Reducing susceptibility of fresh produce to physical damage during postharvest handling: The case of pomegranate fruit

A large percentage of fruit waste in the horticultural industry results from mechanical damage such as bruising. Fruit bruise damage is mostly caused by impact, compression or vibration during handling, packaging and transport. This study investigated the susceptibility of three pomegranate fruit cultivars ‘Acco’, ‘Herskawitz’ and ‘Wonderful’ to impact bruising at varying fruit temperature and drop heights. The first experiment investigated the bruise threshold for each cultivar by subjecting selected pomegranate fruit into three minimal drop heights (10 – 20; 5 cm increments) and evaluated the probability of bruise occurrence (PBO). Study of bruise susceptibility was then carried out by dropping pomegranates stored at 5 and 20 ºC from three drop heights (20, 40 and 60 cm) onto a flat ceramic floor. A linear relationship between drop height and bruise volume (BV), bruise area (BA) and bruise susceptibility (BS) across all cultivars was observed. At 10 cm drop height, ‘Wonderful’ fruit had the highest PBO (0.44) whereas neither ‘Acco’ nor ‘Herskawitz’ were bruised. Lowest bruise threshold (515.38 mJ) was found on ‘Acco’ followed by ‘Herskawitz’ fruit (838 mJ). Low temperature (5 ºC) influenced more bruising whereas higher fruit temperature (20 ºC) reduced the bruise damage of all fruit cultivars. Using Pareto charts, effects of drop height, temperature, cultivar and their interactions on bruising were significant (p < 0.05). Overall, this study showed that both drop and/ or impact energy and fruit temperature affect the bruise damage of pomegranate fruit of the investigated cultivars. This study represents the findings of a pilot research aimed at providing the science-based tools to support handling management of fruit in the South African pomegranate industry.