Framework*

The use of non-renewable sources for meeting the fast-growing energy demand worldwide could trigger negative effects on the environment in terms of pollution. On the other hand, as the worldwide population is expected to exceed 9 billion people by 2050 (FAO), the production of several key commodities will also increase accordingly, in order to meet the fast-growing demand for food. The production of cereals is expected to grow from the annual 2.1 billion tons up to 3 billion tons by 2050 if animal feeding is also included [1]. Consequently, the ongoing conflict on land use for food and non-food crops will be more serious if new strategies are not promptly undertaken. Regarding the bioenergy production, the European policy is keen to promote the utilization of agroforestry residues over the plantation of energy crops [2], by applying stringent regulations, in order to meet the climate and energy targets set in the EU 2030 framework [3,4]. Hence, a possible strategy could be improving the collection and the utilization of residual biomass that is normally produced in cereal cropping, but not effectively exploited yet [5]. During the harvesting of cereals, for example, in addition to the collection of grains, a large quantity of residual biomass is usually produced as straw and chaff. Among them, straw has been exploited for a long time as natural bedding for animals [6] and, recently, as a valid source for energy production or as raw material for industrial processes. In terms of energy, one hectare of cereal straw is approximately equivalent to 200 L of oil [7] if considered as solid biofuel. However, the biochemical properties of ligno-cellulosic materials, as straw, make it suitable for further industrial processing. For instance, Fang and Shen [8] reported the suitability of straw for paper and paperboard production, Hýsek et al. [9] highlighted the possibility to exploit cereal residues for composite material production, while Swain et al. [10] investigated the hydrolyzation of cellulose and the hemicellulose of straw into fermentable sugars, which are particularly attractive for bioethanol production industries. Recently, it has been found that winter wheat straw can be returned to soil as biochar to enhance the yield in corn and peanut cultivation [11]. Conceptually, the development of a comprehensive, efficient and sustainable straw supply chain can bring benefits to many sectors and to developing countries as well [12].

On the other hand, the chaff, as the finest part of the grain residue, is normally lost on the ground after mechanical harvesting. In wheat crops, chaff is available at the rate of the 17% of the grain yield [13], and if considering the European annual production of wheat and spelt estimated in, approximately, 138 Mt [14], the whole European biomass supply chain could benefit from the collection of 23 Mt·yr−<sup>1</sup> more of biomass. This would contribute to increase the availability of solid biofuel for the production of energy, particularly if baled with the straw [15]. Chaff palletization is also possible, but only if provided as loose product [16], as well as for the production of second generation bioethanol [17].

Nevertheless, the collection of chaff has already been investigated in agriculture, as a promising tool in organic farming of cereal grain for reducing the accumulation of weed seeds in the soil over time [18,19]. In Australia, different mechanical devices were invented and tested on field, with the specific purpose of removing the chaff for decreasing the amount of weed seeds [20–22]. The chaff was then arranged in small hips or in narrow strips for being burnt afterwards. The possibility to collect chaff for purposes different from weed seeds control, has already been investigated under the economic aspect by Unger and Glasner [23], whose study revealed that the exploitation of that kind of residue is feasible. Although the simultaneous harvesting of wheat grains and chaff has been recently investigated [19,24–26], the literature still lacks of specific data from in-field experiment.

Actually, mainly due to the lack of knowledge on the specific devices already available on the market, uncertainty on the harvesting system to adopt and due to the lack of a dedicated supply chain for an effective exploitation, the chaff still remains an untapped biomass. There is a real need to evaluate the cost effectiveness and the performance of systems for harvesting chaff in order to foster the utilization of this biomass, depending on the final use, and to stimulate the development of a dedicated value chain. According to this, the aim of the study consisted in filling this knowledge gap and providing a deeper understanding of the possibility to enhance the current wheat harvesting method, in order to improve the quantity of biomass collected, including the chaff.

#### *1.2. Main Cha*ff *Utilization*

The chaff from cereal crops can be handled differently according to its final utilization. More recently, the chaff is thought as a source of biomass for energy use, but others are known in literature. For instance, in Australia, harvest weed seed control (HWSC) systems have been developed and tested for years, providing good results in terms of alternative strategy for weeds control. Walsh, Newman, and Powles in 2013 [20] reviewed the following systems: chaff chart, narrow windrow burning, bale direct and Harrington seed destructor (HSD). The first two of them accumulate the chaff, either in heaps, or in a narrow windrow (50–60 cm wide) on the field for direct burning. Among the other two systems, apart from the HSD that mechanically destroys the seed weeds, the direct baling strategy provides multiple choices for chaff utilization. In fact, the chaff is baled with the straw as soon as they exit the cleaning shoe of the combine harvester. Indeed, baling them addresses two main problems: the removal of weed seeds and the collection of biomass for livestock (both feeding [6,13]

and natural bedding). The presence of chaff into straw bales also increases the adsorbent capacity of natural bedding [27]. Even poultry farming can benefit from loose chaff availability on the market. A direct interview with a local farmer in France highlighted the positive effects, noticed by farmers, on the welfare of the animals that could scratch around in search for broken kernels and weed seeds, which, in turn, contributed to overall feeding. The same experience was reported by Italian farmers. The use of similar cereal residues is reported in literature as a valid source for littering. Anisuzzaman and Chowdhury reported that rice husk was a good litter material for rearing broilers [28] and it also has a high adsorbent capacity if compared with sawdust [29]. Chaff could also be suitable for further processing, like briquetting, and used for multiple purposes. Akerlof [30] reported the possibility of producing briquettes of soybean chaff for meeting the needs of livestock in providing complete feeding, whereas spelt chaff has been proven to be a good raw material for the production of briquettes for non-feeding purpose, who exhibited different mechanical properties according to the temperature of compression applied [31]. Wheat chaff applications are not fully studied in the sense of both feeding or not-feeding purposes. The unviability of specific mechanical machines able to collect it without increase in the harvesting costs, has probably limited the research in that direction. For this reason, this study addresses an important issue for the development of new production chains based on cereal residues, showing two possible chaff collection logistics, the limits and operating costs of the technologies used, laying the foundations for the development of possible supply chains that are currently underdeveloped or, in some cases, non-existent. In the framework of the H2020 AGROinLOG project [32], a specific test in the Halland region (Sweden) was carried out, to provide evidences on the possibility of improving the conventional supply chains in wheat harvesting, for increasing the overall residual biomass collectable in the field. Specifically, the aim of the test was to evaluate if it is possible to accomplish such a task by equipping a conventional harvester combine with a dedicated device for chaff recovery, already available on the market and manufactured by the Thierart firm (Thierart, Le Châtelet-sur-Retourne, France) [33]. The device permitted one to flow the chaff, either onto a towed trailer, or on the straw swath produced by the combine harvester. Therefore, both chaff collection methods were tested: loose in a towed trailer (CoT), or baled together with the straw (CoS). The trailer was connected to the combine harvester, therefore no tractor was required for towing it. The amount of biomass potentially collectable as grains, straw and chaff was quantified, as well as the performance and quality of the work of all machines involved in the two supply chains. The loss of seeds, straw and chaff were recorded and an evaluation of the harvesting operating costs was carried out.

#### **2. Materials and Methods**

#### *2.1. Field Site and Experimental Design*

The test was performed at Lilla Bösld (Halland region, Sweden) (56◦35 48" N 12◦57 33" E) in the 35th week of 2019 (Figure 1). The field, 15 m a.s.l., exhibited a negligible value of slope.

The wheat (*Triticum* spp.) variety "Julius" was sown in medium clay soil type (24–29% of clay) in September 2018, with a seeding rate of 220 kg·ha−<sup>1</sup> and cultivated in conventional farming. Fertilization was carried out with 150 kg·ha−<sup>1</sup> of PK 11–21 and 500 kg·ha−<sup>1</sup> of Nitrogen fertilizer (27% N <sup>+</sup> 9% SO3) and 200 kg·ha−<sup>1</sup> of calcium nitrate. For the weed control 1 L·ha−<sup>1</sup> of MCPA and 15 g·ha−<sup>1</sup> of Express 50 (wetting agent 0.1 L·ha<sup>−</sup>1) were used. For the fungus control, 0.5 L·ha−<sup>1</sup> of Ascra Xpro was applied.

Within the field, a homogeneous area of 3 ha was preliminarily selected. The surrounding wheat was harvested and the whole biomass removed, in order to avoid edge effects and biased measurement. The selected area was then divided into three blocks, each of them sub-dived in two rectangular shaped plots measuring approximately 0.5 ha. Thus, three random replications per treatment were obtained, for a total of six plots. The chaff was collected in two different ways (treatments): either discharged on the swath (CoS) or collected on a trailer (CoT).

**Figure 1.** Map of the experimental field in Halland region of Sweden.

#### *2.2. Pre-Harvest Tests: Theoretical Biomass Assessment*

For management reasons, the test was split into two consecutive days: the first day was dedicated to the pre-harvesting activities and combine harvesting; the following day occurred the baling operation and post-harvesting activities. Before harvesting, the whole plants of 10 samples areas of 1 m<sup>2</sup> randomly chosen were hand harvested. Culms and spikes were weighed separately. Successively, all spikes and a representative sample of culms were put in sealed bags and shipped to the laboratory of Research Centre for Engineering and Agro-Food Processing (CREA) for further measurements as: theoretical yield of grain and chaff, dry weight and moisture content.

In the laboratory, by using a stationary thresher (PLOT 2375 Thresher, Cicoria Company, San Gervasio, Italy), kernels were separated from the rest of the spikes (rachis, lemma, glumes and palea). The dry weight and moisture content of culms, kernels and chaff was assessed according to the EN ISO 18134-2:2017 [34] standard.

