Preparation of high emulsifying performance TGase-induced Cyperus esculentus protein hydrolysate glycosylation product and physicochemical properties

This study primarily focuses on the utilization of Cyperus esculentus , which is mainly used for oil extraction. The Cyperus esculentus protein (CEP) hydrolysates glycosylated product was prepared under the mediation by transglutaminase (TGase) with glucosamine. Response surface methodology was used to optimize the preparation process for the glycosylated products, with the optimal conditions being a TGase addition of 21 U/g, a ratio of protein hydrolysate to glucosamine of 3:1, and a reaction time of 1.5 h.The degree of grafting for the glycosylated products was 40.72%. The glycosylation product prepared under this condition exhibited excellent emulsifying activity index (EAI 64.75 m 2 /g), which was slightly lower than the theoretical value of 66.15 m 2 /g. It can be attributed that the actual reaction time was longer than the theoretical time, and the slight rise in viscosity of the reaction mixture has caused some aggregation, leading to a minor reduction in the emulsifying property of the glycosylated product. Infrared spectroscopy, fluorescence spectroscopy, UV - visible absorption spectroscopy and NMR results indicated that the internal groups of Cyperus esculentus protein changed after enzymatic hydrolysis and glycosylation, confirming the occurrence of both processes. The thermal stability of the glycosylated products has been enhanced, and their antioxidant properties have also been improved. This study provided a new option of protein emulsifier based on plants and supplemented methods and theories for protein modification. The obtained glycosylated protein emulsifier has potential research value in applications of food processing, cosmetic manufacturing and drug encapsulation, etc.