Storage stability of soy protein isolate films incorporated with mango kernel extract at different temperature

摘要

This research investigated the storage stability of antioxidant films made from waste and by-products which are soy protein isolate (SPI) and mango kernel extract (MKE) stored at room temperature (25 degrees C), refrigeration temperature (4 degrees C) and frozen temperature (-18 degrees C) for 90 days. The thickness of the films was maintained from 0.050 to 0.058 mm until the 90th day. The colour properties of SPI films incorporated with MKE (SPI + MKE) were generally not significantly affected by time and temperature except for the b value. All the films turned darker over the storage time. There was no dominant factor between temperature and time for the mechanical properties; all the films showed an increase in tensile strength and Young's modulus, and a decrease in elongation. The antioxidant activity of the films was determined by the total phenolic content and radical scavenging activity of DPPH and ABTS. SPI + MKE film at 25 degrees C showed the highest antioxidant activity as compared to films stored at 4 degrees C and -18 degrees C in all the analyses, with the result being significant in DPPH and ABTS analyses. The film stored at 25 degrees C showed 26 to 50% higher (p 0.05) TPC than films stored at 4 degrees C and -18 degrees C, respectively and had the highest antioxidant activity (54%) in ABTS analysis (p 0.05). SPI + MKE film stored at 25 degrees C also showed only 1% depreciation of radical scavenging activity (RSA) throughout the storage time. The highest decrease (4%) in antioxidant activity was recorded for SPI + MKE film stored at -18 degrees C, although it was considered very low. This shows that the antioxidant activity of the films is stable for 90 days of storage.