The Effect of Plasticizers on Mechanical Properties and Water Vapor Permeability of Gelatin-Based Edible Films Containing Clay Nanoparticles

Mahsa Rezaei,Ali Motamedzadegan

doi:10.4236/wjnse.2015.54019

Abstract

The effects of glycerol and sorbitol as two plasticizers on mechanical properties, water vapor permeability, thermal properties, color and capability of heat sealing of gelatin films (of phytophagous fish, bovine gelatin with high gel-forming ability, and bovine gelatin with low gel-forming ability) containing clay nanoparticles were studied in this research. For this purpose, 6 × 2 × 3 factorial experiments using the completely randomized design and comparison of the means at 95% confidence level (α = 0.05) were performed. Higher concentrations of plasticizers increased percentage elongation to the breaking point. When glycerol concentration was raised to over 20%, flexibility of the layers improved but their water vapor permeability increased. The minimum passage of water vapor was that of fish-skin gelatin films containing clay nanoparticles and 30% sorbitol, and the maximum that of bovine gelatin films with high gel-forming ability which contained nanoparticles but no plasticizers (p 0.05). All samples had heat sealing capability, and fish-skin gelatin films containing clay nanoparticles had better heat sealing capability compared with the other samples so that fish-skin gelatin films containing clay nanoparticles with 25% glycerol and 5% sorbitol had the highest flexibility and tensile strength, and remained attached to where they were heat sealed. Electron microscope images showed that films without plasticizers had uniform surfaces, but that samples containing glycerol at concentrations of over 0.20 g/g gelatin exhibited cavities between gelatin chains and that water vapor permeability in gelatin films containing clay nanoparticles.

Highlights

More than five billion tons of waste from packaging materials is produced annually in the world, 30% of which are plastic compounds
The Nanoclay solution was prepared by mixing clay nanoparticles (5% gelatin by weight/FPH) with 50 ml of water stirred at room temperature for 24 hours, followed by complete homogenization of the solution for 10 minutes using ultrasonic devices
The gelatin/plasticizer solution for making the films was prepared at optimal concentration using the method described below

Summary

Introduction

More than five billion tons of waste from packaging materials is produced annually in the world, 30% of which are plastic compounds. Concern for environmental pollution caused by synthesized plastics has attracted researchers to studying the possibility of using natural biodegradable polymers in the production of packaging materials [1]. Covering fresh oranges and lemons with wax to delay the drying out of their peels was tested in the 12th and 13th centuries in China. These coatings substantially reduce evaporation of water from food materials and prevent exchange of respiratory gases and, thereby, decrease fermentation. Natural polymers are biodegradable in nature and are converted into natural products such as CO2, water, ethane, and biomass during a composting process [2] [3]

Methods

Results

Conclusion