Edible Coatings May Increase Quality and Shelf Life of Strawberries

19 Aug 2015 --- Strawberries are one of the most economically important fruits worldwide but are easily susceptible to bruising and are highly perishable. A new study in the August issue of the Journal of Food Science, published by the Institute of Food Technologists (IFT) found that edible active coatings (EACs) based on pectin, pullulan and chitosan may improve quality and shelf life of strawberries.

Edible coatings protect perishable food products from deterioration and act as a protective cover (Atress, 2010).

Pectin is present in the cell walls of many fruits and vegetables; chitosan is a major component of crustacean shells and exhibits antifungal properties; and pullulan provides extracellular support. A team of researchers from Mexico discovered that EACs incorporated with sodium benzoate and potassium sorbate reduced fruit softening, reduced microbial growth, preserved the color, flavor and texture of strawberries, and increased the shelf life of strawberries from six to 15 days.

Edible active coatings (EACs) based on pectin, pullulan, and chitosan incorporated with sodium benzoate and potassium sorbate were employed to improve the quality and shelf life of strawberries. Fruits were washed, disinfected, coated by dipping, packed, and stored at 4°C for 15 days. Application of EACs reduced (P < 0.05) weight loss and fruit softening and delayed alteration of color (redness) and total soluble solids content. In contrast, pH and titratable acidity were not affected (P > 0.05) throughout storage, and ascorbic acid content was maintained in pectin-EAC coated strawberries. Microbiological analyses showed that application of EACs reduced (P < 0.05) microbial growth (total aerobic counts, molds, and yeasts) on strawberries. Chitosan-EAC coated strawberries presented the best results in microbial growth assays. Sensory quality (color, flavor, texture, and acceptance) improved and decay rate decreased (P < 0.05) in pectin-EAC, pullulan-EAC, and chitosan-EAC coated strawberries. In conclusion, EACs based on polysaccharides improved the physicochemical, microbiological, and sensory characteristics, increasing the shelf life of strawberries from 6 (control) to 15 d (coated fruits).

The researchers note that the present work focuses on improving quality and increasing the shelf life of strawberries using edible coatings based on polysaccharides and antimicrobial agents. The results of this work are applicable to industrial food production and postharvest handling to enhance overall quality and shelf life of strawberries.