Characterization of Protein-Based Edible film: A Study on Thickness, Gelation Time, and Microstructure with the Addition of Polyethylene Glycol

Abstract

A protein-based edible film has the potential to serve as an environmentally friendly alternative to conventional plastics in food packaging. It can extend the shelf life of food products through natural means. The objective of this study was to characterise protein-based edible film with the addition of polyethylene glycol as a plasticiser, with a focus on three main aspects: namely, thickness, gelation time and microstructure. This study employed a completely randomised design comprising three treatments and three replicates. The treatments comprised the utilisation of varying concentrations of polyethylene glycol, designated as P1 (35%), P2 (40%), and P3 (45%). No significant difference (P>0.05) was observed between treatments in terms of thickness value and gelation time. The protein-based edible film exhibited thickness values that ranged from 0.075 to 0.124 mm, indicating compliance with the Japanese Industrial Standard. The gelation time required for the film ranged from 13.67 to 16.33 minutes. The microstructure of the whey-gelatin edible film with a high polyethylene glycol concentration exhibited irregularities on the film surface, characterised by porous areas and small cracks. These irregularities resulted in a weakening of the bond between protein molecules, leading to a looser and less dense microstructure during the drying process, which in turn caused the formation of pores and cracks. The optimal treatment, as determined by this study, is the utilisation of polyethylene glycol at a concentration of 35% with a thickness value of 0.075 mm, a gelation time of 13.67 minutes, and the generation of a more uniform and refined microstructure.