**2. Literature Review**

The world's population is predicted to reach 9.8 billion by 2050 and this will require an increase of 70% in food availability [6]. FL may occur due to technical limitations, such as a lack of proper storage facilities, infrastructure, packaging etc. [8]. FW is generated after the food is spoiled or expires due to poor stock managemen<sup>t</sup> or neglect. FL takes place during the production, post-harvest, and processing stages, while food waste typically occurs at the retail and consumer levels. FL and FW can be evaluated and measured in di fferent ways. There are several definitions of FL and FW taking into consideration pre-harvest and/or post-harvest stages, the use and destination of food, the edible part of food products, or the nutritional value of FL and FW [9]. The inclusion of pre-harvest stages to quantify food loss is essential because the pre-harvest managemen<sup>t</sup> stage can increase the quantity and quality of tomatoes along the value chain [10]. FL and FW have negative food-security, economic, and environmental impacts. FL and FW represent the natural resources (water, land, energy) used to produce food. Reducing loss and waste throughout the food supply chain is an e ffective solution to mitigate the GHG emissions of agriculture and improve global food and nutrition security [8].

In 2011, the FAO estimated that annually around one-third of food produced is lost or wasted globally, which amounts to about 1.3 billion tons per year [11]. The 2030 Agenda for Sustainable Development (target 12.3) calls for halving per capita global FW at retail and consumer levels. FW represents a waste of resources (land, water, energy, soil, seeds, pesticides, etc.) used in its production; furthermore, it contributes to increasing GHG emissions. FL originates from decisions and actions by food suppliers in the value chain, excluding retailers, food service providers and consumers, while FW occurs from decisions by retailers, food service providers and consumers [12].

The global population will grow from its current 7.8 billion in 2020 to 9.8 billion in 2050 and global food demand is estimated to increase by at least 50%, but demand for protein rich products may grow even faster [6]. Closing the food gap requires a decreasing rate of growth in demand by cutting FL and FW, reducing GHG emissions from agriculture, shifting the meat-based diets of high meat consumers towards a plant-based diet, innovation and a voluntary reduction of the birth rate in Africa [13]. According to BCG the annual FL and FW has reached 1.6 billion tons, worth ca. \$1.2 trillion USD, and by 2030 these figures may go up to 2.1 billion tons, worth about \$1.5 trillion USD [14]. Food lost or wasted annually accounts for one-third of global food production and 8% of global greenhouse gas emissions, while over 800 million people worldwide su ffer from malnutrition. FL or FW along the food chain is most striking at the beginning and the end, namely in the production and transportation stage in developing regions, while it is more typical in the retail and consumption stage in developed countries. All stakeholders across the value chain can play a crucial role in food loss and waste reduction [15].

In North America (the US, Canada, and Mexico), annual FL and FW amount to 168 million tons. There are several opportunities to address FL and FW in North America including multi-stakeholder collaboration, standardized data labels, improved cold chain management, and processing and packaging innovation [16–18]. During processing, waste is generated by inadequate infrastructure and machinery, contamination, trimming and cutting problems, confusing date labels, food safety issues and cold chain problems [16–18]. About 40% of the annual US food supply is lost and wasted, so action is required across the food supply chain, with collaboration among agencies, businesses, and communities. The United States Government Accountability O ffice identified three key areas – limited data and lack of awareness about food loss and waste, and limited infrastructure – which should be addressed to cut FL and FW. In 2015, the US announced a goal to reduce national FL and FW by half by 2030 [19].

FL and FW accounted for approximately 20% of food produced in the EU with a value of €143 billion in 2015 [20]. Household expenditure on food indicates how food is valued in di fferent countries. Household income spent on food in the EU is low as a proportion of income, on average 13%. By contrast, in several African countries, almost 50% of income is spent on food. The share of FW in Europe was a few percent in the 1930s but has increased sharply since then to current global levels where one-third of food produced is lost or wasted. The relatively cheap food in the EU gives little economic incentive for consumers to avoid waste. In addition to FW, plastic waste is also a major economic, environmental, and social challenge. The overwhelming majority of plastic packaging is used only once. In the food supply chains, materials, including packaging, should be reduced, reused, and recycled in the framework of the circular economy [21].

