Utilization of shellac and gelatin composite film for coating to extend the shelf life of banana

摘要

Shellac and gelatin composite films were used to develop edible surface coatings for the shelf-life extension of banana fruits. The physicochemical properties and film coating efficiency of composite films with different concentrations of gelatin were also evaluated for viscosity, surface tension, pH, work of adhesion and spreading coefficient. The results were indicated that an increase in gelatin contents had an effect on the changes in work of the adhesion and spreading coefficient, and hence the film coating efficiency over a banana skin significantly changed. Among all the concentrations of gelatin, 40% gelatin exhibited the appropriate concentration for application as an edible film coating. Therefore, the composite film based on 60% shellac and 40% gelatin with and without PEG 400 at 5% as the edible coating solution for extending the shelf life of bananas was further investigated. The coating method of the composite film over bananas was prepared using a dipping technique. The temperature of all coated samples was kept stable at 25 degrees C for 30 days. Changes in physicochemical and microbiological properties such as colour, titratable acidity, total soluble sugar, weight loss, firmness and total moulds/yeasts counts were also investigated. Composite films, with and without PEG 400, can be applied as an edible coating for post-harvest fruits, and have beneficial effects on retarding the ripening process. They act as an effectively physical barrier around the fruit resulting in slow decreases in weight loss, softening, amount of acid and sugar and maintaining the quality of post-harvest fruits for more than 30 days, compared with uncoated fruits. Therefore, a composite film based on shellac and gelatin could be utilized and added to the value of fruits and vegetables by prolonging their post-harvest shelf life. (C) 2016 Elsevier Ltd. All rights reserved.