1. Introduction
Given its various beneficial health properties, olive oil is one of the most important agri-food products. According to the International Olive oil Council, the world’s olive oil production reached 3.01 million tonnes in 2020-21, of which about 68% was produced in the European Union [
1]. Spain was the largest contributor country with about 46% of the total production, followed by Italy and Greece, both with 9.1% [
1].
Due to the relevance of this agri-food product, several studies have analyzed the olive oil supply chain focusing on its energy, economic, and environmental aspects [
2,
3]. From the environmental point of view, the sustainability evaluation of the olive oil sector was mainly performed with the adoption of the Life Cycle Assessment (LCA) methodology [
4,
5]. LCA allows an estimation of the environmental impacts that can occur during all the life cycle phases of the product, taking into account resources and energy consumption as well as any pollutant emissions and waste produced [
6,
7]. LCA studies on olive oil highlighted that the agricultural phase is responsible for the highest environmental impacts of the olive oil life cycle [
8,
9], followed by the packaging phase that provides a significant contribution to the overall impacts [
10,
11] mainly due to glass bottle production and transportation [
12].
Nevertheless, the glass bottle is the most widely used packaging for virgin olive oil (VOO) in many countries, including Italy [
13]. This is mainly due to the high reputation of glass packaging amongst consumers, who tend to associate the weight and type of packaging material with a higher quality of the food contained [
14,
15]. Despite this, some packaging alternatives for VOO (such as polyethylene terephthalate (PET) bottle, bag-in-box, and tin-plated steel container) have proved to be suitable for packaging VOO and are available on the market. Some studies analyzed the VOO quality level in different packaging solutions under various temperature and lighting conditions [
16,
17], highlighting that, although glass is the best material for long-term storage, dark-colored PET guarantees the maintenance of the VOO quality level for six months with temperatures less than or equal to 22 °C [
18,
19].
Other LCA studies compared the environmental performances of packaging alternatives, including glass bottles and PET bottles, for different types of food and beverages such as soft drinks [
20,
21], wine [
14,
22], water [
23,
24], etc. Most of the papers showed that the PET bottle generates lower environmental impacts during its life cycle than those of the glass bottle. Focusing on the global warming issue, Kouloumpis et al. (2020) [
25] highlighted that to achieve comparable impacts for glass and PET, glass bottles need to be 40% lighter. The environmental benefits of PET bottles are even higher with the use of recycled PET (R-PET) bottles as shown by some LCA studies that assessed the environmental performances of R-PET bottles and glass bottles for water [
26,
27] and milk [
28].
Nevertheless, few LCA studies have considered PET bottle as a packaging alternative for VOO. Navarro et al. (2018) [
15] applied LCA to the environmental comparison of different VOO packaging (glass, PET, and tin), pointing out that the most sustainable alternative was a PET bottle. Similar findings were presented in the study by Salomone et al. (2013) [
29] where the authors performed a LCA analysis of glass and PET bottles for VOO packaging. However, the two previous studies on EVOO packaging analysed PET produced with only virgin PET granulate.
Considering R-PET, to the best of our knowledge, only the paper by Accorsi et al. (2015) [
30] carried out an environmental assessment of this type of packaging for VOO, comparing it to virgin PET and glass bottles. The authors showed that the glass bottle was a better packaging alternative mainly due to the high recycling rate of glass; however, the R-PET bottle obtained the lowest impact in the global warming category [
30]. Nevertheless, Accorsi et al. (2015) [
30] focused on R-PET bottles produced with 50% of recycled PET granulate, since this percentage was the permissible limit value of the use of recycled granulate in new bottles for food packaging set out by Italian policies and rules [
30].
Table 1 reports the main details of the above-mentioned LCA studies concerning the comparison of the environmental performances of the PET and glass packaging systems.
