Postharvest Losses in Quantity and Quality of Pear (cv. Packham’s Triumph) along the Supply Chain and Associated Economic, Environmental and Resource Impacts

: Approximately one third of the food produced globally is lost or wasted along the supply chain. Reducing this would be an important measure to increase the global food supply as the world continues the struggle to feed its people sustainably. Not merely a waste of food, these losses also represent a waste of human effort and agricultural inputs from expensive fertilizers to natural resources as well as contributing to global greenhouse gas emissions. Measuring the extent of, and understanding the reasons for, these losses can assist in developing appropriate measures required to prevent or reduce such losses. Therefore, the objective of this research was to quantify postharvest losses in quantity and quality of ‘Packham’s Triumph’ pears at farm and simulated retail levels. Pears were sampled from two farms in the Western Cape Province of South Africa, the largest deciduous fruit production and export region in Southern Africa. The greatest losses measured along the supply chain were on-farm immediately after harvest, with 18% recorded. The main reasons for on-farm losses were small size (65%), deformity (26%), and chafed peel (9%). After 14 days in cold storage ( − 0.3 ± 0.7 ◦ C, 81.3 ± 4.1% RH), mean pear losses were 0.86% which increased to 1.49% after 28 days. After 10 days of further storage under simulated market conditions (5.4 ± 0.6 ◦ C, 83.7 ± 2.9% RH), fruit losses were 1.52% during retail marketing and 2.09% during export. Storing pears under ambient conditions (25.1 ± 1.3 ◦ C and 46.6 ± 6.0% RH) resulted in a higher incidence of losses, increasing from 0.90 to 1.55 and 2.25% after 3, 7, and 10 days, respectively. The socio-economic impacts of these postharvest losses amounted to ﬁnancial losses of between ZAR 492 million (USD 34.1 million according to the conversion rate of 14 April 2021) to over ZAR 831 million annually, and this was associated with the loss of 301 million MJ of fossil energy, 69 million m 3 of fresh water and contributed to the emission of approximately 19,690 tons of CO 2 equivalent. The fresh water lost could sustain 3.7 million individuals daily for a whole year at a daily minimum usage rate of 0.05 m 3 per day while it will require planting 0.5 million trees to sink the 19,690 tons GHG emissions of the pear losses (0.039 metric ton per urban tree planted). Decreasing postharvest losses will conserve resources as well as improve food security and nutrition, objectives of the post-2015 sustainable development agenda led by the United Nations.


Introduction
Around one billion people are currently malnourished as the world continues to struggle to feed its people sustainably [1][2][3]. The projected increase in the global population

Harvesting and Sampling Techniques
Harvesting and Sampling Techniques Data collection protocols were similar to those used by [24]. Pears were collected during the commercial harvest on 5 February 2018 at Lourensford farm (latitude: 34 • 04 S longitude: 18 • 53 E) in Somerset-West and on 20 February 2018 at Uitvlugt farm (latitude: 34 • 22 S; longitude: 20 • 34 E) in the Overberg area. Both farms are located in the Western Cape, South Africa. At harvest, ten full 20 L picking bags were selected at each farm and the contents were carefully inspected to quantify the percentage of fruit that would be discarded due to defects or small size (if it falls through a 75 mm ring). Subsequently, 400 pears per farm were selected and packed into standard multi-layer telescopic cartons 12.5 kg M12 T (MK6) (dimensions: 300 × 400 × 220 mm; internal trays: 383 × 281 mm and a liner bag: length 410 mm; width 310 mm and depth 775 mm) based on industry practice.

Supply Chains Simulated
From each farm, 100 pears were used for each supply chain scenario simulated i.e., 200 pears per scenario. From each farm, 100 bunches were used for each supply chain scenario simulated, i.e., 200 bunches per scenario. Four supply chain scenarios were studied (Table 1), representing the range of postharvest handling practices that occur in local and export marketing of pears in the South African fresh fruit industry. According to export pear producers (pers. communication Amelia Vorster, Technical Advisor (Quality)-Karsten Western Cape), scenario D is a common occurrence and leads to tension between role-players as to whether the fruit was mishandled before the report was written and who is responsible for the losses if it is higher than expected.