According to a market study, up to 10% of food waste generated annually in the EU is linked to date marking; however, the market survey showed a high level of compliance. The authors conclude that FW linked to date marking can be reduced with a clear and legible date mark and consumers can make the distinction between "use by" (indicator of safety) and "best before" (indicator of quality). Nevertheless, significant FW prevention in relation to date labelling can be achieved in the dairy, fresh juices, chilled meat and fish supply chain [22]. Misinterpretation of food date labels is one of the key factors leading to FW. Date labels on food in the USA show a large variety of forms such as "use by," "best before," "sell by," and "enjoy by" dates, which are poorly understood by consumers. This paper makes recommendations on changes to the date labelling system in the USA and addresses actions needed to clarify the issue [23].

A survey conducted in Italy showed three key factors defining the extent of household FW, namely socio-demographic characteristics (household income spent on food), food shopping patterns and consumer behavior. More education and information are needed for the prevention of household FW [24]. Another study identified measures to combat FW along the food value chain in the metropolitan region of Barcelona and stressed the relevance of more research, since stakeholders oppose the introduction of new regulations and policies. Future research on the impact of new regulation including strong FW prevention measures is needed to reach a consensus and willingness among stakeholders of the food supply chain to implement new policies [25].

Conrad et al. [26] analyzed the link between FW, diet quality, nutrient waste and sustainability in the US. Higher quality diets lead to higher FW associated with greater amounts of wasted irrigation water and pesticides but less cropland waste due to the increasing consumption of fruits and vegetables included in higher quality diets, which have lower cropland and higher input needs compared to other crops. The results of the study show that simultaneously improving diet quality and reducing FW is a complex issue. Fanelli [27] found similarities in the structure of the food supply in relation to the quantity of animal-based products. The environmental impact of agriculture depends mainly on the structures of the food supply and agricultural practices applied in the di fferent Member States of the EU. Consequently, large di fferences can be detected in the food supply of animal-based products and the GHG emissions intensity of the livestock sector. The farming system applied in the Member States should be based on the impact of agricultural practices on the environment to achieve a balance between livestock production and the intensity of GHG emissions. Furthermore, Fanelli [28] investigated the impact of agricultural activities on the environment in the Member States of the EU. She came to the conclusion that several Member States have similar production methods with a high impact on the environment; however, Mediterranean and northern Member States use traditional production methods including livestock grazing. Production methods with a high impact on the environment must be directed towards sustainable intensification.

The prevention of FW has become a global issue. In order to achieve this goal in developing countries a higher budget is needed for education, training and communication, technology implementation, and better infrastructure. Collaboration and dialogue between stakeholders along the food supply chain is crucial. Furthermore, data collection and comparable figures for di fferent countries are needed, as well [29]. Ishangulyyev et al. [30] emphasized that FL and FW are complicated issues involving multi-stakeholders along the food supply chain; therefore, more research, collaboration, and awareness is needed for the prevention of FL and FW. Authors focus on awareness of the impacts of FL and FW leading to changing consumer attitudes and behaviors.

In China, Gao [19] reported an annual loss of 7.9 mt for rice, wheat, and maize, but with advanced storage management, this can be reduced substantially. In India, the annual losses are estimated at 12–16 mt; however, losses are much higher at traditional farms, where 60–70% of the harvested grain is kept in short term storage facilities [31]. According to estimates by the FAO, in India the general FL and FW is around 40%, but for cereals 30% [32]. In the developing countries almost all pre-harvest and and post-harvest operations are conducted manually, therefore post-harvest loss accounts for 15% in the field, 13–20% during processing, and 15–25% during storage [33]. Smallholder farmers generally use conventional grain storage facilities, which are not e ffective against insects and mold. The replacement of these traditional storage structure with improved storage systems will maintain crop quality, reduce grain losses and food insecurity [34]. Up to 50–60% of cereal grains are lost during storage due to the traditional storage structures. Modern storage structures can reduce these losses up to 98%, thereby increasing food security [35]. In Jordan, the total loss and waste along the wheat supply chain amounts to 34% associated with significant of losses of natural resources. Among postharvest losses, consumer waste ranks first, accounting for 13% [36].