#### *2.3. Equipment*

The contractor provided all the machines required for the test. Settings of the combine harvester, as well as the baler, were maintained at a constant rate throughout the experiment.

#### 2.3.1. Combine Harvester and Recovery System

A combine harvester New Holland TX68 with a conventional threshing drum, straw walker and cleaning shoe was used to perform the test. The header was 7.27 m width and it was specifically designed for cereal harvesting. The machine was driven by a 209 kW diesel engine and the chassis was comprehensive of a dedicated hitch for trailer towing.

The device for the chaff recovery was installed at the end of the cleaning shoe of the combine harvester. As shown in Figure 2, the device is made of a tank that receives the chaff from the cleaning shoe; within it, there is a steal-made screw that delivers the chaff to the two-stage turbine which, in turn, blows it through the outlet. According to the company Thiérart [33], the device requires a minimum of 45 L·min−<sup>1</sup> of hydraulic oil flow rate to work properly and the cutting bar of the combine harvester should not exceed 5.5 m in width to properly manage the chaff flow.

**Figure 2.** Device developed and patented by Thierart for chaff recovery: (1) two stages turbine; (2) specific support for the installation; (3) access hatch to the screw for inspection (source: https://www.menuepaille.fr/materiels/turbine-a-double-etage/).

Here, a PVC pipe is connected, in order to permit the discharge of the chaff, either on the swath (Figure 3a) or onto the trailer (Figure 3b). The screw and the twin-stage turbine are driven by the dedicated hydraulic system.

The trailer used was a single-axed wagon, with a pivoted drawbar directly connected to the hitch of the combine (Figure 3a). The loading capacity of the trailer was 6 m3. The upper part of the trailer was closed with a thick plastic film, in order to prevent accidental loss of chaff due to wind interference. The combine harvester was also equipped with auxiliary hydraulic connections, for controlling the movements of the trailer while discharging the chaff.

**Figure 3.** (**a**) Loose in a towed trailer (CoT) = chaff recovery system mounted in New Holland TX68, for the discharging of the product on a towed trailer (Trailer Agrohill Maskin AB, Halmstad, Sweden); (**b**) CoS = chaff recovery system mounted in New Holland TX68, for the discharging of the product on top of the swath.

#### 2.3.2. Residual Biomass Harvesting

In treatment CoT, the chaff collected during the harvesting was systematically discharged into an auxiliary trailer parked outside the field, then weighted at the end of every plot, using a local scale. In both treatments, the straw were baled using a round baler John Deer 550 towed by a tractor John Deere 6830. The baler was completely empty at the beginning of each plot. At the end of each experimental unit, the machine was forced to close the bale, even if undersized. The last bale was included in the calculation of the residue production per plot, but not in the calculation of the mean weight of the bales, in order to avoid biased mean weights. In treatment CoS the straw swaths, that also included the chaff, were baled, according to the same methodology applied in CoT. In both treatments the fuel consumption registered by the on-board computer of the tractor was recorded for a fuel consumption calculation.

#### *2.4. Harvesting and Baling Performance*

Every plot guaranteed the formation of four swaths after harvesting, with minimal overlapping between the passes. In treatment CoT, the combine had to stop at least once, in order to empty the trailer and complete the harvesting. At the end of the plot, the trailer was emptied again for total chaff weight. The time required for discharge operations was recorded as accessory time. To measure the grain yield, the collected grain was discharged on a trailer and weighted for each plot.

The performance of the machines was evaluated through the study of the working times, performed according to the Comité International d'Organisation Scientifique du Travail en Agriculture (CIOSTA) methodology and the recommendations from the Italian Society of Agricultural Engineering (A.I.I.A.) 3A R1 [35]. The evaluation of the field speed allowed the determination of the theoretical field capacity (TFC, ha·h<sup>−</sup>1), the effective field capacity (EFC, ha·h<sup>−</sup>1), field efficiency (FE, %) and material capacity (MC, t·h−1). Gathered data were used to define the performance of the machines and the operative costs. Fuel consumption during baling was recorded by using the measuring system of the tractor. In the following paragraphs, the biomass unit (t) refers to fresh weight.

#### *2.5. Post-Harvesting Test: Biomass Collected, Losses and Bulk Density*

After baling, all bales produced within the plots were weighed singularly for total biomass baled assessment and average fresh weight measurement (here, the last bale was not included in the calculation). In treatment CoT, the quantity of the chaff collected was determined by weighing the chaff collected in each plot on an in situ scale.

Losses of biomass were assessed for stubble, straw and chaff. By knowing the cutting height of the combine header, stubbles were reconstructed in the laboratory by cutting the basal part of culms previously harvested for pre-harvest analysis. Straw and chaff losses were determined as the difference between the theoretical biomass available derived from the pre-harvest analysis and the effective biomass weighted at the end of the test. The moisture content of each biomass fraction was measured according to the standard methodology described above. The bulk density (kg·m−3) of the loose biomass stored in the trailer was assessed by taking 10 randomly selected samples of chaff and was measured according to ISO 17828:2015 [36]. In each plot, all bales were weighed singularly, and three of them were randomly selected and their sizes measured for volume assessment. Bulk density was successively calculated by dividing the mass in kilograms by the volume in cubic meters.

#### *2.6. Cost Analysis*

In the economic analysis, the following parameters have been taken into account: purchase and operating costs that were provided by the contractor via a interview, performance of the machines derived from the field tests as primary data, and standard values reported in CRPA methodology [35]. Hourly costs of machines were calculated on the basis of the market value of the agricultural machinery [37,38]. The prices of the machines have been discounted to 2019, applying the lending rate of 3% provided by Banca d' Italia Institute [39]. The parameters used during the cost analysis are reported in Tables 1 and 2.


**Table 1.** Parameters used for the economic analysis in CoT treatment. Harvesting stage with the collection of chaff on a towed trailer and straw baling stage.

**Table 2.** Parameters used for the economic analysis in baled together with the straw (CoS) treatment. The chaff collected with the twin-stage turbine is discharged on the swath and baled afterward.



**Table 2.** *Cont.*

In the calculation of the operating costs of the two harvesting systems, the time required for each operation, the quantity of the products obtained and the respective market value (Table 3) were considered. The economic allocation in each treatment was derived from the ratio between each product revenue on the total revenues obtained, as shown in the following formula:

$$E\mathbf{a}^{\top} = \frac{M\mathbf{p} \times \mathbf{Y}\_{\mathbf{i}}}{\sum\_{\mathbf{i}=1}^{3} R\_{\mathbf{i}}} \tag{1}$$

where:

*E*a = Economic allocation of each product or co-product (i.e., grain seed, straw, or chaff) per harvesting phase (combine harvesting or baling)

*M*p = Market price of each product or co-product (i.e., grain seed, straw, or chaff)

*Y*<sup>i</sup> = Yield of each product or co-product (i.e., grain seed, straw, or chaff)

*R*<sup>i</sup> = Revenue obtained by multiplying *M*p × *Y*<sup>i</sup>

**Table 3.** Economic allocation used for the cost analysis of straw and chaff harvesting with the Thierart technology in Sweden, for each harvesting phase, and treatment.


Note: prices retrieved from Camera di Commercio di Modena (2019) [40].

#### *2.7. Statistical Analysis*

The statistical analysis was performed in order to discriminate the differences among the treatments. All data were subjected to the analysis of variance (ANOVA), using the R 3.6.1 to separate statistically different means (*p* ≤ 0.05) [41].

#### **3. Results and Discussions**

#### *3.1. Biomass Fractions*

The results of pre-harvesting highlighted that the total aboveground biomass was 18.8 t·ha−1. Spikes represented the 57% (10.78 t·ha−1) of the total (47% seeds and 10% chaff, corresponding to 8.94 t·ha−<sup>1</sup> and 1.84 [t·ha<sup>−</sup>1], respectively) whereas the whole culms accounted for the 43% (8.02 t·ha<sup>−</sup>1). The moisture content was equal to 14.3% (±9.1), 9.0% (±3.5) and 14.6% (±2.7), for straw, chaff and seeds, respectively. After the harvesting, the different fractions of biomass collected are shown in Figure 4.

**Figure 4.** Effective tons of fresh biomass collected in treatment CoT (**left**) and CoS (**right**). CoT permitted one to collect the chaff separately from the straw, while in CoS, the chaff was baled with straw and considered as residual.

#### *3.2. Performance of the Combine*

The methodologies studied for chaff collection highlighted some differences in the performance of the machines involved. According to what was anticipated by Glasner et al. (2019) [42], the theoretical field capacity (TFC) of the combine did not variate among the treatments, as its speed was constant during the cutting and cleaning processes, although a reduction of 10–25% of cleaning was reported in the study. Despite that, significant differences were found in EFC, FE and MC (Table 4), where the accessory times, like the time required for unloading the wagon in CoT, were included. In fact, the wagon could collect only 6 m<sup>3</sup> of loose chaff and, considering the low bulk density of 41.75 kg·m<sup>−</sup>3, the wagon shortly became full of chaff, forcing the combine harvester to stop and exit the field for unloading the wagon. A similar value of 42.88 kg·m−<sup>3</sup> for chaff bulk density was reported by Bergonzoli et al. [26] and slightly higher values of 56 kg·m−<sup>3</sup> and 62.08 kg·m−<sup>3</sup> were found by McCartney et al. [13] and by Suardi et al. [24].

**Table 4.** Comparison of the performance of the combine harvester among the two treatments. (TFC = Theoretical Field Capacity, EFC = Effective Field Capacity, FE = Field Efficiency, MC = Material Capacity).


Note: (ns) not significant; (\*) Significant at *p* < 0.05; (\*\*) Significant at *p* < 0.01.