Postharvest Losses
The base measurement for losses at harvest occurred in the orchards. Ten full 20 L picking bags were selected at each farm, and the contents were carefully inspected to quantify the percentage of fruit that would be discarded due to defects or small size (if it falls through a 75 mm ring). At each evaluation time thereafter, physical losses were quantified as the decrease in fruit weight expressed as the percentage of fresh weight loss from harvest, and the amount of fruit lost due to decay, expressed as the percentage of fruit with the disorder. Table 1. Description of the supply chain scenarios studied.

Supply Chain Scenario Description Environmental Condition
A Pears were harvested and stored under ambient conditions, typical in areas that lack cold storage facilities.
Measurements were taken at harvest and after 3, 7, and 10 days.
Under ambient conditions for 10 days: 25

Quality Attributes
The following attributes were measured at each evaluation time:

Weight loss
For weight loss, 30 pears from two farms were selected, which gave 60 pear samples per supply chain scenario. Weight loss was expressed as a percentage of the initial fruit weight.

2.
Total soluble solids (TSS) concentration Fruit juice was extracted using a juice extractor (Mellerware-600 W Liqua Fresh Juice Extractor, South Africa). TSS of juice was measured with a digital refractometer (Atago, Tokyo, Japan). For the total soluble solids (TSS) concentration, samples of 18 pears per supply chain were used.

3.
Titratable acidity (TA) TA of juice was determined by titration to pH 8.2 using a Metrohm 862 compact titrosampler (Herisau, Switzerland). For TA, samples of 18 pears per supply chain were used.

4.
Peel color Color was assessed using a colorimeter (Minolta CR-400, Minolta Corp, Osaka, Japan) and expressed as CIE L*, a*, b* coordinate where L* defines lightness, a* denotes the red/green value and b* the yellow/blue value [25]. Eighteen pears per supply chain scenario were evaluated for peel color.

Firmness
Pear firmness (N) was measured using a penetrometer fitted with an 8 mm diameter probe [13,26] (Güss Manufacturing, Strand, South Africa). Measurements were made on the widest part of the fruit after a 1-2 cm diameter area of peel was removed from the area to be tested using a vegetable peeler. Eighteen pears per supply chain scenario were evaluated for firmness.

6.
Ethylene production Ethylene production was measured as described by [27,28]. Nine pears were weighed with an accuracy of up to 1 g and sealed, three per chamber, in 3200 mL air-tight glass chambers for 1 h at ambient conditions (25.1 ± 1.3 • C, 46.6 ± 6.0% RH). The concentration of ethylene in the container was then measured using an ICA 56 ethylene meter (International Controlled Atmosphere Ltd. Instrument Division UK) with an accuracy of up to 0.1 ppm, within a time of 15 s, at a flow of 0.8 L min −1 . Based on the results and having measured the specific gravity of the pears as 1.06, ethylene production per 1 kg of fruit per hour was calculated. The ethylene production rate was measured in ppm and expressed as C 2 H 4 µL·kg·h.

7.
Respiration rates Respiration rate was measured as described by [29] with slight adaptations. Nine pears were weighed with an accuracy of up to 1 g and transferred to 3200 mL air-tight glass chambers, three per chamber, for 1 h at ambient conditions (25.1 ± 1.3 • C, 46.6 ± 6.0% RH). The CO 2 and O 2 concentrations were then measured using a combined CO 2 /O 2 analyzer (CheckMate 9900, PBI-Dansensor, Denmark) with a syringe through a rubber septum attached to the top of the 3200 mL chambers. The following equation was used to calculate the CO 2 concentrations: where RCO 2 is the respiration rate expressed in CO 2 mL·kg·h, CO 2i is the initial concentration of CO 2 in the chamber at the beginning of the experiment, CO 2f is the concentration of CO 2 at time t, W is fresh weight, and Vf is free volume.

