Mechanical Strength, Solubility, and Functional Studies of Developed Composite Biopolymeric Film

Abstract

The study evaluated the use of corn, quinoa, and tapioca starches with glycerol to develop biopolymer films. The water binding and oil binding capacities of the starches were determined, and tapioca starch was found to have good film-forming properties and produce transparent films. During the study, starches and glycerol with concentrations of 6% $w/v$ and 3% $w/v$ respectively, were used to develop the biopolymer films. These starches were evaluated for water binding and oil binding, with capacities that ranged from 182.62 to 199.60% and 159.02 to 193.33%, respectively. Quinoa starch presented the highest final viscosity (3584.00 cP), followed by corn starch (3058.00 cP) and tapioca starch (2547.00 cP), which indicate that these starches possess an intermediate range of viscosities required for the development of biopolymeric films. Comparative studies of the properties of starches were done with the intention of developing better quality films among corn, quinoa, and tapioca starch as base raw materials. Tapioca starch exhibits a good film-forming property and produces transparent films. Further, based on the evaluation of physical and mechanical properties, tapioca starch (6% $w/v$ ) with glycerol (3% $w/v$ ) was found suitable as a base ingredient to develop the composite biopolymeric films. Results showed that the functional properties of tapioca starch-based films were significantly enhanced after the incorporation of whey protein isolate (WPI). Particularly, the solubility of different films prepared from tapioca with WPI as the base material was measured at three different temperatures, i.e., 5, 25, and 50°C, and significant differences in solubility at different temperature values were observed. An increase in the tensile strength (TS) after the incorporation of WPI in tapioca starch is an indication of the establishment of a strong starch-protein matrix network in developed biopolymeric films. Also, TGA analysis was performed to determine the percentage degradation in weight of the film samples. The SEM micrographs of the optimized composite biopolymeric film showed a smooth surface without surface cracks.