Effect of ultrasound pretreatment complex glycation on the structure and functional activity of phycocyanin modified by mannose

Food processing is often destructive to active nutrients, thus limiting the application range of bioactive phycocyanin (PC). In this study, ultrasound pretreatment complex glycation was used to modify PC, and the changes in structural characteristics, fluorescence properties, and functional activities before and after processing were further discussed. The results showed that the properties of ultrasound pretreatment can significantly accelerate the glycation process. Compared with the glycation-modified PC (MPC), the ultrasound pretreatment complex glycation-modified PC (UMPC) had higher free sulfhydryl content and surface hydrophobicity, resulting in better surface properties, which were reflected in the foaming and emulsifying properties. Fourier transform infrared spectroscopy, circular dichroism spectroscopy, and fluorescence spectroscopy verified that UMPC had more alpha-helix structures and better fluorescence properties. free radical scavenging experiments also demonstrated its stronger antioxidant activity. In addition, the properties of UMPC showed a trend of increasing and then decreasing with the rise in ultrasound power, with the best at 200 W for 15 min. Overall, ultrasound pretreatment complex glycation is an ideal means of protein modification, which can improve modification efficiency and functional activity, broaden the application range of PC in the food industry, and make a new attempt to protect its biological activity