Plasticized Starch-Based Coatings To Improve Strawberry (<i>Fragaria</i>×<i>Ananassa</i>) Quality and Stability

Abstract

Starch-based coatings were applied to extend storage life of strawberries (Fragaria × ananassa) stored at 0 °C and 84.8% relative humidity. The effects of amylose content of the starch, the type of plasticizer (glycerol and sorbitol), and the inclusion of antimicrobial agents on coating formulation were analyzed. Microstructure characterization of coatings was related to water vapor permeability (WVP) observations. Coatings made with starches with the higher amylose content decreased WVP and weight losses and retained fruit firmness for longer periods than coatings formulated with medium amylose content starches. Coatings with sorbitol showed lower WVPs than glycerol ones. Both sorbitol and glycerol reduced weight losses and maintained texture and surface color of fruits, with 20 g/L sorbitol being the most effective plasticizer option. Modifications of physiological parameters in strawberries such as anthocyanin content, reducing and nonreducing sugars, titratable acidity, and pH were slowed for coated fruits. The formulations with potassium sorbate reduced microbial counts, extending strawberry storage life from 14 days (for control fruits) to 28 days in coated strawberries. The addition of citric acid enhanced antimicrobial action of potassium sorbate. Keywords: Starch coating; plasticizer; strawberry; water vapor permeability; refrigerated storage