Currently, under Italian Law No. 178 (30-12-2020; State Budget for the financial year 2021) [
31], it is permissible in Italy to produce PET bottles for food using 100% recycled PET granulate, and, to the best of our knowledge, no LCA study has assessed R-PET bottles produced with 100% of recycled PET for VOO packaging. Even if some Italian producers of VOO are already using such packaging, it can mainly be found on foreign markets.
Therefore, this paper provides a contribution by presenting a comparative LCA of two different packaging systems for extra-virgin olive oil (EVOO): a glass bottle and a recycled PET (R-PET) bottle (produced with 100% of recycled PET). The study also focuses on the EVOO distribution phase, showing its impact contribution in function of the different packaging considered for different distances and logistics.
2. Materials and Methods
2.1. Extra-Virgin Olive Oil Packaging Systems
The environmental performances of two different packaging systems for EVOO were compared: glass bottles (produced with 77% of recycled glass) and R-PET bottles (produced with 100% of recycled PET). Both systems are used by an important EVOO company located in Southern Italy, which provided most of the primary data used in the study.
The two systems were compared also in function of three different distribution markets of the company: Switzerland, Denmark, and China. EVOO distribution in these countries varies in terms of both transport distances and logistics. The company distributes its products mainly by truck to Switzerland and Denmark, and by ship to China.
Six scenarios were defined (showed in
Figure 1), in function of the type of packaging system and EVOO distribution country.
The primary packaging of the systems includes bottles, PE labels, and caps (made of PE-Aluminum for the glass systems and only of PE for the R-PET systems). All these components, except the R-PET bottles, are produced in packaging companies and transported to the EVOO plant. The R-PET bottles are obtained via a blow-molding process starting from PET preforms, directly in the plant.
After the bottling phase, the bottles of both systems are capped and labelled and placed in cardboard boxes (secondary packaging). The boxes are then put on wooden pallets and covered with cardboard protective layers and PE stretch film. At this stage, the EVOO is ready for distribution.
2.2. Life Cycle Assessment Approach
The main aim of this study was to compare the environmental performances of two packaging systems for EVOO through LCA analysis to identify the most environmentally sound alternative for different distribution markets and to highlight the most important hotspots of the life cycle phases of the systems.
In agreement with other LCA studies on the topic, the functional unit (FU) of the study (i.e., a quantified description of the performance requirements that the product system fulfils) was defined on the basis of a volume of EVOO [
15,
32]. In detail, the FU of the study was all the primary, secondary, and tertiary packaging components required for the bottling and distribution of 1000 L of EVOO.
The LCA was performed following a “cradle to grave” approach, therefore the system boundaries of the study included all the life cycle phases of the packaging systems except the use phase, from the raw material processing to the packaging components’ final disposal and including all the transport steps (
Figure 2).
For the two systems compared, all the components of the primary, secondary, and tertiary packaging were considered.
The production phase was modelled with the following assumptions based on the data and information provided by the EVOO company:
- -
R-PET bottles and glass bottles were produced with 100% and 77% of recycled material, respectively.
- -
All the other components of the primary, secondary, and tertiary packaging of the two systems were produced with 100% virgin materials (except the cardboard components).
- -
For the cardboard boxes and sheets, a recycled content of 80% of recycled fibers was assumed.
- -
The production of the wood pallets was not included in the study because they were reused many times and are the same for the two packaging systems.
The EVOO distribution phase was modelled considering three destination markets of the company that differ according to transport distances and logistics (mainly by road for the European markets and mainly by sea for the Chinese market).
Data related to transport distances between the plant site and the capital cities of the distribution countries was used. Local EVOO distribution in each country was not considered.
Regarding the end-of-life phase of the packaging systems, disposal scenarios for all the packaging materials were defined. They were composed of landfilling, incineration, and recycling. Waste transport to the disposal plants was not considered.
The LCA models were performed with the use of the SimaPro 8 (Pre Consultants, Amersfoort, The Netherlands) software tool.
