Investigating bruise susceptibility of pomegranate cultivars during postharvest handling

Bruising is the most common type of mechanical damage of horticultural produce which results mainly from excessive impact and compression forces due to improper postharvest handling. The presence of bruise contributes to downgrading and rejection of produce, thereby contributing to postharvest losses; it is therefore important to understand the mechanism of bruising and how to reduce it. This study investigated the susceptibility of three pomegranate (Punica granatum L) fruit cultivars (‘Acco’, ‘Herskawitz’ and ‘Wonderful’) to bruising by impacting a known mass of steel ball onto individual fruit. Impact threshold level required to cause bruising was investigated by subjecting fruit to damage at different drop heights (5, 10, 15, 20 and 25 cm) which corresponded to low impact energy levels. Bruise size (area and volume) and bruise susceptibility (bruise volume per unit of impact energy) at higher drop heights (20, 40 and 60 cm) were cultivar dependent in the order of ‘Wonderful’>‘Herskawitz’> ‘Acco’. Similarly, the drop height (cm) at which bruising was first observed and the associated bruising incidence (%) ranged from 5 cm and 34% for ‘Wonderful’, to 10 cm and 21% ‘Herskawitz’ and 15 cm and 27% for ‘Acco’. ‘Wonderful’ pomegranate fruit had the lowest equivalent drop height (3.13 cm) at which bruising occurred, which indicates its higher susceptibility to bruising compared with the other cultivars studied. The findings reported in this study provide science-based tools to assist in improving postharvest handling management of fresh pomegranate fruit to minimize the incidence of mechanical damage. In addition, the methodology can be applied to assess the bruise damage susceptibility of other types of fresh produce as part of overall management strategy to reduce the high incidence of postharvest losses of agricultural and horticultural commodities.