In CoT, the unproductive times of the combine harvester were 233% higher than in CoS where the chaff was continually blown over the swath. In fact, as depicted in Table 4, the FE and the MC of the combine harvester were significantly higher when the CoS system was applied. In Suardi et al. [19], TFC and EFC were respectively 3.72 ha·h−<sup>1</sup> and 2.28 ha·h−<sup>1</sup> on average and the combine fuel consumption resulted in 11.8 L·h<sup>−</sup>1.

Different methods for loose chaff collection have been reported in the literature. For instance, Suardi et al. [24] tested a continuative discharging of chaff onto a trailer towed by a tractor side by side the combine; that the system permitted to collect 1.27 t·ha−<sup>1</sup> of loose chaff. Differently, Bergonzoli et al. [26] tested a combine harvester equipped with Harcob system, which had an integrated tank of 9 m<sup>3</sup> in volume for storage of the chaff collected and that the system allowed to collect 0.6 t·ha<sup>−</sup>1. Regardless of the quantity of the chaff collected, neither of them reported negative impacts on the combine performance: the trailer volume available for chaff storage in Suardi et al. [24] was better dimensioned, while the Harcob system allows the simultaneous discharging of grain and chaff, avoiding extra unloading time [26]. For that reason, the unproductive times needed were much lower. Similar tests performed by INRA (Institut National de la Recherche Agronomique) in the frame of the project «Systèmes de Cultures Innovants» and CUMA (Federation Nationale des Cooperatives d'Achat et d' Utilisation de Materiel Agricole) in 2011 and 2012 demodays with similar turbine systems, provided higher results in terms of quantity of chaff collected: respectively, 1.5 t·ha−<sup>1</sup> and 1.15 t·ha−<sup>1</sup> [43,44].

#### *3.3. Performance of the Baler*

Regarding the baling stage, the EFC that includes accessories' times (e.g., turning time and unloading time) was lower in CoS, since a higher quantity of biomass in the swath was to be processed (Table 5). That implied more stops for the discharge of the bales and it also forced the tractor to reduce the speed, in order to avoid overloading of the baler's chamber. In fact, the amount of biomass that the baler could process per unit of time was not statistically different. No significant differences were found regarding TFC. The fuel consumption of the tractor was also recorded and referred to the unit of biomass baled. On average, 1.27 (±0.17) l of diesel fuel was required for each ton of straw baled, regardless of the presence or the absence of the chaff in the bales.

**Table 5.** Comparison of the performance of the baler within the two treatments. MC is calculated taking into account the overall quantity of residual biomass produced: straw and chaff together (TFC = Theoretical Field Capacity, EFC = Effective Field Capacity, FE = Field Efficiency, MC = Material Capacity). No statistical differences were found between treatments.


Note: ( † ) Material Capacity refers to tons of fresh residues. (ns) Not significant; (\*) Significant at *p* < 0.05.

Similar tests were performed by Suardi et al. in France in 2018 and 2019 [24], on baling the straw with chaff. The authors reported higher values for TFC, EFC and MC, respectively: 5.23 (±0.65) ha·h<sup>−</sup>1, 3.46 (±0.28) ha·h−<sup>1</sup> and 20.79 (±0.7) t·h−<sup>1</sup> in 2018; whereas 4.64 (±0.31) ha·h<sup>−</sup>1, 3.09 (±0.13) ha·h−<sup>1</sup> and 20.20 (±2.0) t·h−<sup>1</sup> in 2019. When chaff was not included in the bales, the performance of the baler was not statistically different. The fuel consumption ranged between 0.77 (±0.15) l·t <sup>−</sup><sup>1</sup> and 0.94 (±0.12) l·<sup>t</sup> −1 in the case of straw and chaff baling, while it ranged from 1.01 (±0.13) l·t <sup>−</sup><sup>1</sup> and 0.64 (±0.23) l·t −1, when the chaff was dispersed on the ground. In similar experiment, the TFC and EFC of straw baling operation resulted on average 3.96 ha·h−<sup>1</sup> and 2.01 ha·h<sup>−</sup>1, with a mean FE of 51 % [19].

#### *3.4. Losses of Biomass during the Baling Stage*

The theoretical availability of straw, in the present study, was estimated in 8.02 t·ha−1; in line with other studies such as Suardi et al. [24], where the theoretical straw availability was estimated at 7.39 (±0.73) t·ha−<sup>1</sup> and 8.33 (±0.75) t·ha<sup>−</sup>1, in 2018 and 2019 tests, respectively. Nevertheless, during the present study, the amount of residues baled was on average 3.88 t·ha−<sup>1</sup> and 4.68 t·ha−<sup>1</sup> with CoT and CoS treatments, respectively (Table 6). Therefore, the remarkable differences in the residue harvesting performance can be imputed exclusively to the suitability of the machine chosen by the contractor, to carry on the baling stage. The round baler John Deere mod. 550 used during the test was equipped with a pick-up 1.41 m wide, whereas the straw swath produced by the combine harvester measured 1.74 m in width, on average. Hence, 0.33 m of straw swath could not be collected by the baler's pick-up system in each pass, due to reduced width of the its pickup system (Figure 5). At the end of the baling phase, a large quantity of product was still not harvested in the field (Figure 3).

**Table 6.** Differences in fresh biomass outputs from wheat crop, due to the use of a twin-stage Turbine for chaff collection.


Note: ( † ) In treatment CoT the mean residue value takes into account also the chaff, (-) not performed; (ns) non-significant; (\*) Significant at *p* < 0.05.

**Figure 5.** The narrow pick-p of the round baler (**left**) caused high loss of straw (**right**) along the swath (areas of the swath not reached by the baler's pickup system are highlighted in red).

The estimated average loss of residue after baling was 4.75 t·ha−<sup>1</sup> (4.68 t·ha−<sup>1</sup> for CoS, and 4.72 t·ha−<sup>1</sup> for CoT), corresponding to a loss of biomass of 50% on average, without statistical difference between the two treatments.

Bergonzoli et al. [26] reported a similar value when a combine harvester mounting Harcob system (developed for Maize cob harvesting) was modified and used for collecting the chaff in wheat crops, even if the results were ascribed to the cleaning system of the combine harvester.

Such a level of product losses recorded during the tests exceed the sustainable removal rate of 33% proposed by Unger and Glasner (2019) [23]. For this reason, it could be considered positive from the point of view of soil fertility, even if the economic sustainability is closely linked to the amount of recoverable biomass. Therefore, low collection efficiencies may render the operation of recovering residual biomass economically unviable.

However, the scenarios herein proposed provided differences in both the quantity and quality of residuals biomass collectable from wheat cropping, without affecting the grain yield. Such an aspect is very important; in fact harvesting, along with storage, is the most responsible factor for loss of grains throughout the wheat supply chain [45]. The presence of the chaff included in the bales increased both weight and density of the bales by 7.45% and 7.09% respectively, in comparison with bales free of chaff (Table 6). Increases of 18.0% in bale bulk density, due to the inclusion of chaff, was reported by Suardi et al. [24], when a similar turbine technology for chaff recovery was used. On the other hand, Suardi et al. reported a non-significant increase in the case of chaff admixing performed with a combi system (manifactured by Rekordverken Sweden AB, Kvänum, Sweden) [19].

The different methods studied, allowed to harvest 4.68 t·ha−<sup>1</sup> and 4.72 t·ha−<sup>1</sup> of wheat residues by baling chaff and straw together, or by harvesting chaff in the trailer and straw baling, respectively (Table 6), with no statistical differences.

#### *3.5. Cost Analysis*

In the analysis of the unitary costs, the running cost of each machinery involved in the supply chain is related to the market price [€·t <sup>−</sup>1] of each product and by-product obtained. The performance of the machines contributed to the final calculation of the costs. For instance, the reduction in EFC, FE and MC of the combine harvester (Table 4) found that, when the combine towed the wagon (CoT), it increased the hourly harvesting cost by 3.41%, the cost per hectare by 73.35%, and the cost per ton of biomass processed by 67.73% (Tables 7 and 8), in comparison with CoS. Here, the combine harvester did not waste time to continually stop and unload the wagon.


**Table 7.** Costs for unit of time, surface and ton of biomass processed in CoS harvesting system, considering the productivity and the market price of each product.


**Table 8.** Costs for unit of time, surface and ton of biomass processed in CoT harvesting system considering the productivity and the market price of each product.

On the other hand, when the chaff was blown on the swath, the baler had much more biomass (straw and chaff) to process. In fact, the baler's EFC (Table 5) dropped by 18.23% and the costs per hectare and per ton of biomass processed increased by 21.79% and 101.85%, respectively. The hourly cost for baling did not change (Tables 7 and 8).

The choice to apply CoS over CoT harvesting method affected both the performance and running cost of the machines. According to Table 9, the harvesting cost per hectare increased by 28.90% (from 152.03 €·ha−<sup>1</sup> to 196.05 €·ha<sup>−</sup>1), when the chaff was collected as loose material (CoT).

**Table 9.** Economic calculation cost, revenue and the net gain obtained from the collection of grains, straw and chaff when harvested with the two different methods: CoS and CoT.


The same results were obtained by Unger and Glasner in 2019, where the separate chaff collection and supply led to higher costs [23]. However, the overall capacity of CoT system permitted one to collect more biomass per hectare (0.38 t and 0.04 t of grain and chaff respectively), counterbalancing the higher costs. In fact, if considering just the net gain per hectare, CoS permitted to gain only 27.52 €·ha<sup>−</sup>1.

Furthermore, in the present study, a market price for chaff of 50 €·t <sup>−</sup><sup>1</sup> was considered. However, Unger and Glasner [23] highlighted that the potential revenue of chaff could vary depending the final use and market price that can range from 81 €·t <sup>−</sup><sup>1</sup> to 200 €·<sup>t</sup> <sup>−</sup>1, making chaff separate collection economically viable, and giving the farmer, from year to year, different sales opportunities of the product to more profitable markets.

