Quantity and quality losses of 'Crimson Seedless' grape and 'Packham's Triumph' pear along the supply chain and associated impacts

Thesis (PhDAgric)--Stellenbosch University, 2022.

ENGLISH ABSTRACT: Postharvest loss and waste (often referred to as wastage) is a global problem affecting all produce along the supply chain from farm to plate. These losses not only decrease food supply but also mean that huge amounts of the resources and effort used in the production of horticultural crops are squandered. From an economic perspective, addressing postharvest losses is not only helpful to producers aiming to sell more, but also to consumers who could save money as the available food becomes more affordable. To date, there is little scientific data available on the incidence and magnitude of postharvest losses of fruit and other food crops in South Africa. The aims of this study were to assess postharvest losses in quantity and quality of ‘Crimson Seedless’ table grape and ‘Packham’s Triumph’ pear along the supply chain and quantify the associated economic, environmental and resource impacts in order to inform mitigating actions. The base measurement for table grape losses occurred in the packhouses of four farms in the Western Cape during the commercial harvest. The highest quantity (%) of physical losses in the supply chain was found to occur at this level when compared to the cold storage (2 or 4 weeks at -0.3°C ± 0.7°C and 81.3% ± 4.1% RH), retail (10 days at 5.4°C ± 0.6°C and 83.7% ± 2.9% RH) and consumer/home (ambient) storage (25.1 ± 1.3°C and 46.6 ± 6.0% RH) stages. There were large differences between the 2017 and 2018 seasons, with the 2018 season’s losses being half that of the first. The main reason for losses at the packhouse level was mechanical damage (7.1% in 2017 and 3.09% in 2018) due to rough handling of crates and could be improved by making workers more aware of the necessity to handle crates with care. Harvest timing is also essential, as delayed harvesting reduces shelf life and increases postharvest losses, as evidenced by this research. The farm that sustained the highest losses in 2017 (23.3%) harvested later than was optimal, and therefore, the bunches stayed on the vines too long. In 2018 the harvest occurred two weeks earlier than in 2017, and the grapes were in better condition leading to fewer losses on farm level (5.85%). Among all supply chain scenarios, the main quality problem was rachis and stem browning at temperatures higher than -0.5ºC. This caused berries to drop faster and bunches to look less fresh, as well as causing bunches to weigh less when sold. While 500 g and 1 kg punnets are routinely kept at around 5ºC at the retail level, during peak season 4.5–10 kg cartons are often stacked on the floor under ambient conditions. Therefore, the table grapes would have a maximum shelf life of seven days before the stems have browned and too many berries per bunch are decayed to sell. Therefore, it is advisable to keep cartons at -0.5ºC and high RH and only place bunches in punnets in 5ºC display fridges as the stock sells. The base measurement for losses of pear occurred in the orchard of two farms in the Western Cape during commercial harvest. It was found that 18% of the harvest on the one farm and 19% of the harvest on the other, did not reach the minimum quality standards. The main reasons were deformed fruit and too small size. The only decay, among all supply chain scenarios, occurred when pears were kept under ambient conditions (25.1 ± 1.3°C, 46.6 ± 6.0% RH) where 3.3% were decayed after seven days and 6.6% after 10 days. The majority of physical losses were due to weight loss with a 3.9%, 3.6 and 3.7% decrease in weight for supply chain Scenario B (to local retail markets), supply chain Scenario C (to export retail markets) and supply chain Scenario D (simulated ‘abusive’ treatment of fruit within the export chain) respectively. . Of the data gaps in the existing knowledge on global food loss and waste, the largest gap is the lack of available data on postharvest losses, retail and household level (shelf-life) food waste data. Therefore, this study contributed to the advancement of new knowledge by generating primary data on postharvest quantity and quality losses along the supply chain to manage the food loss and waste problem better.

