Quantifying postharvest losses of 'Crimson Seedless' table grapes along the supply chain

High incidence of postharvest losses is a major challenge to global food security. Addressing postharvest losses is a better strategy to increase business efficiency and improve food security rather than simply investing more resources to increase production. The lack of primary data on postharvest losses at critical steps in the fruit value chain and the unknown economic, environmental and resource impacts of these losses currently make it difficult to formulate mitigation strategies. This paper quantifies postharvest losses and quality attributes of 'Crimson Seedless' table grapes at farm/packhouse and retail levels. In addition, factors influencing the incidence of losses were investigated to provide a basis for the development of waste mitigation measures. Table grapes were sampled from four farms in the Western Cape Province of South Africa, the largest deciduous fruit production and export region of Southern Africa. Results showed that losses immediately after harvest at the four farms ranged from 8 to 23%. The main reasons for losses were mechanical damage (7.1%), inadequate berry colour (too green, 5%) and decay (1.8%). After packaging, maintaining cold storage (-0.3±0.7°C, 81.3±4.1% RH) was effective in maintaining berry quality up to 14 d during cold storage. Incidence of decay, stem browning and SO₂ damage occurred when grapes were transferred to retail fridge storage (5.4±0.6°C, 83.7±2.9% RH) and ambient conditions (25.1±1.3°C, 46.6±6.0 RH).