#### **4. Conclusions**

The cultivation of the cereals is an important source of staple food around the world, and it also produces a relevant quantity of ligno-cellulosic biomass, that can be further exploited in order to improve the economic and environmental sustainability of the whole supply chain. In fact, agricultural residues are gaining more and more interest, due to their considerable availability and their potential content of energy, or as raw material for industrial processes. Cereal straw and chaff collected either separately or baled altogether can be a source of food for animals, particularly in case of shortage, or natural bedding for livestock. In poultry farming, farmers reported positive experiences on the use of loose chaff for littering, since it provides wellness to animals and a good adsorbent capacity. However, possible utilization of chaff is to produce bioenergy. Normally, about two tons of chaff per hectare are available, but still not collected, due to three major problems: unawareness of proper mechanical devices available on the market for its collection, uncertainty on the harvesting system to adopt and the development of a specific supply chain for its exploitation. So far, the literature reports few cases of chaff collection with the specific purpose of weed seeds removal, but it still lacks specific experiments on these machines intentionally used for biomass collection. Therefore, the present study aimed to fill that gap and provide deeper understanding in the possibility to enhance the current wheat harvesting method, in order to improve the quantity of biomass collected by including the chaff. This research analyzed the technical and economic feasibility of two different logistic methods for chaff collection: chaff collected as loose product onto a towed trailer (CoT) and baled altogether with the straw (CoS).

Our results suggest that upgrading a conventional combine harvester with a twin-stage turbine for chaff collection increases the total biomass collected by 0.84 t·ha−<sup>1</sup> without affecting the grain yield. Furthermore, the separation of chaff from the straw is performed simultaneously to the cleaning process of the grain and no additional passes of the machine on the field are needed, and further soil compaction is prevented.

Even if our results reveal that the collection of the loose chaff into a towed wagon is more costly than including it into the bales, the market price of the pure chaff should be higher, to offset the extra costs required by the contractor for the collection and handling. Furthermore, it should be noted that the trailer system could be used also for other crop by-products; for instance, collecting finely chopped roughage after a forage harvester, without the strong modification of the combine, reducing the unitary cost of the investment and increasing the quantity of biomass potentially collectable. In fact, the unproductive time in CoT was 233% higher than in CoS with an increase of 43.94 €·ha−<sup>1</sup> for the harvesting cost. In addition to the higher costs, loss of revenue may take place in case of inappropriate choice of the machine for accomplishing a specific task. Particularly, the round baler chosen by the contractor could not collect all the straw windrowed by the combine harvester. Although the subject is still under discussion, some authors consider that a residue extraction of no more than 33% is sustainable for the soil fertility. On the other hand, however, an amount of uncollected residue, such as that found during the study (50% of harvesting losses), could negatively affect the economic feasibility of the residue collection phase, questioning the investment in specific equipment. In fact, according to 6results from CoT treatment, where the chaff was not included in the straw, only 3.88 t·ha−<sup>1</sup> out of 8.02 t·ha−<sup>1</sup> of straw available on the field were baled. Considering the straw market price of 50 €·t −1, this can be translated into a loss of income of more than 200 €·ha<sup>−</sup>1.

Future studies should be focused on the assessment of the sustainability of the chaff collection, in terms of the effect to the soil fertility, carbon dioxide emissions and soil compaction.

**Author Contributions:** Conceptualization and methodology, A.S.; Investigation and data curation A.S., W.S., F.L.; writing—original draft preparation W.S., S.B.; writing—review and editing, A.S., L.P. and N.J.; supervision, L.P. and A.S.; funding acquisition, L.P. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by European Union's Horizon 2020 AGROinLOG project grant number 727961 (http://agroinlog-h2020.eu/en/home/).

**Acknowledgments:** Authors thank the contractor Leif Jönsson (Tjärby Gästgivaregård Laholm, Sweden) and his team for their valid support and assistance provided during the activities, as well as Sandu Lazar for their valuable contribution in the field activities. Moreover, the authors thank Consuelo Attolico for looking after the relationship with the French company ETS Thierart®.

**Conflicts of Interest:** The authors declare no conflict of interest.

#### **References**


© 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

## *Article* **Postharvest Losses of Pomegranate Fruit at the Packhouse and Implications for Sustainability Indicators**

**Ikechukwu Kingsley Opara 1, Olaniyi Amos Fawole 1,2 and Umezuruike Linus Opara 1,\***


**\*** Correspondence: opara@sun.ac.za; Tel.: +27-21-808-4064

**Abstract:** Pomegranate fruit, like other types of fresh horticultural produce, are susceptible to high incidence preharvest and postharvest losses and waste. Several studies have been done to improve the production and handling of pomegranate fruit to meet market standards, but little has been done in loss quantification, especially in the early stage of the value chain such as the packhouse. Therefore, the aim of this study was to quantify the magnitude of pomegranate fruit losses at the packhouse, identify the causes, and estimate the impacts of losses. The study was conducted on a case study packhouse in the Western Cape Province of South Africa from February to March 2020. The direct measurement method, which involved physical identification of the causes of loss on individual fruit, was used for data collection. Loss quantification involved the calculation of lost fruit proportional to the amount put in the packhouse processing line. The results showed that losses ranged between 6.74% to 7.69%, which translated to an average of 328.79 tonnes of pomegranate fruit removed during packhouse operation per production season at the investigated packhouse. This magnitude of lost fruit was equivalent to over ZAR 29.5 million (USD 1,754,984) in revenue, in addition to the opportunity costs of resources used to produce lost fruit.

**Keywords:** pomegranate; losses; nutrition; environmental; resources; packhouse; postharvest; impacts

#### **1. Introduction**

Pomegranate (*Punica granatum L*.) is an ancient fruit believed to be first cultivated around 3000 and 4000 BC, and was mentioned both in the Bible and the Quran [1]. Its origin is traced to the Middle East, in present-day Iran, and it adapts to a variety of soil conditions in the Mediterranean, subtropical, and tropical climates [2,3]. Currently, it is grown in many countries for fresh consumption and industrial uses [4,5]. As a result, more than 500 cultivars are grown globally, with some cultivars named differently in different parts of the world [2,4–6]. The awareness of its numerous uses and benefits has made it popular among other fruit [5,6]. Pomegranate can be eaten as fresh produce or juiced and stored in the appropriate temperature and relative humidity. It is sweet, sour, or acidic depending on the cultivar and rich in vitamins, minerals, and other organic compounds [4,5]. The consumption of pomegranate has been linked with a great health outcome in different studies [3,7–10]. The phenolic compounds present in pomegranate have been found to be great anti-inflammatory, anti-oxidative, and anti-carcinogenic chemical compounds, which helps to reduce tumour growth and chronic inflammation [11]. The hypoglycaemic activity of pomegranate juice has been found to prevent diabetes mellitus [12]. Pomegranate fruit consumption has been reported to reduce cardiovascular diseases [13]. Chemical compounds in pomegranate fruit are also used in the treatment of diseases such as ulcers,

**Citation:** Opara, I.K.; Fawole, O.A.; Opara, U.L. Postharvest Losses of Pomegranate Fruit at the Packhouse and Implications for Sustainability Indicators. *Sustainability* **2021**, *13*, 5187. https://doi.org/ 10.3390/su13095187

Academic Editors: Alessandro Suardi and Nadia Palmieri

Received: 13 February 2021 Accepted: 26 April 2021 Published: 6 May 2021

**Publisher's Note:** MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

**Copyright:** © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

acidosis, haemorrhage, aphthae, diarrhoea, dysentery, respiratory pathologies, and microbial infections [3,9]. The manufacturing industries use pomegranate aril and peel as a raw material in the production of jams, ink, dye, and oil [3].

#### *Trends in Production and Trade of Pomegranate Fruit in South Africa and Globally*

There has been a rapid increase in the production of pomegranate globally, but the trade has grown more locally in the major producing countries [14,15]. Countries such as India, China, Iran, and Turkey are the leading producers, while India and Iran are the highest exporters of the fruit [2]. However, because the fruit are often grown and picked from small farms in different locations in the major producing countries, there are no articulated data available about global production area [1,2,15]. However, global production was estimated to have increased from about 3 million tonnes in 2014 to 3.8 million tonnes in 2017 [1].

The production of pomegranate fruit in different parts of the world is primarily divided into two (Northern Hemisphere and Southern Hemisphere) due to different seasons of production in the regions [15,16]. The demand for the fruit, especially in the Northern Hemisphere, is derived in nature in the sense that it is mainly driven by industrial usage since there is no close substitute for the antioxidants found in pomegranate [15]. The supply is stratified according to the variation in the production seasons, which allows the Southern Hemisphere to fill the niche market gap in the Northern Hemisphere. The Northern Hemisphere, however, accounts for above 90% of the total production, hence, it has a higher share in the global trade [15]. According to Kahramanoglu [1], global pomegranate production area is increasing, but some of the producing countries are facing quality issues, which leads to considerable postharvest losses and waste. Europe is the biggest market for pomegranate followed by Asia and the Middle East, as almost all the producing countries share the European markets [1]. Peru and Chile are the biggest exporters of pomegranate fruit from the Southern Hemisphere with 74% and 14% respectively, while South Africa and Argentina have a combined 12% contribution to export from the region [17]. Iran, China, India, Turkey, Spain, and Israel are the highest producers in the Northern Hemisphere, but most of the production in this region is consumed locally [1,14].

