Edible coatings incorporating pomegranate peel extract and biocontrol yeast to reduce Penicillium digitatum postharvest decay of oranges

摘要

This study investigated the potential use of two edible coatings, chitosan (CH) and locust bean gum (LBG), which incorporated chemically characterized water pomegranate peel extract (WPPE) or methanol pomegranate peel extract (MPPE) and the biocontrol agent (BCA)Wickerhamomyces anomalus,to control the growth ofPenicillium digitatumand to reduce the postharvest decay of oranges.CH and LBG including pomegranate peel extracts (PPEs) at different concentrations were testedin vitroagainstP. digitatumto determine their antifungal efficacy; at the same time, the tolerance of viable cells ofW. anomalusto increasing concentrations of WPPE and MPPE extracts was assessed. The potential application of selected bioactive coatings was evaluatedin vivoon oranges, which had been artificially inoculated withP. digitatum, causal agent of green mold decay. CH incorporating MPPE or WPPE at all concentrations was able to inhibitin vitro P. digitatum, while LBG was active only at the highest MPPE or WPPE concentrations.W. anomalusBS91 was slightly inhibited only by MPPE-modified coatings, while no inhibition was observed by WPPE, which was therefore selected for thein vivotrials on oranges artificially inoculated withP. digitatum. The experimental results proved that the addition of 0.361 g dry WPPE/mL, both to CH and LBG coatings, significantly reduced disease incidence (DI) by 49 and 28% respectively, with respect to the relative controls. Besides the combination CH or LBG + WPPE, the addition ofW. anomaluscells to coatings strengthened the antifungal effect with respect to the relative controls, as demonstrated by the significant reduction of DI (up to 95 and 75% respectively). The findings of the study contribute to the valorization of a value-added industrial byproduct and provide a significant advancement in the development of new food protectant formulations, which benefit from the synergistic effect between biocontrol agents and natural bioactive compounds.