Freshness maintenance of blueberries (vaccinium corymbosum L.) during postharvest using ozone in aqueous phase: Microbiological, structure, and mechanical issues

Abstract

The effect of aqueous ozone at different doses on fungal incidence, microstructure, mechanical properties, and weight loss of blueberry fruit (Vaccinium corymbosum, cv. O’Neal) throughout 20 days of storage at 4 ± 1 °C was studied. Fruits were exposed to 10 and 18 mg O3 L-1 in a bubble column for different periods of time ranging from 10 to 30 min. Native mycobiota and Botrytis cinerea incidences were reduced by ozone exposure. After 15 days of storage, exposure to 18 mg O3 L-1 for 10 and 20 min reduced the percentage of infected fruit in ~ 34 and 40 %, respectively, when compared with untreated blueberries. Slight but no significant differences among ozone treatments were observed for native mycobiota and B. cinerea incidence. Stiffness, rupture force, and mechanical work required to break the fruit epidermis were not significantly affected by ozone treatments. The effect of ozone treatment on weight loss of blueberries was dose-dependent and was partially correlated with microstructural changes induced by ozone: disruptions in outer tangential and epidermal cell walls and alteration of the cuticle. Exposure times beyond 15 min significantly increased weight loss and did not achieve greater fungal inhibition with respect to 10- and 15-min ozonized fruit. Thus, the ozone dose to be selected would be limited by the negative effect on weight loss. Exposure to 18 mg O3 L-1 for 10 min would be the most suitable treatment to reduce fungal decay without causing an excessive loss of weight along cold storage.