Optimization of process conditions for the development of pectin and glycerol based edible films: Statistical design of experiments

Abstract

Background: Biopolymer based edible films have emerged as potential alternatives for conventional plastics in food packaging industry. The properties such as thickness, water vapour transmission rate (WVTR) and transparency of these films would be significantly influenced by the solution components and concentration and process conditions (pH, temperature and relative humidity of drying).

Results: Control and glycerol blended pectin films were developed as per 2³ (two-level three-factor) factorial design of experiments by varying glycerol fraction (25% and 40% w/w) and solution concentration (3% and 5% w/v). The films made from 5% solution showed good moisture barrier properties. Glycerol addition reduced the moisture barrier capability of the films compared to control pectin films. Statistical analysis suggests that, the solution pH and drying temperature considerably affect film properties while the effect of relative humidity of drying is not evident enough. However, the interaction effect of relative humidity (H) with the pH and temperature appeared significant. Regression models were fitted to the data by considering the main and interaction effects, which were significantly affecting a particular property.

Conclusions: Detailed analysis reveals that for obtaining pectin based films with less thickness, low WVTR and high transparency, the optimal conditions preferred are low pH = 3, high T = 48°C and low to medium humidity of drying (H = 40–50%). The fitted regression models were statistically significant at 90% confidence level, pass Lack-of-fit analysis and are adequate to describe the effects of different factors on the targeted film properties.