### **3. Materials and Methods**

Several methodological approaches can be used to identify household FW. Multivariate statistical techniques (descriptive statistics, principal component analysis, and hierarchical cluster analysis) were conducted to study the similarities and di fferences—namely the links between the structure of the food supply and the impact of agricultural practices on the environment between EU Member States [25]. Another study performed an exploratory online survey using a questionnaire adapted for studies on FW [24]. Furthermore, multivariate analyses was carried out for a comparative analysis of the environmental characteristics of the EU Member States with di fferent agricultural systems [26].

The causes and prevention of losses along the grain supply chain is shown, based on the review of relevant literature and combining results from relevant studies and global models. Various combinations of the following terms were used to search in various papers: preharvest losses, postharvest losses, prevention of losses, plant breeding solution, sustainability. The literature on food security is already substantial; however, grain losses across the supply chain have not been addressed in detail. Furthermore, there is a lack of available publications relating to the causes of preharvest and postharvest grain losses. In addition, we also conducted supplementary searches by examining bibliographies of articles for additional references. The references of the paper mainly cover the period 2001 to 2019. References might di ffer in their focus on potential or realized FL and FW, their use of di fferent baselines for comparisons, and other background conditions.

The FAO, OECD, International Grains Council, EU, and many other institutions publish serial data on grain production, use, trade, and prices. Other international sources issue estimates or data on grain losses before and after harvest. However, these data and information have not been aggregated and combined to make comparisons in order to calculate the benefits and trade-o ffs of grain production and losses at a global level. Data on food security related to production and losses have not been embedded into a global perspective. This paper attempts to combine all information collected to obtain a clear picture on the issue, which may serve the interests of multi-stakeholders along the grain supply chain. Other losses in the grain supply chain—losses in the conversion of feed into animal products, processing losses and over-consumption—have not been included in the calculation of grain losses and waste, and soybean losses and waste have also been excluded from our calculation.

### **4. Global Grain Production**

Worldwide, wheat, maize, and rice are the most important cereal grains, and soybean is the major oilseed grain. The production volume and projected yield growth of grains are closely related to food security. The consumption of grains is projected to exceed supply, while supply is expected to grow at a higher rate than demand in the midterm (Table 1). Borlaug [37] also reported an increase in the deficit of grain production compared to consumption, primarily in developing countries. According to the forecast of the International International Grains Council [38], yield increase is expected to grow from 0.8% to 1.5% annually from 2013/2018 to 2020/2024.

On the other hand, the increase in consumption is projected to decrease from 2.1% to 1.0% on average in the same period. So, the gap between the supply and demand of grains is shrinking leading to a decreasing accumulated deficit of about 155 million tons (mt) between production and consumption over the period of 2017/2018–2023/2024. The consequence of the downward trend in supply is a fall in the carry-over stock level from 29% to 21% between 2017/2018 and 2023/2024, making supply in critical years more problematic. However, data on supply and demand between years may vary strongly. Grain prices are expected to be higher than in past years in both real and nominal terms due to shrinking stock levels. This means that a robust increase in production cannot be expected; therefore, we should investigate how to feed the global population and livestock. The yearly change for the next years (y/y) is projected at 1.5% for production, 1.0% for consumption and 1.5% for exports accompanied by a slow decrease of carryover stocks. For this reason, much greater attention must be given to losses along the food chain.

**Table 1.** Forecast for global grain production (wheat, corn, rice and soybean), 2017/2018–2023/2024 (million tons).


Source: International Grains Council [38].

On the production side, further substantial increases in yield will be constrained. Obviously, technology, plant breeding, improving agronomy, and new production methods will resolve this phenomenon to a certain extent. Higher yielding cultivars are on the market, but their e ffect on yield is only moderate as the genetic capacity of these cultivars is just partly exploited. Without making long-term predictions of the global grain supply the problem described above must be approached from a di fferent perspective. We have to focus on causes and solutions of food and feed losses along the grain supply chain.

### **5. Losses along the Grain Chain**

The reduction of grain losses by biotic factors (pests, pathogens and weeds) is a major challenge for food supply [39]. In addition to pre-harvest losses, the losses occurring during transport, pre-processing, storage, processing, packaging, marketing and plate waste are also substantial (Figure 2). Reduction of losses results in a higher revenue than an increase in genetic yield ability [40]. Globally, an average of 35% of potential crop yield is lost to pre-harvest pests [41]. In addition to pre-harvest losses, the losses occurring during transport, pre-processing, storage, processing, packaging, marketing, and plate waste are also substantial [39]. By reducing FL and FW, food security combined with resource e fficiency can be enhanced. In 2011 the European Commission set targets to halve the disposal of edible FW by 2020, and in 2012, the European Parliament also issued a resolution to halve FW by 2025 and designated 2014 as the "European Year against Food Waste" [42,43]. The problem is that the EC targeted only edible FW excluding other forms of waste, for example in feeding.