AFRIKAANSE OPSOMMING: Na-oes verliese en vermorsing is 'n wêreldwye probleem wat alle produkte in die voorsieningskettings van plaas tot bord beïnvloed. Hierdie verliese verminder nie net die voedselvoorraad nie, maar beteken ook dat groot hoeveelhede van die hulpbronne en moeite wat in die produksie van tuinbougewasse gebruik word, vermors word. Vanuit 'n ekonomiese oogpunt is die vermindering van na-oesverliese nie net nuttig vir produsente wat meer wil verkoop nie, maar ook vir verbruikers wat geld kan bespaar namate die beskikbare voedsel meer bekostigbaar word. Tot op hede is daar min wetenskaplike data beskikbaar oor die voorkoms en omvang van na-oesverliese van vrugte en ander voedselgewasse in Suid-Afrika. Die doel van hierdie studie was om na-oes verliese in hoeveelheid en kwaliteit van druiwe 'Crimson Seedless' en pere 'Packham's Triumph' deur die verskaffingsketting te meet en die gepaardgaande ekonomiese, omgewings- en hulpbronimpakte te bereken om ingeligte besluite te kan maak wat na-oesverliese verminder. Die basismeting vir tafeldruifverliese het tydens die kommersiële oes in die pakhuise van vier plase in die Wes -Kaap plaasgevind. Die grootste hoeveelheid (%) fisiese verliese in die voorsieningsketting het op hierdie stadium voorgekom in vergelyking met die verkoelde opberging (2 of 4 weke by -0.3°C ± 0.7°C en 81.3% ± 4.1% RH), kleinhandel (10 dae by 5.4°C ± 0.6°C en 83.7% ± 2.9% RH) en verbruiker (25.1 ± 1.3°C en 46.6 ± 6.0% RH) stadiums. Daar was groot verskille tussen die 2017- en 2018- seisoene met 2018 se verliese die helfte van die gedurende die 2017-seisoen. Die hoofrede vir verliese op pakhuisvlak was meganiese skade (7.1% in 2017 en 3.09% in 2018) as gevolg van rowwe hantering van kratte en kan verbeter word deur werkers meer bewus te maak van die noodsaaklikheid om kratte versigtig te hanteer. Oestydsberekening is ook noodsaaklik, aangesien vertraagde oes raklewe verminder en lei tot verhoogde na-oes verlies soos bewys deur hierdie navorsing. Die plaas wat die hoogste verliese in 2017 gely het (23.3%) het later as optimaal geoes en die trosse het dus te lank aan die stokke gebly. In 2018 het die oes twee weke vroeër as in 2017 plaasgevind, en die druiwe was in 'n beter toestand wat gelei het tot minder verliese op plaasvlak (5.85%). Die belangrikste kwaliteitsprobleem was rachis en stingel verbruining by temperature hoër as -0,5ºC. Dit het veroorsaak dat bessies vinniger val en dat trosse minder vars lyk, asook dat trosse minder weeg as hulle verkoop word. Terwyl 500 g of 1 kg plastiek bakkies gereeld by ongeveer 5ºC op kleinhandelvlak gehou word, word 4,5 –10 kg kartonne dikwels op die vloer gestapel tydens piek seisoen by kamer temperatuur en humiditeit. Die tafeldruiwe sou dus 'n maksimum rakleeftyd van sewe dae hê voordat die stingels verbruin en te veel bessies per tros vrot om te verkoop. Dit word dus aanbeveel dat kartonne by -0,5ºC en hoë RH gehou word en trosse slegs in bakkies in 5ºC yskaste geplaas word soos die voorraad verkoop. Die basismeting vir verliese van pere het tydens die kommersiële oes in die boord van twee plase in die Wes-Kaap plaasgevind. Daar is gevind dat 18% van die oes op die een plaas en 19% van die oes op die ander plaas nie die minimum kwaliteitstandaarde bereik het nie. Die hoofredes was misvormde en te klein vrugte. Die enigste bederf, onder alle voorsieningskettingscenario's, het plaasgevind toe pere by kamer- temperatuur en humiditeit (25.1 ± 1.3°C, 46.6 ± 6.0% RH) gestoor is waar 3.3% na 7 dae en 6.6% na 10 dae bederf het. Die meerderheid fisiese verliese was as gevolg van gewigsverlies met 'n 3.9%, 3.6 en 3.7% afname in gewig vir voorsieningsketting Scenario B (na plaaslike kleinhandelmarkte), voorsieningsketting Scenario C (om kleinhandelmarkte uit te voer) en voorsieningsketting Scenario D (gesimuleerde swak hantering van vrugte in die uitvoerketting) onderskeidelik. Die grootste gaping in die bestaande kennis oor wêreldwye voedselverliese en vermorsing, is die gebrek aan beskikbare data oor na-oesverliese, kleinhandel- en huishoudelike vlak (rakleeftyd). Hierdie studie het dus ten doel gehad om nuwe kennis by te dra deur primêre data oor na-oesvelies hoeveelheid en kwaliteitverliese in die voorsieningsketting te genereer om sodoende die voedselverlies- en afvalprobleem beter te bestuur.

Doctoral