Development of Buckwheat Starch-Capric Acid Complex-Based Film: Process Optimization and Film Characterization

Abstract

To overcome the limitations of starch usage alone, the film formation ability of the buckwheat starch-capric acid complex (BS-CA) was optimized, and the films were characterized. Significant models were obtained for tensile strength (TS) and Young's modulus (YM) of BS-CA film (p < 0.0001). The glycerol/starch ratio, temperature, and their interactions were significant in the YM model (R2 is 0.9851). The BS-CA film had a better water vapor barrier (0.463 ± 0.02 g mm/m2 h kPa), with lower water solubility (WS) (34.18 ± 1.70%) and moisture content (MC) (16.87 ± 0.09%) than the buckwheat starch (BS) film (p < 0.05). It had lower thickness (0.073 ± 0.00 mm) and TS (0.624 ± 0.04 MPa) but higher elasticity (114.60 ± 3.12%). The non-covalent interactions were determined between BS and CA, since new peaks were not observed in the film's FTIR spectrum. BS-CA film had a typical V-type crystalline structure and had slightly lower decomposition temperatures than the BS film. Contact angle measurements (55.19° ± 1.7), and images of AFM topography and SEM showed that the BS-CA film surface was hydrophilic; height and average roughness values were 1014 and 276 nm, respectively, which were quite higher than those of BS film. The results reveal that starch modification with fatty acid is a promising way to develop starch-based films to be used in practical applications.