A case study in Spain to optimize the environmental sustainability of fresh vegetables postharvest?

The aim of this research is to define different scenarios that optimize the environmental sustainability of the post-harvest stage of vegetable products (cauliflower and brassicas mix). These scenarios considered different packaging materials; energy generation technologies for the processing plant (standard electricity mix vs. renewable options); organic waste management (composting, anaerobic digestion, and animal feeding); and refrigerated transportation (local, national, and international, using diesel, natural gas, and hybrid trucks and railway). The analysis has been carried out based on a foreground inventory provided by a company that operating internationally, in accordance with the International Organization for Standardization (ISO) 14,040 methodological framework and following the latest Product Environmental Footprint (PEF) protocols. The analysis describes four midpoint categories, single score (SS) using EF3.0 life cycle impact assessment (LCIA) methodology and the Cumulative Energy Demand. The carbon footprint (CF) of the post-harvest stage for a base case scenario ranged between 0.24 and 0.29 kg CO2 eq/kg of vegetable, with a strong contribution associated to the production of packaging materials (57.8?65.2 %) and the transport stage (national range in conventional diesel vehicles) (31.5?38.0 %). Comparatively, lower emissions were associated with the energy consumed at the processing factory (up to 4.1 %) while the composting of organic waste management produced some impact savings (up to ?3.5 %). Although certain differences were observed, the dominance of the transport stage and the packaging materials is sustained in all the other environmental impact and energy categories evaluated. The most effective measures to reduce the environmental footprint of the post-harvest stage involve: i) using reusable packaging materials; ii) reducing the transport range and using vehicles running on natural gas or hybrid technologies; iii) the incorporation of renewable energy to supply the factory; and iv) the utilization of the organic residues in higher value applications such as animal feeding. Implementing the measures proposed in this study would reduce the post-harvest CF of fresh vegetables by 90 %. The?text before are the abstract. Introduction1. IntroductionAbout 21?37 % of all anthropogenic greenhouse gas (GHG) emissions are associated with food systems. These do not only arise from the agricultural activities needed to produce food commodities (9?14 %), but also derive from land use and land-use changes (LULUC) (5?14 %) and other activities that take place downstream of the agricultural stage to complete the food supply chain (5?10 %) (e.g., food storage and cooling, transport, packaging, processing, retailing, and final use) (Mbow et al., 2019). A continued increase in the environmental pressure exerted by food and agricultural systems is expected in the coming years as the Food and Agriculture Organization (FAO) estimates a 50 % increase in food production by 2050 due to a growing population and global dietary improvements (FAO, 2018). Spain is the largest producer of fresh fruit and vegetables in the European market with over 28 Mt. in 2020 (MAPA, 2021a) The Region of Murcia, in south-eastern Spain, is the leading producer of cauliflower (31,146 t/year) and broccoli (206,600 t/year), representing 13.2 % and 36.5 % of the total national output, respectively, and occupying over 13,750 ha of agricultural land (MAPA, 2021b). In a global situation marked by the climate crisis and the degradation of natural ecosystems, process-based life cycle assessment (LCA) has been postulated as a particularly useful tool for evaluating the environmental performance of consumer products and services. This applies to agricultural systems, which have been extensively studied following the standardized framework of the International Organization for Standardization (ISO) 14040:2006 (ISO, 2006a). Most of those studies focus on the production phase (pre-harvest), and have been published in the form of scientific papers, Environmental Product Declarations (EPD) and in background Life Cycle Inventory (LCI) databases specialized in food and agriculture products, such as Agribalyse (Colomb et al., 2014), Agri-footprint (Durlinger et al., 2014), Quantis World Food LCA Database (WFLDB) (Bengoa et al., 2019), and ESU World Food LCA Database (ESU Services, 2021). Regarding the pre-harvest stage of the vegetables considered