The pomegranate fruit is one of the deciduous fruits grown in South Africa, occupying about 1024 hectares of land in 2019 from 771 hectares in 2011 [16]. It is mostly grown in the Western Cape, which accounts for about 81% of total production [16]. In South Africa, the majority of the production is exported, which earns export revenue for the country and income for the farmers and value chain actors. In 2019, about 76% of the total production was exported [16], and in 2018, the local market generated about ZAR 67,000 per tonne [17]. Production and export have grown from about 837,250 cartons (3.8 kg equivalent) in 2014 to 1,676,160 cartons (3.8 kg equivalent) in 2019, and are projected to increase to 2,055,271 cartons (3.8 kg equivalent) by 2024 [16]. Between 2014 and 2019, about 7,557,906 cartons (3.8 kg equivalent) were exported [16]. The major market for South African pomegranate is Europe. About 61% of the total export is in the European markets and 22% in the Middle East, with Asian and African countries importing a small amount [17]. The main competition for export market share comes from the Southern Hemisphere countries, whose pomegranate fruit is ready in the market almost in the same period as that of South Africa.

While the pomegranate industry is growing rapidly in South Africa and globally, fruit are susceptible to losses and waste (wastage) which reduce profitability due to a wide range of preharvest and postharvest factors, including pest and disease attack [18,19], bruise damage [20], moisture loss [21,22], and mechanical damage [23]. Industry estimates in South Africa also suggest that the incidence sunburn (a preharvest skin defect) alone can be high, causing grower losses that may exceed 30% of harvested fruit [24]. Despite the identified causes of wastage of the fruit in South Africa, there is a lack of quantitative and science-based data on the magnitude of losses to guide the implementation of loss reduction strategies. During typical packhouse operation, fruit are cleaned, sorted, graded, labelled, and packed, and those that do not meet quality specifications due to the preharvest and postharvest factors outlined are considered as loss and thus discarded or sold at a nominal price for juice or animal feed. As the last point of fruit handling and quality control prior to storage, marketing, and distribution, the packhouse is a critical step in assessing the magnitude and causes of fruit postharvest loss which are critical pieces of information for informing loss reduction strategies. Discussions on the magnitude of postharvest losses and the causes are often based on estimates, without site-level measurements which are known to be difficult and costly. However, researchers globally agree on the need for more studies to directly quantify the amount of postharvest food losses and to identify the site-specific contributing factors along the value chain [25–28]. Therefore, the objective of the current research was to assess the magnitude of pomegranate fruit postharvest losses at the packhouse level based on a case study in South Africa, identify the causes, and estimate the socio-economic and environmental impacts of the losses.

#### **2. Materials and Methods**

#### *2.1. Study Settings*

The study was conducted from February to March 2020 in the Western Cape Province (Latitude 33.2278◦ S, Longitude 21.8569◦ E) of South Africa. The province was chosen because over 80% of total production of pomegranate fruit in the country is done in the region [16] and the case study packhouse is arguably the biggest packhouse in the area. The study was conducted on the three most commercially grown pomegranate cultivars in the country, namely 'Herskawitz', 'Acco', and 'Wonderful'. 'Herskawitz' has a sour taste with hard seeds, 'Acco' has a sweet taste with softer seeds, while 'Wonderful' has a vinous taste with soft seeds [29]. The study was carried out by assessing the physical quality of fruit sorted as 'waste' from the packhouse production line. The assessment started at about 9:00 a.m. and ended by 3:00 p.m. daily. 'Herskawitz', which is the early cultivar, was assessed by mid-February while 'Acco' was assessed by early March. 'Wonderful' was assessed by mid and late March. The handling and packaging practices at the packhouse were observed. The unit of measurement of lost fruit was the bin [length (1270 mm) × width (1070 mm) × height (720 mm)]. A total of 251 bins, containing 1300–1500 fruit each which were processed by the packhouse during the study period, were used to assess the magnitude of fruit losses ('Herskawitz' 84, 'Acco' 89, and 'Wonderful' 78) by putting fruit through the packhouse line for sorting and grading. The bins handled by the packhouse during the study period were all examined in order to provide a sufficient and representative dataset based on commercial practice. The magnitude of loss was estimated for each pomegranate cultivar based on the number of waste bins containing lost/rejected fruit. Fruit sorted into waste bins were sampled into ventilated cartons (length (35 mm) × height (25 mm) × width (22 mm)) and later examined individually to determine the causes of loss. A total of 18 bins containing lost (discarded) fruit, six bins for each cultivar, were used to determine the causes of fruit loss by examining each fruit individually. Given that the same person carried out all the individual fruit assessment to reduce human error, this was the maximum number of bins and fruit that could possibly be examined during the research period. Loss calculations included the number of bins of discarded fruit for defect reasons proportional to the number of bins put in the processing line. The assessment was made based on the external quality of fruit. Quantification was done by collecting sample fruit to identify reasons for loss (defects) and how they contribute to total fruit loss.

#### *2.2. Method of Data Collection*

The research method for this study was the sampling method, which has been identified as a practical method for conducting a study where there is a large variable of data to consider and also in conditions where data collection is constrained [30]. Because the assessment of this present study was carried out simultaneously during full packhouse commercial operations, which constrained space and time for data collection, it was necessary to use the sampling method. Researchers have used sampling methods to conduct

postharvest studies [31–33]. This present study involved the physical identification of the causes of fruit loss by examining individual fruit sorted into the waste bin at the packhouse. Qualitative data were also collected by physical observation during packhouse operation and interaction with the packhouse workers.

The economic impact of fruit losses was estimated using the supermarket retail price (ZAR 89.99/kg) in Stellenbosch, Western Cape, South Africa during the period of study. The environmental impacts were estimated using the values from previous studies reported in literature. The energy used for storage and processing activities and greenhouse gas (GHG) emission associated with fruit production were estimated using 6.1 MJ/kg and 0.48 CO2 eq/kg, respectively [34]. The values were estimated for apples, which is a deciduous fruit like the pomegranate and which have similar packhouse processes. The water footprint was estimated with 910 m<sup>3</sup> ton−<sup>1</sup> [35]. The nutritional impacts were calculated using values from [36] and [37]. Furthermore, cropland use was estimated by the size of the farm and the average yield produced.

#### *2.3. Data Collection*

The data collection protocol was consistent with the direct measurement method of the Food Loss and Waste Protocol (FLWP) [38]. For fruit loss data collection, a total of 251 bins (containing 1300–1500 fruit each) were put through the packhouse line and the number of waste bins (fruit loss) produced for each cultivar were recorded. Altogether, a total of over 351,400 individual fruit were assessed which comprised of 89, 84, and 78 bins of 'Acco', 'Herskawitz', and 'Wonderful' pomegranate, respectively. To determine the causes for the loss, fruit in 18 waste bins (6 per cultivar) were further examined. For each bin, a sample of 30 fruit was randomly selected each from the bottom, middle, and top and placed into ventilated cartons. Each fruit was visually assessed based on physical appearance (presence of rot, *Alternaria* disease, crack, injury, sunburn, blemish, insect damage), sorted, counted, and recorded according to each type of defect. In total, 1630 fruit (540 per cultivar) were examined to determine the quality defects causing fruit loss.

Data collection for each cultivar was done in three days, and six bins (n = 6) were assessed per cultivar ('Acco', 'Hershkawitz', and 'Wonderful'). The waste bins were labelled and two bins were assessed per day. It is important, however, to mention that pomegranate fruit losses at the packhouse level are not necessarily cultivar dependent, rather they originate from direct (primary sources) and indirect (secondary sources) [39]. Nonetheless, it was important to categorise fruit defects by cultivar for ease of data collection and comparison with historical packhouse data.

#### *2.4. Historical Packhouse Data*

Historical data on pomegranate postharvest fruit losses collected by quality control staff at the case study packhouse for the two years where data were available (2016 and 2019) were obtained as secondary data. These data are presented and discussed in comparison with the results obtained in the present study.

#### *2.5. Statistical Analysis*

Microsoft Excel 2013 (Microsoft Corporation) was used to collate the data collected. In order to find the trend of variation between cultivars and fruit defects and to consider their correlation, data were investigated according to principal component analysis (PCA) using XLSTAT software Version 2012.4.01 (Addinsoft, Paris). The mean value ± standard error of fruit defects was also presented and where there was a statistical significance difference (*p* < 0.05), analysis of variance (ANOVA) was performed using Statistica Version 13.5.0 to evaluate the differences between cultivars and fruit defects. Significant differences between means were separated using Duncan's multiple range test.

#### **3. Results**

#### *3.1. Magnitude of Fruit Losses and Waste*

The magnitude of pomegranate fruit losses at the packhouse was measured by the proportion of bins of discarded fruit to the number of bins initially put in the fruit processing line. Loss quantification involved a total of 251 bins of fruit put into the processing line from the three cultivars studied, of which 18 bins were discarded for failing to meet the minimum market required standard. The total lost fruit among the three cultivars ranged from 6.74 to 7.69% (Table 1). 'Acco' produced the least lost fruit as 89 fruit bins put in the processing line produced 6 bins of discarded fruit, while 84 fruit bins of 'Hershkawitz' produced 6 bins of discarded fruit. Lastly, 'Wonderful' produced the highest amount of lost fruit as 78 bins of fruit put in the processing line produced 6 bins of discarded fruit.

**Table 1.** Amount and percentages of each pomegranate cultivar fruit lost (discarded) based on the amount of fruit put through the packhouse line.