Environmental and Economic Impacts of Postharvest Losses
Total greenhouse gas emissions were calculated using values provided by [30]. That study examined the annual cycle for pear production, beginning with establishment costs, raw material extraction for the production of inputs used on the orchard and included the factors of fertilizer, tillage, irrigation, pest management, electricity, and fuel consumption, ending at the delivery of pears. For every ton of pears produced, stored, and transported to the retail market approximately 0.25 ton of CO 2 eq is emitted into the atmosphere. The energy cost for producing and marketing the lost produce was obtained using a reference value of 3703 MJ/ton provided by [31], and the water footprint was determined by multiplying the quantity of lost produce with the reference water footprint value of pears at 920 m 3 /ton provided by [32]. The value of pears lost was calculated using values provided by [14] R5871/ton for locally sold produce, and R11366/ton for exported produce.

Statistical Analysis
Data on farm fruit losses at harvest were subjected to a one-way analysis of variance (ANOVA) and the physicochemical analysis data (weight loss, peel color, firmness, total soluble solids (TSS), titratable acidity (TA), respiration rate, and ethylene production) were subjected to mixed model analysis of variance (ANOVA) using Statistica version 13.2 (TIBCO Software Inc., Palo Alto, CA, USA) with 'farm' and 'time' as fixed effect and cartons as a random effect.

Physical Losses at Farm Level
The measured loss of pears at harvest for individual farms was 18% and 19%, respectively. The average loss at harvest on the farm level was 18%. Of the 18% lost at harvest on the first farm, the main reasons were due to deformed fruit (50%), small size (48%), and chafed peel (2%) on the first farm, while on the second farm, the main reasons were the same, but the proportions differed: the majority of the losses were due to small size (80%), chafed peel (18%) and deformities (2%). The average values for both farms together were small size (65%), deformity (26%), and chafed peel (9%).

Weight Loss and Decay Supply Chain Scenario A (Handling and Marketing Fruit under Ambient Conditions)
There was no statistically significant difference in fruit weight up to 10 days after harvest (p = 0.42), as shown in Table 2. However, there was a 2.2% decrease in weight, which would affect the profit margin, as fruit is sold by weight. While not statistically significant, this decrease in weight is important in terms of losses as it could affect the profit margin. No decay was present for up to 7 days when 3.3% of the fruit showed visible signs of decay, increasing to 6.6% after 10 days.

Supply Chain Scenario C (to International Retail Markets)
There was no statistically significant difference in weight after storage or during a shelf life of 10 days (p = 0.93). However, weight decreased by 1.49% after 28 days in cold storage, 1.77% after 10 days in retail conditions, and 2.24%, 2.97%, and 3.60% after 3, 7, and 10 days under ambient conditions, respectively (Table 4). No decay was present during the course of the measurements. There was no statistically significant difference in fruit weight over time (p = 0.94), although a 0.98% decrease in weight is noted after 28 days in cold storage, 1.36% after two days at 'abusive' ambient conditions, 2.09% after 10 days in retail conditions, and 2.91%, 3.26%, and 3.71% after 3, 7, and 10 days under ambient conditions, respectively. (Table 5). No decay was present during the measurements.

Supply Chain Scenario A (Marketing at Ambient Conditions)
Pear color became lighter (L) over time (Table 6), and the change was statistically significant (p < 0.01). The measurements for a* (p < 0.01) denoting the red/green values and b* (p < 0.01), indicating the yellow/blue values, also changed significantly, indicating that the fruit became less green and more yellow over time. There were also significant differences in firmness; the values decreased with time as the fruit became softer as they ripened from 89.83 N at harvest to 71.29 N after 7 days and down to 4.71 N after 20 days (p < 0.01). Although the TSS values increased over time, the increase was not statistically significant (p = 0.45). The TA values also did not change significantly for the duration of the trial (p = 0.15). Respiration dropped to its lowest after 7 days and then rose again to peak at 17 days (p = 0.02), while Ethylene levels remained quite low for the first 7 days and then increased significantly from 14 days to 20 days after harvest (p < 0.01). Table 6. Supply chain scenario A: Changes in quality attributes of color (L*, a* and b*), firmness (N), TSS (Brix • ), TA (%), respiration rate (CO 2 mL·kg·h) and ethylene production (C 2 H 4 µL·kg·h) of 'Packham's Triumph' pears at harvest and after 3, 7, and 10 days at ambient conditions (25.1 ± 1.3 • C and 46.6 ± 6.0% RH).

