Corn starch/polyvinyl alcohol (PVA) composite films containing different concentrations of tea polyphenols (TP) were fabricated by casting. Scanning electron microscopy and atomic force microscopy images showed that when the TP content was less than 8%, the films were relatively uniform, but with increasing TP concentration, the films became rougher and uneven. Fourier transform infrared, 13C nuclear magnetic resonance, and X‐ray diffraction techniques were used to investigate the interactions between TP, starch, and PVA. The incorporation of TP deepened the color and increased the opacity and solubility of the films. The tensile strength and elongation at break first increased and then decreased with increasing TP content. Furthermore, the addition of TP increased the antioxidant activity of the films, specifically, their ability to scavenge 2,2‐diphenyl‐1‐picrylhydrazyl and 2,2′‐azinobis (3‐ethylberizothiazoline‐6‐sulfonic acid). The addition of TP can effectively enhance the performance of starch composite films and their potential for application in antioxidant food packaging.
Native rice starches were treated with five periods of ultra-high pressure homogenization (UHPH) under each of 60, 80, 100, 120, 140 and 160 MPa, respectively. The morphological, structural and physicochemical properties of starches treated with UHPH were examined. The mean particle diameter of starch nanoparticles ranged between 154.20 and 260.40 nm. SEM revealed that the granular amorphous region of starch granules was damaged under pressures between 60 and 80 MPa, and the crystalline region was further destroyed under pressures as high as 100–160 MPa. DSC demonstrated that the gelatinization temperatures and enthalpies of nanoparticles reduced. The relative crystallinity reduced from 22.90 to 13.61% as the pressure increased. FTIR showed that the absorbance ratio at 1047/1022 cm−1 decreased, and increased at 1022/995 cm−1. RVA results indicated that the viscosity of starch samples increased between 60 and 120 MPa, and the reverse effect was observed under 140 and 160 MPa.
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