Estimates of pomegranate fruit losses at the packhouse level in South Africa have been reported in recent years by the Pomegranate Association of South Africa (POMASA). In 2017, POMASA reported 11% loss in 'Wonderful', 13% loss in 'Hershkawitz', and 11% loss in 'Acco' [40]. In 2018, a 7% loss of 'Wonderful' was reported, an 8% loss in 'Hershkawitz', and a 9% loss in 'Acco' [18]. Additionally, in 2019, 9% of 'Wonderful' was reported as a loss, 25% loss in 'Hershkawitz', and 13% loss in 'Acco' [16]. Pomegranate fruit loss estimation at the packhouse is measured throughout the production season with fruit from multiple farmers with different preharvest and postharvest practices, which could affect the quality of fruit delivered to the packhouse and, hence, the amount of loss recorded. These factors account for the higher incidence of postharvest losses at the packhouse based on reported historical industry-wide data compared with the site-specific results obtained in the current study through a case study.

Bond [41] reported a 20% loss in carrots at the packinghouse level in Norway. The estimation was done using secondary data from experts in the carrot industry and surveys with semi-structured interviews with managers of packhouses. The study revealed that mechanical damage (harvesting technique at the farm) is a major source of loss at the packhouse since the superficial injuries during harvest open wounds for decay and disease infestation. A postharvest loss assessment of avocado, banana, guava, mango, papaya, and tomato was carried out among fruit growers and traders in north-western Ethiopia by Bantayehu et al. [42]. The results show that 18–28% of losses occurred during harvesting, storage, and transportation, while 18–25% of losses were reported at transportation and marketing levels. The major causes of loss are superficial injury, bruising, sunburn, handling technique, and physiological disorders, which are similar to the causes of pomegranate fruit loss in this present study. Semi-structured questionnaires and interviews were used for data collection in the study. Furthermore, a study in Nepal reported 35% loss in carrots [43]. Farmgate loss was estimated at 10%, 2% at a collection point, 5% at the wholesale market, and 18% at the retail level, and crack and splits were identified as the major cause of carrot loss [43]. Irrespective of the magnitude of loss reported in the studies, losses due to environmental stress and mechanical damage have remained dominant among the causes of fruit loss, which are similar to the results of this present study.

#### *3.2. Causes of Packhouse Pomegranate Fruit Losses*

The causes of packhouse pomegranate fruit losses were assessed based on the quality issues of why fruit were removed from the packhouse processing line as waste. These quality issues have contributory factors, and some are direct (primary source) while some are indirect (secondary source) [39]. The main indirect (secondary) cause of packhouse pomegranate fruit loss is the high market standard. South Africa exports about 76% of the total pomegranate production [16] and 61% of the total export goes to the European markets [17]. The trend of pomegranate marketing in Europe shows that South Africa faces strong competition with other countries of the Southern Hemisphere for the market share [1,16]. This competition is believed to have raised the market standard, which means that only premium quality fruit are processed for export at the packhouse. The implication of this is that pomegranate fruit are sorted again at the packhouse to ensure that only the best quality fruit are packed for sale. The 'good fruit' that are deemed not to meet the premium quality required in the export market are sold locally. The effect of this is that more fruit are lost or sold at a cheap price for juicing and other purposes. Additionally, handling at the packhouse is another source of loss categorised as a direct (primary) source of loss. Losses due to handling manifested mainly as fruit bruises and superficial injuries. However, the two major reasons for physical loss as identified in this study were sunburn and injury. Other reasons are *Alternaria*, bruises, cracks, being oversized, insect damage, rot, decay, blemishes, and malformation.

3.2.1. Environmental Stress (Sunburn, Cracks, and Splits) Sunburn

In the three cultivars assessed, sunburn was recorded as the highest cause of loss. Losses due to sunburn at the packhouse originated from the farm where pomegranate fruit were exposed to direct sunlight, which causes discolouration of the rind of the affected fruit, hence downgrading the fruit quality [44]. This shows the effect of high temperature on the quality of pomegranate fruit. After sorting for premium quality fruit at the packhouse, sunburn accounted for 28.70% and 29.8% of the discarded fruit in 'Acco' and 'Hershkawitz', respectively (Table 2). The highest fruit loss incidence was in 'Wonderful', where it contributed to 34.81% of losses. Sunburn showed a positive relationship with oversized fruit in the correlation analysis result (Table 3). This relationship is the only positive relationship result in the analysis, which indicates that more oversized fruit with sunburn were deemed fit for export at the farm level but could not meet the minimum market standard according to the evaluation of the packhouse. The market standard in Europe and the Middle East does not allow fruit with noticeable sunburn, which means that such fruit are sold at a low price locally, mainly for juicing.


**Table 2.** Percentage fruit loss of three pomegranate cultivars due to different defects at packhouse.


**Table 3.** Pearson correlation coefficient matrix between defects on three pomegranate cultivars ('Acco', 'Hershkawitz', and 'Wonderful').

Values in bold are significant at *p* < 0.05.

Temperatures exceeding 35 ◦C and low relative humidity at the farm level contribute to a higher incidence of sunburn [45] and because 'Wonderful' pomegranate produces bigger fruit with a larger surface area and is a late cultivar in South Africa, this results in fruit hanging on the tree much longer before harvest. With most of the fruit exposed to direct sunlight outside the tree canopy, the incidence of sunburn is exacerbated. This combination of factors makes 'Wonderful' pomegranate fruit more susceptible to sunburn than 'Acco' and 'Hershkawitz'.

#### Cracks and Splits

The results show that the amount of fruit affected by cracks and splits in the three cultivars studied are similar as they ranked third in the causes of loss in the cultivars. The highest incidence was in 'Acco', where they accounted for 18.70% of losses (Table 2). For 'Hershkawitz', cracks and splits contributed to 18.34%, while in 'Wonderful', they accounted for 17.96% of losses. Cracks and splits had a negative relationship with sunburn according to the correlation analysis result (Table 3). This shows the impact of fruit sorting at the farm level; otherwise, it is reasonable to believe that higher sunburn would result in more cracks and splits due to the hardening of fruit rinds due to direct sunlight, which aids cracking when the moisture content fluctuates. Like sunburn, pomegranate cracks and splits as observed at the packhouse mostly originated from the farm and were a result of environmental stress, specifically soil moisture imbalances [46,47] as pomegranate fruit are highly sensitive to variation in the soil moisture content [48]. Therefore, fruit with cracks and splits at the packhouse are due to either oversight by the farm fruit sorters or the assumption that the fruit could meet the minimum market standard.

Cracks and splits create an open wound that enhances moisture loss and disease infestation, which lowers the quality of the affected fruit [49]. Fruit discarded from the packhouse due to cracks and splits were sold locally for industrial use.

3.2.2. Mechanical and Physical Damage (Superficial Injuries, Bruise Damage, and Blemishes)

#### Superficial Injuries

Superficial injuries were the second highest cause of pomegranate fruit loss at the packhouse after sunburn. Injuries constituted 23.33% of the total loss in 'Acco' (Table 2). For 'Hershkawitz', injury contributed 23.70% of the loss, which is the highest incidence of injury recorded among the three studied cultivars. 'Wonderful' recorded the least amount of injury with 19.07% of losses in the cultivar. Superficial injuries showed a negative relationship with oversized fruit in the correlation matrix (Table 3). This indicates that a higher incidence of injury was due to handling and not fruit sizes. Some of the superficial injuries observed were cases of opening fruit with a suspicion of internal disease by packhouse fruit sorters with false results. Furthermore, losses due to injuries originating from preharvest and handling technique at the farm level were observed. Injuries in this category were deemed insignificant at the farm level, but the affected fruit failed to meet market standards by the packhouse. Pomegranate fruit were only stored for a few days (when necessary) at the packhouse before they were processed; therefore, chilling injuries were not observed.

#### Bruise Damage

The results show that bruise damage is the fourth cause of loss in the three pomegranate cultivars assessed. 'Acco' recorded the highest incidence of bruise damage, which accounted for 13.33% of losses in the cultivar (Table 2). Bruise damage contributed to 12.80% of the losses recorded for 'Hershkawitz' and 10.94% of the losses in 'Wonderful'. Bruise damage showed no significant relationship with any other defect in the correlation analysis result (Table 3), which suggests that bruise damage at the packhouse is solely a function of mechanical damage during transportation and handling at the packhouse.

Like an injury, a bruise is caused by mechanical damage as a result of impact during harvesting, transportation, and handling [50]. Most of the bruises observed were believed to occur during transportation to the packhouse and packhouse handling. Many farm roads are rough, thereby causing vibration and compression of the fruit during transportation, which results in bruising damage [50,51]. Moreover, vibration and impact occur during fruit unloading at the packhouse and conveyance to the processing line. These assumptions were made because the affected areas of the fruit were already brownish in colour and soft, illustrating that the bruising was not an immediate occurrence. However, there were cases where the affected fruit were discarded during packaging with no visible discolouration of the rind but with softness in the affected parts. Bruised fruit do not meet either the export or the local market standards, and therefore, are sold at a low price for industrial use.

#### Blemish

Blemish is one of the least frequent causes of loss in the three pomegranate cultivars studied. For 'Acco', it ranked seventh out of eight in the causes of loss and accounted for 3.30% of losses. It ranked fifth in 'Hershkawitz' and contributed to 3.30% of fruit loss. The highest occurrence of blemish was recorded in 'Wonderful' with 3.70% of losses. The presence of fruit with blemish at the packhouse is usually the result of oversight from the on-farm fruit sorters as they are unlikely to be caused by packhouse handling operations. Blemish is mostly a result of mechanical damage during and after pruning before pomegranate fruit are picked. Again, sharp tree branches scratch fruit when thrown against them by the wind, leaving blemish marks on the affected fruit. Blemish is a strong factor in determining pomegranate fruit quality both for export and local market because external attractiveness of pomegranate fruit depends strongly on a blemish-free appearance [52].

