Preparation and Characterization of Starch/PVA Composite Films Incorporated with Anthocyanins of Purple Sweet Potato
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Abstract:
The sweet potato starch/polyvinyl alcohol (PVA) combined with purple sweet potato anthocyanin extract (PSPE), was used as a film-forming substrate for the preparation of intelligent package films to analyze the freshness of milk, and the mechanical, spectral and color properties of composite films were studied. Results showed that the addition of PSPE improved the mechanical properties of composite films, and at the concentration of 24%, the composite films had a maximum elongation at breakof 87.73% with moderate tensile strength and thickness. The change of ultraviolet-visible spectrum (UV-Vis) of the composite films was consistent with that of the pigment solution, indicating that PSPE exhibited good compatibility with the film-forming substrateand the physiological activity was high. Fourier transform infrared spectroscopy (FT-IR) showed that the hydroxyl groups of PSPE interacted with the hydroxyl groups in film-forming substrate to form intermolecular hydrogen-bonding interactions without affecting the chemical components. In addition, an application test for analyzing the freshness of milk was conducted by using composite films.The results showed that the composite films presented a lilac color in fresh milk and then became reddish and lighter with time, which led to pH decreasing and milk deteriorating. Therefore, the PSPE composite films could realize the intelligent indication of milk spoilage, and the research could provide a reference for the development of intelligent indicator films for milk freshness.