Supply Chain Scenario B (to Local Retail Markets)
Pear color (L) indicates that the lightness of the fruit did not change significantly (Table 7) during the time measurements were taken (p = 0.25). The measurements for a* denoting the red/green values indicate that the pears retained their harvest color during the two weeks in cold storage, after 10 days in retail conditions, and after 10 days at ambient conditions. However, they became significantly (p < 0.01) less green. The b* values, indicating the yellow/blue color component changed significantly (p < 0.01) and showed that the fruit became yellower during the initial two weeks in -0.5 • C cold storage and continued the trend during their shelf-life period. Firmness decreased from 89.83 N to 79.53 N during cold storage and retail conditions when removed to ambient conditions; however, the firmness decreased rapidly to 37.66 N after 3 days, 20.10 N after 7 days, and 10.2 N after 10 days. The TSS (p = 0.38) values did not change significantly during the duration of the trial. The TA values also did not change significantly (p = 0.80). The respiration rate dropped during cold storage, although it was not significantly different from that at harvest. At ambient conditions, the respiration rate increased significantly (p < 0.01), peaking at 7 days. Ethylene levels remained low from harvest through storage at both cold-room and retail conditions and then increased significantly (p < 0.01) and quickly from 7 to10 days at ambient conditions.

Supply Chain Scenario C (to International Retail Markets)
Pear color (L*), indicating lightness, darkened slightly, yet significantly (p = 0.02), during cold storage and became lighter again with increases in temperature and relative humidity ( Table 8). The measurements for a* (p < 0.01) denoting the red/green values indicate that the pears retained their harvest color during the four weeks in cold storage and during the 10 days at retail conditions, becoming significantly less green under ambient conditions. The b* values, indicating the yellow/blue color component, also changed significantly (p < 0.01), indicating that the pears became considerably yellower during the four weeks in −0.5 • C cold storage, after which they stayed the same until exposed to ambient conditions when they yellowed further. Firmness decreased from 89.83 N to 78.65 N during four weeks in cold storage and did not significantly change during the 10 days in retail conditions. However, when moved to ambient conditions, the firmness decreased rapidly to 23.93 N after 3 days, 12.06 N after 7 days, and 9.41 N after 10 days. The TSS (p = 0.12) and TA (p = 0.20) values did not change significantly during the duration of the trial. The respiration rate dropped right down to no discernible activity during the four weeks in cold storage and was significantly different from that at harvest, and then picked up slightly during storage in retail conditions, and significantly when placed in ambient conditions where the respiration rate peaked at 7 days. Ethylene levels remained low after harvest and cold storage of 28 days. While it increased during retail conditions, it was not statistically significant until moved to ambient conditions when it increased significantly (p < 0.01) and quickly during its 3 to 10 days shelf-life. Table 7. Supply chain scenario B: Changes in quality attributes of color (L, a* and b*), firmness (N), TSS (Brix • ), TA (%), respiration rate (CO 2 mL·kg·h), and ethylene production (C 2 H 4 µL·kg·h) of 'Packham's Triumph' pears at harvest, after 14 days cold storage (−0.3 ± 0.7 • C, 81.3 ± 4.1% RH), after another 10 days in retail conditions (5.4 ± 0.6 • C, 83.7 ± 2.9% RH) and then 3, 7, and 10 days at ambient conditions (25.1 ± 1.3 • C and 46.6 ± 6.0% RH).

