Development of novel postharvest techniques for the preservation of blueberry fruit

Over the past decade, the blueberry industry both in South Africa and around the world has shown extensive growth. Blueberry fruit have become a valuable agricultural commodity, due to its high levels of anti-oxidants and other health benefits. The average storage life of blueberries is estimated to be between 35 and 40 days, where postharvest fungal infections are the greatest limiting factor for longer storage. Blueberry fruit are susceptible to various pathogen infections, both pre- and postharvest, with grey mould (Botrytis cinerea) being the most common. Sulphur dioxide (SO2) generating pads are a popular postharvest treatment preventing fungal development in table grapes and may have potential for enhancing blueberry storage as well. The aim of this study was to determine whether the SO2 generating pads could effectively prevent postharvest decay development in blueberries. The study was conducted during the 2016 South African blueberry season, investigating the use of SO2 generating pads in isolation, as well as the use of the pads in combination with controlled atmosphere (CA). A variety of cultivars were treated with SO2 and stored under CA, after which they were assessed specifically for postharvest fungal development. Less decay was observed when berries were treated with SO2 generating pad in combination with CA storage conditions. For this treatment, no bleaching or loss in fruit quality was observed. In addition to these results, PCR quantification of B. cinerea DNA levels showed a three times reduction in DNA level when inoculated blueberries were treated with a SO2 generating pad. This trend is seen for both berries that were artificially inoculated with B. cinerea, and berries with a natural inoculum.