in this study (cauliflower and broccoli), the scientific literature describes Carbon Footprint values (CF) ranging from nearly zero (0.01 kg CO2 eq/kg) (Romero-G?mez et al., 2014) for scenarios characterized by minimal human contribution, up to 0.25 kg CO2 eq/kg (Bartzas et al., 2015; Maraseni et al., 2012; Martin-Gorriz et al., 2020, Martin-Gorriz et al., 2014; Pereira et al., 2021; Persiani et al., 2019). The differences reported are associated primarily with differences in the irrigation process regarding water source (rain, river, well), abstraction technology (gravity, mechanical, electric pumping, etc.) and irrigation technology (sprinkler, drip, etc.), cultivation system (open-field, greenhouse, hydroponic, rotation crops, intercropping, etc.), fertilization requirements, degree of mechanization and production yields. Less scientific effort has been dedicated to assessing the environmental performance of processes downstream of this agricultural stage, although its contribution to the value chain of food systems is by no means negligible. These post-harvest processes include handling (sorting and/or sizing) and processing, packaging, storage, cooling and transport to the final consumer, including the management of organic residues and packaging components at the end of their useful life (Boschiero et al., 2019). Table 1 describes selected publications which have calculated the LCA or CF of different fruit and vegetables throughout their value chain under different impact assessment methods, where ?cradle-to-market? considers the delivery of the products to the retailer as a downstream boundary, and ?cradle-to-grave? also incorporates the impacts generated by the end consumer. This table compiles the CF of these products standardized for the same functional unit (1 kg) and the contributions per main stages. Liu et al. (2010) reported minimal carbon emissions (0.06 kg CO2 eq/kg) in locally consumed fruits from rainfed woody crops produced with organic fertilization and hand sorting. The highest CF (up to 2.2 kg CO2 eq/kg of broccoli) were determined for vegetables produced using intensive agricultural practices that involved energy-intensive mechanization (Ingwersen, 2012); electricity consumption for irrigation and fertigation (Liu et al., 2010; Payen et al., 2015; Peano et al., 2015; Rana et al., 2019); consumption of fertilizers and agrochemicals (Iriarte et al., 2021); the use of auxiliary infrastructures, such as greenhouses and plastic covers (Payen et al., 2015; Rothwell et al., 2016); refined processing and packaging and long range refrigerated transport (Canals et al., 2008). Table 1 shows a strong variability in the contribution of the agricultural phase to the overall environmental performance of the vegetable products (between 7.4 % and 75 % of total CF). It should also be noted that some of the results reported in these studies could be questioned, since they do not apply the latest protocols for the analysis of biobased products (e.g., European Commission - Product Environmental Footprint (PEF)) (Zampori and Pant, 2019) and consider plant products as CO2 sinks. The post-harvest stage considers the processes that take place in the vegetable processing plant and include product reception, handling (sorting and/or sizing), packaging and cold storage prior to shipping to the retailer and final consumer. From the results shown in Table 1, the contribution of this processing plant to the overall CF of the vegetable product varies considerably (between 3.5 and 54 %), depending on the net emissions associated with other life cycle stages and the processing requirements of the product considered. Two factors contribute most to the CF of this factory phase: the production of the packaging material (Canals et al., 2008; Ingwersen, 2012; Payen et al., 2015; Peano et al., 2015; Rana et al., 2019; Rothwell et al., 2016; Svanes and Johnsen, 2019), and the electricity consumed in cooling operations (Liu et al., 2010; Parajuli et al., 2021; Rana et al., 2019; Iriarte et al., 2021). The contribution of the transport phase also varies greatly, being mainly influenced by the distance and means of transport (highest emissions per km?t for refrigerated road transport and lowest for sea and rail) (Boschiero et al., 2019). For road transport, fuel type has also been reported to influence environmental performance, with heavy-duty vehicles powered by compressed natural gas (CNG) and electric/hybrid technologies exhibiting lower CF than diesel vehicles (Gustafsson et al., 2021; Ravign? and Da Costa, 2021; Rial