Study on the preparation and use of edible coating of fish scale chitosan and glycerol blended banana pseudostem starch for the preservation of apples, mangoes, and strawberries

Abstract

Agro-industries and the fish processing sector generate large amounts of waste, which may be converted into useful ingredients for preserving fruit. Studies show that starch-based edible film still needs some improvement because it’s brittle and weaker, which might be improved by adding chitosan. The study aimed to investigate the optimal composition of edible film-forming material prepared from banana pseudostem starch and fish-scale chitosan to preserve the selected fruits. In the current study, chitosan and starch were extracted from the waste of Nile tilapia fish scale and Dwarf cavendish banana pseudostem as found to be 29.66 ± 0.46 % and 4.26 ± 0.21 %, respectively. Central composite response surface experimental design combined banana pseudostem starch, chitosan, and glycerol to prepare the edible films. Using the Design-expert program, the ideal film-forming composition with an overall acceptability of 0.968 was identified based on the physico-mechanical characteristics of the created composite edible films. It comprised 15 mL of 1 % banana pseudostem starch, 3.2 mL of 0.5 % chitosan, and 0.6 mL of 30 % glycerol. The persistence of the microbial load on coated and uncoated fruits throughout the storage was also assessed in the study. The microbial and fungal growth was significantly lower (>37 %) in optimal edible film-coated fruits than in the control fruits. After 28 days of storage of fruits at room temperature, the microbial count (in CFU/mL) on the edible coated surfaces of apples, mangoes, and strawberries was found to be 2.04 ± 0.32x103, 2.71 ± 0.29x103, and 2.5 ± 0.51x104, respectively. Also noticed the fungus counts of 1.86 ± 0.48x03 (in apples), 1.09 ± 0.11x104 (in mangoes), and 1.56 ± 0.04x104 (in strawberries) in the studied coated fruits after 28 days of storage. Furthermore, the film-coated fruits had a significantly lower weight loss than uncoated fruits. Thus, the studied banana pseudostem starch-chitosan-glycerol composite edible coating potentially preserves by inhibiting the development of natural microbes when storing apples, mangoes, and strawberries, and it is adequate to extend their shelf life.