#### 3.2.3. Biological Damage (Insect Damage) Insect Damage

The results show that insect damage contribution to pomegranate fruit losses at the packhouse was low. The highest incidence of insect damage was in 'Acco', where it ranked sixth in the causes of loss and accounted for 3.90% of losses (Table 2). The lowest incidence was in 'Hershkawitz' with 2.20% of losses and ranked eighth in the causes of loss. For 'Wonderful', it accounted for 2.77% of losses. Insect damage had no significant relationship with other defects assessed in the correlation analysis (Table 3). This indicates that insect damage in this present study occurred independently of other defects and that it was not as a result of packhouse operation. It could also mean that a significant amount of fruit damaged by insects were discarded at the farm level.

Insect damages downgrade the quality of pomegranate fruit since a small portion of the fruit is consumed, which results in a partial loss of the affected fruit and in making them not meet market standard. The affected fruit were discarded from the processing line and sold at a low price since part of the fruit could still be used for other purposes such as the manufacturing of dye and animal feed.

#### 3.2.4. Microbial and Pathological Spoilage (Decay and Rots, *Alternaria*, Crown Rot) Decay and Rots

Decay and rots are one of the least frequent causes of pomegranate fruit loss among the three cultivars assessed at the packhouse. For 'Acco', it accounted for 2.22% of losses (Table 2). They contributed to 1.90% of losses in 'Hershkawitz' and 2.22% in 'Wonderful'. Decay and rot had no significant relationship with other defects in the correlation analysis (Table 3). This indicates that decay at the packhouse, in this present study, was not a result of packhouse operation (handling). Therefore, the decayed fruit were because of a sorting oversight at the farm level. Decay and rot are a result of microbial pathogens that break down the rind of the affected fruit, which results in partial or total decay and rot [20]. Decayed fruit do not meet market standard and are often buried or composted.

#### *Alternaria*

*Alternaria* disease varied among the three studied cultivars at the packhouse. However, its contribution to total fruit loss was low. The highest incidence of *Alternaria* was in 'Acco', where it contributed to 4.30% of losses (Table 2). For 'Hershkawitz', *Alternaria* accounted for 3.10% of loss and ranked sixth in the causes of loss in the cultivar, and contributed 2.96% of loss in 'Wonderful'. *Alternaria* disease occurs at the farm and fruit discarded at the packhouse due to the disease were due to a sorting oversight at the farm because often, it is difficult to determine infected fruit physically.

*Alternaria* is a pomegranate fruit disease caused by the *Alternaria alternata* pathogen. The disease causes fruit to decay partially or totally from the inside. In contrast, the rind of the affected fruit appears healthy [19]. The affected fruit are light in weight, which makes them float during chlorine baths at the packhouse processing line. *Alternaria*-affected pomegranate fruit are intensely reddish in colour compared to an *Alternaria*-free fruit. These fruits are often buried or composted.

#### Crown Rot

Crown rot accounted for a low amount of pomegranate fruit loss at the packhouse. It contributed to 2.22% of losses in 'Acco' (Table 2). The highest occurrence of crown rot was in 'Hershkawitz', where it accounted for 2.96% of loss and ranked seventh in the causes of loss for the cultivar. For 'Wonderful', it ranked tenth in the causes of loss and accounted for 1.67% of losses. Crown rot showed no significant relationship with other defects in the correlation analysis (Table 3), which suggests that it occurred for reasons outside of the packhouse. Like *Alternaria*, crown rot is a farm disease and did not originate at the packhouse, rather, it was found due to a sorting oversight at the farm.

Crown rot is caused by *Coniella granati*, a fungi pathogen [19], which mostly affects pomegranate fruit on the farm. The rind of the affected fruit shows the presence of pycnidia with rotten crown [19]. Fruit affected by crown rot were discarded for not meeting the market standard, and as such, were sold at a cheap price for industrial products such as ink and dye.

#### 3.2.5. Irregular Fruit Size and Shape (Oversized and Misshapen)

#### Oversized

Oversized fruit were only observed among the 'Wonderful' cultivar and in a very small quantity. Therefore, oversized fruit contributed little to overall pomegranate fruit loss in the cultivar. Oversized fruit accounted for 2.24% of loss (Table 2). The oversized fruit were not able to fit comfortably into the 3.8 kg equivalent carton used for pomegranate fruit packaging, and therefore, were sorted to be sold and used for other purposes such as juicing.

#### Misshapen

Pomegranate fruit discarded for being misshapen were very few and contributed least to the causes of loss. Such fruit were found only in 'Hershkawitz' and 'Wonderful'. For 'Hershkawitz', it contributed to 1.90% of loss, and in 'Wonderful', 1.66% (Table 2). The misshapen fruit were good fruit with irregular shapes, hence, they did not appear appealing for the shelves but could be used for producing juice, jam, and dye.

#### *3.3. Comparative Analysis of Pomegranate Fruit Based on Defects*

Fruit were discarded from the processing line for not meeting market standard due to bruising and injury (during handling), and other defects such as sunburn and microbial and pathological diseases that originated from the farm. Although packhouse defects are not considered cultivar-dependent, this study evaluated the relationship between pomegranate fruit defects and the cultivars using principal component analysis (PCA). The result was observed in biplot axes, which shows a relationship by the clustering of active variables (defects), in the red colour, around active observations (cultivars), in the blue colour (Figure 1). The result revealed that oversized and misshapen fruit were most common amongst the 'Wonderful', as evidenced by their clustering around 'Wonderful'. At the same time, insect damage and *Alternaria* were predominant in 'Acco'. Decay and crown rot were primarily associated with 'Herskawitz'. Bruise and injury, which are mainly due to fruit handling, were observed to affect the three cultivars relatively equally. Environmental stress factors (sunburn and cracks) were also found to affect the three cultivars in a similar proportion. A dendrogram cluster analysis was done to evaluate whether different packhouse management practices would be advisable for the handling of each cultivar (Figure 2). The result suggests that implementing different packhouse management practices is not necessary for each cultivar as the three cultivars clustered around each other in cluster 2 and 3, which supports the fact that packhouse fruit loss is not cultivar dependent, rather due to postharvest handling practices and preharvest factors which caused some of the defects ab initio. Cluster 1 consists only of 'Wonderful', and this could be attributed to misshapen and oversized fruit, which were majorly associated with the cultivar.

**Figure 1.** Observation chart showing fruit defects according to cultivars.

**Figure 2.** Dendrogram of cluster analysis of three pomegranate cultivars studied based on defects. Key: wond = 'Wonderful', acco = 'Acco', hersk = 'Hershkawitz'.

The analysis of variance (ANOVA) was performed to evaluate differences in how the defects affect cultivars, as presented in Table 4. The effects of defects on 'Acco' and 'Hershkawitz' were similar but different in 'Wonderful' except for sunburn and superficial injury. The defects originated from sources such as environmental stress, mechanical and physical damage, biological damage, microbial and pathological spoilage, and lastly, irregular fruit size and shape (Table 4). The results show that environmental stress was the major cause of pomegranate fruit losses at the packhouse. However, it is important to note that the environmental factors originated from the farms and the affected fruit were discarded at the packhouse as they did not meet the required market standard. Environmental stress accounted for the highest incidence of loss, with 49.44% of the total losses. Mechanical and physical damage also caused significant loss of fruit, accounting for 37.84% of total fruit losses. The biological damage factor was only insect damage, which contributed 2.96% of losses while irregular fruit size and shape contributed least to losses with 1.92% and were mostly in 'Wonderful'. Lastly, microbial and pathological spoilage accounted for 7.84% of total losses.


**Table 4.** Comparison between cultivars and fruit defects contributing to postharvest loss in the case study packhouse.

\* Mean values in the same row followed by different letters (a–f) indicate significant differences (*p* < 0.05).

#### **4. Discussion**

*4.1. Historical Packhouse Data on Pomegranate Fruit Losses at Case Study Packhouse in Wellington, Western Cape, South Africa*

Historical fruit loss data for 2016 and 2019 at the case study packhouse were analysed in comparison with the results of this present study and presented in Figure 3. The result suggests that marketing standard is a major source of fruit loss at the packhouse. This means that some fruit deemed suitable for marketing (export and local) at the farm level do not meet the packhouse marketing standard as a result of defects originating from the farm. This is evident in the contribution of sunburn and cracks to fruit losses as compared to bruise and injury, which are believed to be because of transportation and handling at the packhouse level. Furthermore, blemish, which also originates from the farm, was found to account for a significant amount of fruit loss at the packhouse according to both the packhouse historical data and the result obtained from the present study.

**Figure 3.** Comparison of historical packhouse pomegranate fruit defect data (2016 and 2019) and the present study.

#### *4.2. Economic, Environmental, and Resource Impacts*

The impacts of pomegranate fruit loss estimated in this study are based on the magnitude of incidence of pomegranate fruit loss at the case study packhouse in Wellington, Western Cape Province and retail price in South Africa. This is to reveal the potential production inputs and resources that are wasted in producing the pomegranate fruit that are lost. For example, the energy used for the production of wasted food could be used for another productive purpose such as cold storage to preserve food. Typically, the amount of packhouse fruit loss at the national and global level might be different depending on a range of factors including production practices, postharvest handling, and the market standard at the importing markets. The estimations are particularly important to raise awareness on the importance of reducing fruit losses at the packhouse level given several sustainability challenges that the world is facing, which require prudent use of resources today to create a future with sufficient material and natural resources [53].