and Javier, 2021; Wolfram and Wiedmann, 2017). Thus, the transportation stage in locally consumed pears (Liu et al., 2010) and lettuce (Rothwell et al., 2016) contributed to only 0.7 % and 3.5 % of the total carbon emissions of those products, respectively. In contrast, refrigerated international road transport of sweet cherries (Svanes and Johnsen, 2019) or lettuces (Rothwell et al., 2016) caused contributions of 14.5 % and 22.0 %, respectively. The contribution of transport in the refrigerated transoceanic shipping of apples (13,890 km) amounted to 71.7 % of their total CF (Iriarte et al., 2021). Girotto et al. (2015) and Papargyropoulou et al. (2014) described the relationship between food waste and environmental footprint. The contribution of the End of Life (EoL) phase depends largely on the quantity and type of the by-products generated, and also the management scenarios considered. Thus, some authors have described small emission savings (? 0.5 %) due to the credits generated by the use of organic residues for animal feeding (Parajuli et al., 2021). Other authors described significant CF contributions (up to 16.3 %) as they considered emissions derived from human excretions and wastewater treatment requirements (Canals et al., 2008). Most of the food waste is landfilled, contributing not only to direct CF emissions but also to water pollution due to nitrogen (N) and phosphorus (P) leaching. Utilizing these residues for other commercial purposes reduces the impact of the food products throughout their value chain and may also provide a source of income that sustains the economic viability of the product. One option is to use food residues as animal feed (Ferguson, 2019). The FAO (2021) reported that 1.25 billion tons of food waste were used as animal feed. Other applications for food by-products include composting and energy valorization through anaerobic digestion for biogas production (Rojo et al., 2021) or direct combustion (Prasad et al., 2020). Cherubin et al. (2018) estimated that European food and crop residues could produce up to 12,528 MBTU (Mega British Unit) of energy. In this context, the aim of the present study is to quantify the environmental impact of the post-harvest stage of two fresh vegetable products, representatives of the horticultural sector, that are widely produced and consumed in south-eastern Spain, and extensively exported throughout Europe. These results should identify those processes contributing the most to the environmental performance of these products and have the greatest potential for improvement. A more detailed description of these objectives is included in Section 2.1. Goal definition, as required by ISO 14040 (ISO, 2006a). This research aims to perform a holistic assessment of the fresh vegetable post-harvest production system to optimize its environmental performance. Contents2. Methodology2.1. Goal definition2.2. Scope definition2.2.1. Methodological structure2.2.2. System description and system boundaries2.2.3. Description of base case and advanced scenarios2.2.3.1. Energy scenarios at the processing factory2.2.3.2. Packaging scenarios2.2.3.3. Vegetable waste management scenarios2.2.3.4. Transport scenarios2.2.4. Functional unit2.2.5. Multifunctionality and allocation2.2.6. Environmental impact assessment methodologies and impact categories2.2.7. Inventory data collection2.2.8. Others2.3. Life cycle inventory analysis2.3.1. Inventory data for packaging materials2.3.2. Inventory data for the processing factory2.3.3. Inventory data for vegetable waste management (EoL)2.3.4. Inventory data for transport3. Results and discussion3.1. Environmental assessment of the base case scenario3.1.1. Characterized impacts3.1.2. Normalized and aggregated post-harvest impacts assessment3.2. Environmental assessment and advanced scenarios of packaging3.3. Environmental assessment and advanced scenarios of processing factory3.4. Environmental assessment and advanced scenarios of organic waste management3.5. Environmental assessment and advanced transport scenarios3.6. Uncertainty analysis4. ConclusionsPicture is the graphical abstract SourceOptimizing the environmental sustainability of alternative post-harvest scenarios for fresh vegetables: A case study in SpainLaura Rasines, Guillermo San Miguel, ?ngel Molina-Garc?a. Francisco Art?s-Hern?ndez, Eloy Hontoria & Encarna AguayoScience of The Total Environment, Volume 860, 20 February 2023, 160422https://www.sciencedirect.com/science/article/pii/S0048969722075246?via%3Dihub?https://doi.org/10.1016/j.scitotenv.2022.160422?