The EVOO company provided primary inventory data about the following:
- -
packaging production processes;
- -
transport of all the packaging components to the plant;
- -
EVOO bottling operation and packaging assembly;
- -
EVOO distribution to the three countries.
The Ecoinvent v.3 database was the main source for background inventory data about the infrastructure and vehicles, Italian energy mix, extraction, and processing of raw materials and fuels.
Table 2 and
Table 3 report the main data about the weight and composition of the packaging components of the two systems as well as data on the transportation of these components to the EVOO company.
Regarding the distribution phase modelling,
Table 4 reports the vehicle types considered and the data expressed as weight in tons of each packaging system (excluded oil weight, which was the same for the two systems) multiplied by the distance in km for each destination country.
For the end-of-life phase of the packaging systems, different modellings were performed based on the country considered for EVOO distribution.
For the four scenarios that considered European countries (S1 G_CH; S2 P_CH; S3 G_DK; S4 P_DK), the landfilling, incineration, and recycling processes for each packaging material were modelled based on the data reported in
Table 5. Eurostat was the data source for the percentage values of the three disposal treatments for each material and are referred to in the European disposal scenario of packaging in 2019.
Regarding the other two scenarios (S5 G_CN; S6 P_CN), the same level of detail of the data for the Chinese disposal scenarios of packaging waste was not available; therefore, incineration with energy recovery were assumed for all the packaging materials, considering that in China the main municipal solid waste treatment is incineration (more than 50%) [
33,
34].
The life cycle impacts of the two packaging systems were estimated using the ReCiPe 2016 evaluation method with a hierarchist (H) perspective [
37]. Due to its holistic approach that allows the consideration of several environmental issues, ReCiPe is one of the most-used methods in LCA studies on food packaging [
14,
22,
28]. The method allows the use of two approaches: the midpoint (problem-oriented) level with 18 impact categories and the endpoint (damage-oriented) level with three macro-categories (damage to human health, damage to ecosystems, and resource consumption) [
37].
Both approaches were used in this study, and a part of the analysis focused on the most representative midpoint categories, selected following the same procedure reported in other similar studies [
14,
22,
38], namely those impact categories that provided the highest contribution to the three damage categories at the endpoint level. The most relevant midpoint categories were the following: global warming potential (GWP), fine particulate matter formation (FPMF), terrestrial acidification (TA), and fossil resources scarcity (FRS).
3. Results and Discussion
Figure 3 shows a comparison of the environmental performances of all the assessed scenarios for the two EVOO packaging systems (glass bottles (S1_G); R-PET bottles (S2_P)) and for the three distribution countries considered (Switzerland; Denmark; China). The results are expressed in percentage terms in function of the systems with the highest impact values and estimated with the midpoint categories of the ReCiPe 2016 H evaluation method.
In agreement with other LCA studies on the topic, the glass system was responsible for much higher impacts than the R-PET system in all the impact categories [
28]. The differences between the impacts of the two systems were higher than 40% for most categories (
Figure 3). Similar results were also shown by Navarro et al. (2018) [
15], although their impact gaps between glass and PET were slightly lower, maybe due to the use of virgin PET granulate in the PET bottle production.
Looking at the three different distribution distances, the results show that from an environmental point of view, distributing EVOO produced in Southern Italy and packaged in the R-PET system in China (18,000 km) or in Denmark (2114 km) was more sustainable than distributing EVOO in the glass system in Switzerland (1000 km)
Very similar results were obtained when estimating the impact values with the endpoint approach of the ReCiPe 2016 H method, as reported in
Table 6.
