From lab to packhouse: efficacy of gum arabic-based edible coatings for extended postharvest life of exported plums

Edible coatings have shown promise in reducing postharvest losses in horticultural produce, but their technological readiness for stone fruit has not been well studied. In this study, gum arabic-based coatings at 2, 5, and 10% were applied to ‘African Delight™’ plums to investigate their commercial viability in a packhouse. Postharvest quality was evaluated during a simulated export regime of cold storage (-0.5°C for 6 weeks) and subsequent shelf life (20°C for 15 d), with and without HDPE bags. Softening was significantly delayed in coated fruit, with flesh firmness resembling control plums packaged in HDPE bags, suggesting that the coating formulations delayed ripening in the fruit. However, coated fruit without HDPE had significantly higher weight loss and shrivel incidence than control plums packed with HDPE bags. Furthermore, the microbial safety of plums coated with GA 10% and Sta-fresh had lower microbial loads compared to control plums. Additionally, a sensory analysis showed that plums coated with GA 10% scored significantly higher in attributes describing the profile of an unripe to semi-ripe plum compared to control plums. Overall, applying GA 10% at the packhouse level may delay ripening, resulting in extended shelf life without compromising the sensory attributes of the fruit. However, further research is needed to improve the moisture barrier properties of the coating to prevent weight loss and shrivel incidence while keeping commercial viability in mind.