The retail price of pomegranate fruit at the supermarket means that ZAR 88.99 (USD 5.26) is lost per 1 kg of lost pomegranate fruit in South Africa. Based on the annual average loss of 7.16% at the case study packhouse (Table 5), which translates to 328.79 tonnes, the monetary loss of the total annual production was estimated at ZAR 29.5 million (USD 1,754,984). During the production of pomegranate fruit, greenhouse gases(GHGs) are emitted into the atmosphere. Based on the findings of this study, the pomegranate losses at the packhouse level were estimated to emit about 157,819 CO2 eq. To sink this amount of CO2 eq would require planting about 4 million trees at 0.039 metric ton CO2 per tree planted [54]. Furthermore, an estimated 2,005,619 MJ of energy and 299,198.9 m3 of water were wasted in production. This amount of wasted water could meet the daily water requirement of up to 109,896 persons in a year at 0.05 m3 utilised per person per day [55]. Again, the production of the lost fruit could take up to 8.54 ha of land, that could have otherwise been used to provide public utilities such as a shopping complex.


**Table 5.** Summary of the magnitude of pomegranate fruit losses and impacts at the packhouse, South Africa, and global levels.

\* Production statistics is estimated from Sonlia packhouse [56]. <sup>a</sup> Supermarket retail price in Stellenbosch, Western Cape, South Africa.

b,c Impacts per unit fruit produced estimated from [34]. <sup>d</sup> Impact per unit fruit produced estimated from [35].

The economic and environmental impacts of pomegranate fruit losses at packhouse were also estimated at the national (South Africa) level. Losses at the national level were estimated at 2332.16 tonnes (Table 5), which translates to an estimated ZAR 209.87 million (USD 12.64 million) annual revenue loss. Losses at the national level were found to emit about 1.11 million CO2 eq. To sink this amount of CO2 eq would require planting at least 28 million trees at 0.039 metric ton CO2 per tree planted [54]. Furthermore, about 14.22 million MJ of energy and 2.12 million m3 of water were wasted to grow the lost fruit. The wasted water could meet the daily water requirement of about 116,289 people for a year at 0.05 m<sup>3</sup> consumed per person per day [55]. Lastly, the land used to produce the lost fruit was estimated at 60.58 ha of land.

Furthermore, the economic and environmental impacts of pomegranate fruit losses were estimated at the global level using the incidence of losses and retail price in South Africa. This assumes a 7.16% loss of total fruit conveyed to the packhouse for processing globally, which was estimated at 224,792 tonnes (Table 5) and a retail price of ZAR 88.99/kg (USD 5.26/kg). The revenue loss due to the lost fruit was estimated at ZAR 20.22 billion (USD 1.2 billion). Based on the estimation, about 107.90 million CO2 eq were emitted annually due to losses of pomegranate fruit. To sink this amount of CO2 eq would require planting at least 2.7 billion trees at 0.039 metric ton CO2 per tree planted [54]. Additionally, about 1.37 billion MJ of energy and 204.56 million m<sup>3</sup> of freshwater were wasted. The wasted water could meet the daily water requirement of about 11.2 million people for a year at 0.05 m<sup>3</sup> utilised per person per day [55]. Lastly, about 5838.77 ha of land was used to produce the lost fruit. Postharvest losses of pomegranate fruit mean a significant loss of revenue and resources that could have otherwise been put to beneficial use.

#### *4.3. Nutritional Impacts*

The loss of pomegranate fruit contributes to food and nutritional insecurity in South Africa due to a huge loss of essential nutrients in the lost pomegranate fruit. Some of the nutrients lost due to postharvest losses at the case study packhouse in Wellington, Western Cape Province of South Africa during the 2020 season are presented in Table 6. The nutritional impacts of fruit and vegetable cannot be over-emphasised, especially given the effect of the COVID-19 pandemic on the livelihood of individuals and their ability to afford healthy and nutritious food. Based on the annual loss of pomegranate fruit during operations at the case study packhouse, the lost content of sodium, fibre, carbohydrate, iron, and ascorbic acid in fruit were estimated to meet the daily recommended nutrition intake of 1, 7, 25, 5, and 66 people, respectively.


**Table 6.** Selected nutritional impacts of pomegranate fruit losses at the case study packhouse, Wellington, in the Western Cape Province of South Africa.

\* Amount lost is based on [32]. \*\* Nutritional loss is based on [31]. ## Amount lost is estimated in g100−<sup>1</sup> g.

The nutritional impacts of pomegranate fruit losses were also estimated at the national (South Africa) level using the incidence of losses at the case study packhouse, in the Western Cape Province of South Africa (Table 6). Based on the annual losses of pomegranate fruit at the packhouse level, the estimate at the national level suggests that the lost content of sodium, fibre, calcium, magnesium, and ascorbic acid in fruit could meet the daily recommended intake of 5, 47, 70, 90, and 466 people, respectively.

The estimation of postharvest nutritional losses of pomegranate fruit at the global level showed a huge loss of essential nutrients that could benefit people in a period where micro and macronutrient deficiency affects not less than a third of the world population and negatively impacts the quality of life [57]. Based on the annual incidence of losses in South Africa, the selected nutrient loss globally due to pomegranate losses at the packhouse was estimated (Table 6). The lost content of sodium, fibre, protein, potassium and ascorbic acid in fruit could meet the daily recommended nutrition intake of 450, 4496, 6842, 8179 and 44,959 people respectively. The findings revealed that postharvest losses of pomegranate fruit at the packhouse level also contribute to global food and nutrition insecurity.

#### *4.4. Possible Solutions to Overcome and Limit Fruit Loss at the Packhouse*

This study identified quality issues that lead to the downgrading of a significant proportion of the fruit processed at the packhouse. The quality issues are categorised into indirect (secondary) and direct (primary) causes of loss [39]. Indirect sources of loss are mainly due to high market quality standard at the importing markets. At the case study packhouse, pomegranate fruit that did not meet market quality standard were majorly due to the loss of aesthetic and physical appeal because of defects and damages leading to downgrading. Fruit losses due to high market quality standards could be classified as unavoidable loss [58]. This is because market quality standards are determined by market specifications on produce quality attributes and economic factors that are beyond the control of the packhouse operation. Under this situation, the application of the best available postharvest technologies at the packhouse cannot prevent such losses due to products that fall short of market standards.

Fruit losses due to direct (primary) causes at the case study packhouse include losses due to postharvest handling of fruit during transportation from storage to the processing line, sorting and grading; these are manifested as superficial injuries, cuts, and bruises [50]. Since poor postharvest handling practices are a major cause of fruit loss, possible solutions to reduce loss must be practical and technologically driven [59,60]. Fruit quality improvement can be achieved by local investment in technological innovations through research to improve knowledge in life cycle assessment, processing, and handling of pomegranate fruit at the packhouse [59,61,62]. The conventional manual sorting technique used at the packhouse is subjective and often leads to damaging wholesome fruit because fruit sorters most times are unable to make distinction between internally damaged fruit and a good fruit. Hence, possible technological improvements in the packhouse line such as non-destructive sorting techniques using remote sensing along the processing line would

limit basic sorting errors leading to cutting fruit open to ascertain the presence of internal diseases. In addition to technological innovation, the reduction of fruit loss will require the continuous training of packhouse staff on fruit handling, especially the fruit sorters and forklift drivers. This is important because reckless transportation from temporal cold storage to the packhouse processing line causes bruises, which lead to fruit loss. This could be limited by educating forklift drivers about the impact of vibration and compression on pomegranate fruit.

#### **5. Conclusions**

This study found that pomegranate fruit loss at the case study packhouse in Wellington, Western Cape Province of South Africa ranged between 6.74 to 7.69%. This translates to 328.79 tonnes of pomegranate fruit removed from the packhouse processing line per production season. This amount of fruit is removed from the value chain for not meeting the minimum market standard and are sold at a low price for juicing and as raw material for dye and ink production. The major direct cause of pomegranate fruit loss at the packhouse, as identified in this study is handling (bruise and injuries). Environmental stress (sunburn and cracks) and microbial and pathological diseases were also contributors to loss. It is interesting to note that the result of the causes of loss in this study is similar to the historical packhouse report as analysed.

The result of the magnitude of losses shows that the incidence of loss was lowest in 'Acco' with 6.74% of losses. The amount of loss in 'Herskawitz' and 'Wonderful' were similar with 7.14% and 7.69%, respectively. Market standard (especially the export market) is greatly influential on the amount of losses recorded at the packhouse. This is because most of the produce are exported to Europe and the Middle East, where only premium quality fruit are accepted. This means that fruit deemed marketable at the farm level may be discarded at the packhouse resulting in loss.

Packhouse fruit losses have a huge economic, environmental, resource, and nutritional impacts as exemplified in this study. The economic impact reflects the loss of revenue by farmers and other actors along the value chain. Environmental and resource impacts are evident in the unsustainable use of resources to produce lost and wasted fruit, and the nutritional impact results in food insecurity due to the wasted nutrients that would have otherwise benefitted people. Considering the various impacts of postharvest losses at the packhouse level, postharvest losses and waste reduction is a sustainable means of ensuring food and nutritional security. Furthermore, reducing postharvest losses and waste would help mitigate the effects of global warming and increase revenue for the food value chain actors.

**Author Contributions:** Conceptualisation, U.L.O.; methodology, I.K.O.; software, O.A.F.; validation, U.L.O. and O.A.F.; formal analysis, O.A.F.; investigation, I.K.O.; resources, U.L.O.; data curation, I.K.O.; writing—original draft preparation, I.K.O.; writing—review and editing, O.A.F.; visualisation, I.K.O.; supervision, U.L.O., O.A.F.; project administration, U.L.O.; funding acquisition, U.L.O. All authors have read and agreed to the published version of the manuscript.

**Funding:** This work is based on the research supported by the National Research Foundation of South Africa (Grant Numbers: 64813). The opinions, findings, and conclusions or recommendations expressed are those of the author(s) alone, and the NRF accepts no liability whatsoever in this regard. The APC was funded by the NRF (Grant number 64813).

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** The data are not publicly available to protect the privacy of the case study packhouse.

**Conflicts of Interest:** The authors declare no conflict of interest.

#### **References**