As previously discussed by Espada-Aldana et al. (2019) [
12], the glass bottle system was the less sustainable packaging solution not only during the distribution phase but also in the packaging production phase [
12]. This was mainly due to the higher weight per bottle of glass than PET (an empty glass bottle for EVOO is more than seven times heavier than a R-PET bottle); a higher weight means more material to produce, with a higher energy and resources consumption, and more material to transport, with a higher fuel consumption [
28,
39]. Furthermore, it is worth noting that the wide gap between the environmental performances of the two packaging systems was also due to the different percentages of the recycled materials used in the bottles’ production processes: the glass bottles were produced with 77% of recycled glass and therefore required an amount of virgin materials; whereas the R-PET bottles (100% recycled PET) required no virgin PET granulate input.
These aspects are also underlined by the results shown in
Figure 4 that report the contribution analysis of the different life cycle stages of the two packaging systems for all the scenarios; estimated with the three endpoint categories of ReCiPe 2016 H method.
Although the production phase provided a significant contribution in both packaging systems, for glass, this phase was always responsible for the highest impacts in all the scenarios considered [
14,
39] mainly due to the resources and energy consumption required during the glass bottles’ production [
39,
40]. In contrast, distribution was the most impactful step for the PET system in most cases [
26].
It is worth noting that the end-of-life phase provided a different type of contribution for the two packaging systems. Negative contributions for the glass systems means environmental benefits, mainly due to glass recycling, which avoids virgin glass production [
15]. As reported in the European disposal scenario for the R-PET system (
Table 5), also for PET an amount of material was sent to recycling, however this process did not have the same environmental benefits due to the lower recycling rate of PET and the lower recycling efficiency compared to the recycling of glass [
24]. Accorsi et al. (2015) [
30] underlined that the high recyclability of glass involves significant environmental benefits in the end-of-life phase of this EVOO packaging solution. Similar results were reported also in the study of Kouloumpis et al. (2020) [
25], which highlighted the high sustainability of glass as a recyclable material. Indeed, glass can be recycled countless times without deterioration of the material quality [
25]. Furthermore, the amount of PET bottles sent to incineration provided a non-negligible contribution to the end-of-life phase of the PET system.
Different aspects emerged looking at the impacts of the end-of-life phases for scenarios S5 G_CN and S6 P_CN (that considered the EVOO distribution in China). For these scenarios, not even the end-of-life of the glass system brings benefits due to the assumption regarding the lack of recycling processes.
Looking at the most relevant impact categories at the midpoint level,
Figure 5 shows the environmental impacts, in absolute terms, of the six considered scenarios reporting the impact values of each life cycle phase. The production phase was divided into two sub-phases: primary and secondary-tertiary packaging production (1st Pack P and 2nd–3rd Pack P, respectively) to highlight the differences between the two packaging systems.
Looking at the first four scenarios (S1 G_CH; S2 P_CH; S3 G_DK; S4 P_DK) in which a EVOO distribution in European country was considered, the primary packaging production provided the highest contribution to the total impact for both the packaging systems in all the impact categories considered. Similar results were showed in the studies of Cleary (2013) [
22] and Stefanini et al. (2020) [
28].
In agreement with the study by Stefanini et al. (2020) [
28], secondary-tertiary packaging production generated higher impacts for the glass system compared to the R-PET system due to the higher number of auxiliary materials required for transport of the glass bottles. The weight and shape as well as the brittleness of the glass bottles led to a lower palletizing efficiency [
14]. Looking at the impacts in terms of global warming (GWP), for example, secondary-tertiary packaging for the glass system was responsible for 70.3 kg CO
2 eq./FU, while the same step provided a contribution of 24.9 kg CO
2 eq./FU for the R-PET system. These findings are in line with the GWP impacts reported in the study of Stefanini et al. (2020) [
28] relating to the secondary-tertiary packaging of glass and R-PET systems (90 g CO
2 eq and 37.7 g CO
2 eq., respectively, considering the packaging of 1 L of milk).