Supply Chain Scenario D (Simulated 'Abusive' Treatment of Fruit within the Export Chain)
Pear color (L*), darkened slightly, yet significantly, during cold storage (Table 9) and became lighter again with increases in temperature and relative humidity. The measurements for a* (p < 0.01) denoting the red/green values indicate that the pears retained their green harvest color during the four weeks in cold storage. No significant change occurred during the 2 days in ambient conditions or when placed in retail conditions for 10 days, but they did become significantly less green after 3, 7, and 10 days' shelf-life in ambient conditions. Table 9. Supply chain scenario D: Changes in quality attributes of color (L*, a* and b*), firmness (N), TSS (Brix • ), TA (%), respiration rate (CO 2 mL·kg·h), and ethylene production (C 2 H 4 µL·kg·h) of 'Packham's Triumph' pears at harvest, after 28 days cold storage (−0.3 ± 0.7 • C, 81.3 ± 4.1% RH), after 2 days 'abusive' temperature and humidity (25.1 ± 1.3 • C and 46.6 ± 6.0% RH), after another 10 days at retail conditions (5.4 ± 0.6 • C, 83.7 ± 2.9% RH) and then 3, 7, and 10 days at ambient conditions (25.1 ± 1.3 • C and 46.6 ± 6.0% RH). The b* values, indicating the yellow/blue color component also changed significantly (p < 0.01), meaning that the fruit became considerably yellower during the four weeks in −0.5 • C cold storage after which it did not change significantly, although the values show a trend of becoming more yellow under ambient shelf-life conditions. After four weeks in cold storage, firmness decreased by around 9.81 N, from 90.12 N to 81.49 N, and remained at that firmness during the 2 days in ambient conditions. During the 10 days in retail conditions, however, the firmness dropped with another 19.61 N to 62.47 N, and when moved to ambient conditions, the firmness decreased rapidly to below 19.12 N firmness. There were no significant differences in TSS (p = 0.45) or TA (p = 0.51) during the whole supply chain. Fruit respiration rate dropped right down to no measurable activity during the four weeks in cold storage. After 2 days at ambient conditions, the respiration rate was again similar to that at harvest, dropping once more during the 10 days under retail conditions, but not significantly different from harvest or ambient conditions. During the 3-, 7-and 10-days shelf-life measurements, the respiration rate peaked after 3 days, although it was not significantly different between 3, 7, and 10 days in ambient conditions. Ethylene levels remained low and statistically the same after harvest, cold storage of 28 days, 2 days in ambient, and 10 days in retail conditions. When moved to ambient conditions again, it increased significantly (p < 0.01) and quickly during its 3 to10 days shelf-life.

Socio-Economic Impacts of Postharvest Losses
Based on the percentage losses along the simulated supply chains, estimates were made to determine the volume of pears that could be lost at the national level (Table 10). In 2018, South Africa produced approximately 406,644 tons, of which 49,926 tons were sold locally and 212,149 tons were exported [14]. The 18% loss measured at harvest translated to an estimated 73,196 tons at the national level with a value of R 429,733,716 (USD 28,445,436) if they were sold on the local market and R 831,945,736 (USD 55,069,125) if they could have been exported. In addition, 271,044,788 MJ of energy has been lost, 67,340,320 m 3 of water, and 18,299 tons of CO 2 eq has been released into the atmosphere. Table 10. Impact of postharvest losses in terms of magnitude, monetary value, energy used, water footprint and greenhouse gas emissions in the production and distribution of pears along different supply chains. * Estimated values obtained using the volume of pears sold locally, 49,926 t and exported, 212,149 t [14].

Physical Losses at Farm Level
Losses begin on the farm even before a product moves into the supply chain. The most common source of such losses is financial reasons which influence producers' willingness to bring their product to market. Minimum quality standards for fresh produce set by governments, large harvests that reduce commodity prices, and consumer demand for blemish-free produce, for example, often result in the removal of small, misshapen, or otherwise blemished produce [33].
The measured loss at harvest of 18% was almost double the 10% reported by [34], measured in a study on food loss in primary production of the Nordic countries of Denmark, Finland, Sweden, and Norway. As well as findings by [35] who measured losses of 8% for Packham's Triumph pears in Hungary. Similarly, losses of 5% were reported by [36]; however, that study collected no primary data for pears, and study estimates were based on 'expert judgment'. While [37] reported that postharvest losses of pears in India were in the range of 20-30%, this was due to inadequate facilities and improper handling, packaging, and storage techniques.