**Figure 2.** Losses along the food chain. Source: International Water Management Institute [44].

Each stage of the grain value chain is a source of grain losses and waste, each with a different loss ratio. The problem needs a multidisciplinary approach [45,46], but in spite of efforts we are far from the solution. Therefore, our goal was to summarize losses along the grain value chain and identify more effective solutions. The increasing loss and waste of grains reduce food security and also negatively affect sustainable development (natural resources, environment and human health) [47,48]. In addition to the actual loss and waste, resource inputs, e.g. arable land, irrigated water, fertilizer and energy, are also lost and wasted Gustavsson et al. [11] contributing to higher cost for a unit of really consumed product.

In 2018, global grain production accounted for 2.102 million tons [38]. The data we used for losses are based on estimates in the literature. However, the different sources produce comparable numbers. We used the lower estimates for increased reliability. It is well known that the loss expressed in monetary term is very high at lower quality or high toxin contamination even the amount of losses does not change much. For example, toxin contamination can cause 100% income loss at minimal yield reduction. Approximately one-third of potential crop yield is lost to pre-harvest pests, pathogens and weeds. The theoretical yield would account for 3.153 mt per annum and pre-harvest losses amounts to 1.051 million mt. Grain losses at harvest are estimated at 3% or 60 mt annually, with wide regional variations between small and large farms. Total pre-harvest and harvesting losses account for about 1.110 mt per year. In addition, 420 mt of grains are lost during storage, 210 million tons due to field mycotoxin contamination (excluding consumer's waste of 286 mt annually (Table 2). It can be concluded that one third of the possible yield is lost before harvest, another 20% is wasted due to storage and mycotoxin contamination, and only one third of the grain total production potential is really consumed, including consumer waste of around 10%).


**Table 2.** Losses of grains along the full value chain in 2018 (million tons).

Source: Authors' own calculation based on the production data of International Grains Council [38].

### *5.1. Field (Pre-Harvest) Losses*

Yield losses caused by pests, pathogens, and weeds are major challenges to crop production. Increased use of plant protection increased crop harvests from 42% of the theoretical worldwide yield in 1965 to 70% of the theoretical yield by 1990; however, at least 30% of the theoretical yield was still being lost due to ineffective pest-management methods applied in several regions of the world. Without plant protection, 70% of crop yields could have been lost to pests [41]. Actual losses were estimated at 26–30% for soybean and wheat, and 35%, and 40% for maize and rice, respectively [40]. Cramer [49] estimated crop losses of around 28% due to all pests in North and Central America. Russel (1978) cited over 50% yield losses caused by pests, pathogens and weeds worldwide. Schumann and D'Arcy [50] estimated the loss of yield caused by all pests at some 20% despite the billions of dollars spent on plant protection. According to Ubrizsy [51], in the 1960s mean yield loss for all crops caused by pests, pathogens and weeds stood at 15–20% and 25–30%, respectively. Actual losses were estimated at 36% for wheat and 38% for maize on average during the period 1950–1960 excluding yield loss caused by abiotic factors (temperature, humidity, rain, floods, etc.).

It is well known that plants would not survive a crisis-level water shortage because under a certain level of precipitation plants cannot cope with water stress. In Hungary, yield sensitivity to droughts show that maize and wheat yield reduction may reach up to 50% in drought seasons. The effects of drought play a large role in damage to crops, depending on soil quality. Drought conditions can have a moderate impact on good soil or a profound impact on sand. The yield loss in drought and dry seasons reaches one-third on average. Beyond the 35% loss due to biotic factors, we did not count extra losses for abiotic losses, as in drought years, diseases, insects, and weeds normally cause significantly less damage. The authors aimed to make a conservative estimate that is close to reality. Aflatoxin is an exception in draught and hot years, but in yield reduction it is not important.
