The market of food packaging industry is predicted to be worth $423.27 billion by 2025. Biopolymer based edible and biodegradable food packaging films is gaining more importance recently due to the toxic effects of synthetic polymers on environment and health hazards to humans and other animal life.
The focus of present study is to develop polysaccharide (pectin) and protein (gluten) composite films. Castor oil was used as hydrophobic agent to improve moisture barrier properties. A statistical 22 (two-level two-factor) factorial design of experiments was adopted to develop and study the properties of the films. The percent of gluten (15% &30% w/w) and castor oil (5% & 15% w/w) with respect to the amount of pectin were chosen as the two factors. All the other process parameters such as concentration of film forming solution (5% w/v), pH (=3) of solution, temperature (40 ℃) and relative humidity (60%) of drying, were kept constant based on our previous optimization studies. For comparison, a base level films, pure pectin, pectin and gluten without castor oil films were also developed.
All the films were analyzed for sensory, moisture barrier, mechanical, surface hydrophobicity, morphological and biodegradability properties. All films were thin (~ 0.125±0.004) and transparent (ΔΕ= 11 to 25). Films made from 30% w/w gluten and 15% w/w castor oil showed best moisture barrier, and tensile properties. Addition of castor oil improves the hydrophobicity capacity of the films compared to control pectin and gluten films. The moisture permeability reduced by 2 times and the elongation at break decreased by 5 times compared to control pectin films. The Analysis of variance (ANOVA) studies infer that the effect of amount of castor oil (P<0.05) and the combined effect of amount of castor oil and gluten (p<0.05) is significant on the properties of the films.