Supply Chain Scenario B (to Local Retail Markets)
The changes in color correlate with the results published by [49] for cv. 'Packham's Triumph'. The initial decrease in firmness during two weeks of cold storage corresponds to findings of [49] reporting on cv. 'Packham's Triumph'. However, after 5 days at room temperature (24 ± 1 • C) in that study, the firmness only decreased to around 60 N, from a starting firmness of 75 N, which is much firmer than reported in this study. The results for TSS values were similar to findings by [15] for cv. 'Packham's Triumph': no significant differences in TSS between harvest and 4 or 8 months of storage were found, although differences were found after 2, 6, and 10 months in that study. The TA similarly correlates with results of [15] where no significant differences were found during the first season whereas differences were found in the second season, but only in one treatment of 6 months storage and 7 days shelf-life conditions. In addition, [43] reported no significant difference in TA levels for cv. 'Red Clapp's' after 15 days at −0.5 • C and 7 days at 20 • C. Results for respiration rate were similar to findings for cv. 'Conference' published by [50] reported that the respiration rate increased after removal from storage with a decrease at the end of the shelf-life period.

Supply Chain Scenario C (to Export Retail Markets)
These results are similar to those reported by [49] for the same cultivar, Packham's Triumph, grown in Brazil. With regard to firmness, results were similar to those reported by [49]: a 10 N drop in firmness during cold storage of 15 days and a rapid decline in firmness during the simulated shelf-life period. Similarly, [51] also reported a remarkable decrease in fruit firmness of 'Packham's Triumph' after 5 days under ambient conditions subsequent to being stored under regular cold storage (0 • C, 90-95% RH), although it is not reported what the firmness was after cold storage but prior to the 5 days of shelf life. Findings on TSS and TA were similar to findings by [15,51], while [49] reported significant increases in TSS and a decrease in TA during cold storage. Respiration rates confirm reports of [47,52,53] stating that lower temperature drastically slows respiration rate. Ethylene production levels were similar to those reported by [50], with an increase in ethylene production after 4 days shelf life subsequent to cold storage of either 6 or 8 weeks, for cv. 'Conference'.

Supply Chain Scenario D (Simulated 'Abusive' Treatment of Fruit within the Export Chain)
The results were similar to those described for supply chain scenario C, with the main difference being a faster increase in respiration rate and ethylene production.

Socio-Economic Impacts of Postharvest Losses
The socio-economic impacts of these losses, from harvest to shelf life, indicate a financial loss of between R 492 million to over R831 million annually for the South African pear industry.
Additionally, as much as 301 million MJ of fossil energy and 69 million m 3 of fresh water resources were lost. At the Eskom tariff rate of R0.90 per kWh, the lost energy is worth R75.25 million [54]. The fresh water lost could sustain 3,7 million individuals daily for a whole year at a daily minimum usage rate of 0.05 m 3 per day [55], while it will require planting 0.5 million trees to sink the 19,690 tons GHG emissions of the pear losses (0.039 metric ton per urban tree planted) [56].

Conclusions
The results of this research reveal that postharvest losses of pears, from harvest along the supply chain to retail level and shelf life (consumer storage), have a serious impact on food security, profitability, and the sustainable management of natural resources. Worldwide interest in the food loss and the waste problem has soared; however, losses that occur at farm level are often overlooked. In this study, the greatest loss measured along the supply chain, 18%, was at harvest. As the majority of losses were due to small size and not any deformity or mechanical damage, industry size standards could be part of the problem. With a shift in perception, smaller fruit could also be sold as fresh fruit and not downgraded for juicing. Smaller fruit is also known to be sweeter and sweeter fruit tends to be more popular. One example is a line of child-sized pears centered on flavor that could transform the way consumers view small pears.
In addition, fruit losses in quantity and quality under ambient conditions (25.1 ± 1.3 • C; 46.6 ± 6.0% RH) were much higher than under refrigeration. While the retail simulation in this study was done at 5 • C, many retailers exhibit fruit on open shelves where the temperature is much higher, essentially in ambient conditions that can reach up to 26.68 ± 0.92 • C and 59.79 ± 4.86% RH. This shortens the shelf life significantly and increases the amount of fruit lost due to decay.
Despite the huge lack of data in existing knowledge of global food loss and waste, the largest gap in knowledge presents the lack of available data on postharvest losses; data on food waste was at the retail, household level and shelf life. Therefore, the present study aimed to contribute to the advancement of new knowledge by generating primary data on the quantity and postharvest quality losses along the pear supply chain to better manage the food loss and waste problem. However, more studies are needed to gain information and insights on the handling procedures and origin of defects associated with losses for the supply chains of every product.