Focusing on the different distribution countries, the results showed higher environmental impacts with increasing distribution distance; however, for two categories (GWP and FRS), the impact values of EVOO distribution in China were lower than those in Denmark for both packaging systems, despite the higher distance to cover. The global warming impact scores of this phase for the glass system were about 310 and 503 kg CO2 eq./FU for EVOO distribution in China (CN) and Denmark (DK), respectively, while, looking at the fossil resources scarcity category, the impact contributions of this phase were 99.5 and 172.7 kg oil eq./FU for CN and DK distribution, respectively.
This occurred because of the transport type: for the EVOO distribution in Denmark, it was mainly assumed to be by truck, while for China by ship was the main distribution type. Usually, for the same amount of goods to be distributed, transport by ship is more efficient than by truck since it consumes less fuel and produces fewer pollutants emissions [
41].
Finally, from an environmental point of view, the R-PET system proved to be a better packaging solution for EVOO compared to the glass system. However, this aspect is not enough to drive for a greater adoption of this EVOO packaging alternative in the market. Other key factors should be considered such as consumers’ attitude toward this solution and, consequently, their willingness to buy EVOO packaged in R-PET. Usually, consumers tend to prefer glass bottles among all the packaging alternatives available [
15]. Literature studies on consumers’ attitude toward different beverage packagings showed that glass was considered the safest as well as the most sustainable packaging material [
42,
43,
44], highlighting the lack of or incorrect communication between the scientific community and citizens [
43].
Therefore, the findings of this study can help inform consumers about the environmental sustainability of the EVOO packaging solutions. Innovative communicative initiatives would be needed to allow consumers to go beyond prejudices and commonplaces and direct them towards more informed purchasing choices.
4. Conclusions
The life cycle impacts of two packaging alternatives for an extra virgin olive oil (EVOO) produced in Southern Italy were compared using the LCA methodology in order to identify the most sustainable packaging solution for different distribution markets. Six scenarios were assessed, defined based on the packaging system (glass bottles and R-PET bottles) and the country of EVOO distribution (Switzerland, Denmark, and China).
The results highlighted that the glass system always had the worst environmental performances for all the considered impact categories (both the midpoint and endpoint level of the ReCiPe 2016 H method), and this was mainly due to the high weight of the glass, which significantly affects the system production and distribution phases. The production of glass bottles provided the highest contribution to the total life cycle impacts of these packaging systems for all the considered impact categories. Furthermore, compared to the R-PET systems, glass packaging required a higher amount of secondary-tertiary packaging and allowed for a lower palletizing efficiency. Therefore, the R-PET system was the most sustainable alternative for all the three EVOO distribution markets taken into consideration. However, in the end-of-life phase, the glass system reached higher environmental benefits compared to the R-PET system, due to its higher recycling rate and efficiency. Logistics affected the impacts of the distribution phase, showing that transportation by ship was more sustainable than by truck even when considering the greater distribution distances. This occurred since for the same amount of goods to be distributed, transportation by ship consumed less fuel and produces fewer pollutants emissions.
The results of this LCA study can be used to direct consumers towards more informed choices with a view to sustainability, while also helping disprove the prejudices that consumers often have towards packaging alternatives to the glass bottle.
Limitations of the Study and Future Researches
The study assessed the environmental performances of two EVOO packaging systems through the application of the LCA methodology. Therefore, the obtained results showed only the life cycle environmental impacts of the systems, while the economic and social aspects of the sustainability are missing. Nevertheless, for an effective sustainability assessment of alternative systems, the environmental, economic, and social aspects should be integrated [
39]. In this sense, next to the LCA methodology, very useful tools as Life Cycle Costing (LCC) and Social Life Cycle Assessment (SLCA) are available to estimate the economic and social impacts, respectively [
45]. Therefore, it would be interesting to carry out future research in order to assess the sustainability of EVOO packaging alternatives by integrating the three aspects.
Furthermore, future studies could contribute to the topic by combining the LCA methodology with other sustainability assessment tools such as energy, emergy, and exergy analysis. For instance, the study of Aghbashlo et al. (2022) [
46] showed that the integration of more methodologies can provide more reliable results than single approaches.