Starch-based composite coatings modulate cell wall modification and softening in Zaosu pears

Abstract

Pear fruit is susceptible to softening and pulp disintegration leading to a short postharvest storage life. One possible method to alleviate softening is the use of edible coatings. Starch-based coatings and films were blended with cumin essential oil to investigate the film characteristics and the effect of the coating treatments on enzyme activities of Zaosu pears stored at 25 °C for 28 d. The essential oil incorporation enhanced the color, barrier properties and mechanical stability of the starch films. The coating treatment delayed fruit pulp degradation and retarded the activities of pectin methylesterase (PME), polygalacturonase (PG), cellulase (Cx), β-galactosidase (β-Gal), pectinesterase (PE), and polygalacturonase (PMG), during ambient storage for 28 d. The malondialdehyde (MDA) and membrane permeability (MP) activities of the coated fruits were lower compared to the control fruits. The composite coating improved the antioxidant enzymes; peroxidases (POD), phenylalanine ammonia lyase (PAL), superoxide dismutase (SOD), and catalase (CAT) and induced the fruit resistance against softening. The energy content; adenosine triphosphate (ATP) and energy charge (EC) and the activities of succinic dehydrogenase (SDH) and cytochrome c oxidase (CCO) enzymes were significantly higher in the coated fruits. It is viewed that the use of modified sweet potato starch with 0.2–0.4 % (v/v) cumin essential oil could be a useful tool in postharvest storage of fresh produce.