Search

Under the acidic conditions (pH 4.0), the addition of wheat oligopeptides (WOPs) (25~100 g/L) decreased the thermal stability of purple sweet potato anthocyanins (PSPAs), but enhanced its antioxidant capacity, which increased with the rise of the additive amount. When the addition was 100 g/L, the DPPH, ABTS free radical scavenging capacity and FRAP total antioxidant capacity of PSPAs solution after in vitro simulated digestion were increased by 1.5 times, 34 times and 34%, respectively. After storage at 37 ℃ and 45 ℃ for 7 d, the antioxidant capacity did not change significantly, and it had stronger biological activity and higher stability than those of PSPAs. UV and fluorescence spectra showed that PSPAs can affected the redshift of absorption peak and fluorescence quenching at specific wavelength of WOPs at experimental concentration, which proved the interaction between WOPs and PSPAs. It can be seen from the above that WOPs have the potential to be applied in the development of acidic PSPAs beverages.

In order to improve the gel properties of black rice, mung bean starch, potato starch and corn starch were mixed with black rice flour. The pasting properties and texture properties of compounded system, and the molecular structure characteristics of the complex system were tested, and further analyzed by low-field NMR analyzer, Fourier transform infrared spectroscopy and X-ray diffraction. The results showed that with the increase of starch concentration, the pasting viscosity of the starch-black rice flour complex system increased significantly, while the pasting time and temperature were reduced. Mung bean starch and potato starch significantly enhanced the water holding capacity and swelling capacity of the compound system, while potato starch and corn starch significantly reduced the solubility. All three starches promoted the formation of the gel network structure and improved the texture properties of the gel, including the hardness, elasticity, chewiness and resilience of the gel. In addition, the three starches enhanced the hydrogen bond interaction between the starch chains of the compound system, reduced the water holding capacity of the gel, and enhanced the molecular short-range structure order and relative crystallinity of the system. The above research showed that three kinds of starch improved the quality of black rice gel, and mung bean starch had the best improvement effect.