Effects Of Ultrasound-ionic Liquid Treatment On Physicochemical Properties And Bioactivities Of Hydrolysates Of Glutenin

Wheat gluten,as the by-product of wheat starch milling,is widely utilized in food and feed processing.With the saturation of wheat gluten market,new applications of wheat gluten have been focus of study in the worldwide.In this study,glutenin,a main ingredient of wheat gluten,was used to study the applications of ultrasonic-ion liquid?UIL?treatment technology in enzymatic preparation technology of bioactive peptides.To study the effect of UIL treatment on degree of hydrolysis?DH?of glutenin,response surface methodology was adopted to optimize the conditions of UIL-assisted enzymatic hydrolysis of glutenin.The effects of UIL treatment on physicochemical properties,enzymolysis kinetics and enzymolysis thermodynamics of glutenin were studied.The mechanism of action of UIL treatment on glutenin hydrolysis was revealed.The effects of UIL treatment on bioactivities of glutenin hydrolysate were evaluated by analyzing the changes of antioxidant activity,ACE inhibitory activity and immune activity after UIL treatment.The results showed that the DH of glutenin was affected by the ratio of water to ionic liquids,ultrasonic power,material mass concentration and ultrasonic time in decreasing order.The optimized parameters of glutenin by UIL treatment were as follows:ultrasonic power 288 W,ultrasonic time 6.3 min,ratio of water to ionic liquids?v/v?0.85:1 and material mass concentration 20 g/L.Under the optimal conditions,the DH of glutenin than untreated group increased by 49.65%.Compared with untreated glutenin,After UIL treatment,the ultraviolet spectrum,fluorescence emission spectrum and Zeta potential of glutenin were changed.Surface free sulfhydryl content and total free sulfhydryl content of UIL treated glutenin were increased by 56.74%and 51.09%,respectively.After UIL treatment,contents of?-helix for glutenin was increased by 31.85%,while its contents of random coli,?-sheet and?-turn were decreased by 18.46%,12.44%and 12.10%,respectively.In addition,UIL treatment caused a 42.35%increase in hydrophobicity for glutenin.The results of scanning electron microscopy showed that,after UIL treatment,glutenin become more uniform and loose.SDS-PAGE results showed that the primary structure of glutenin is not changed after UIL treatment.The kinetic models of enzymatic hydrolysis for untreated,ultrasonic treated and UIL treated glutenin were established.The kinetic model of untreated glutenin was=3.78ln[1+?21.41/-0.0087?].The kinetic model of ultrasonic treated glutenin was=4.68ln[1+?19.28/-0.0016?].The kinetic model of UIL treated glutenin was=5.80ln[1+?17.13/-0.0008?].After UIL treatment,the molecular weight polypeptides of glutenin hydrolysate were increased.In addition,UIL treatment caused amino acid composition was changed for glutenin hydrolysate.Compared with untreated glutenin,UIL treatment caused a 50.09%decrease in Ea,a55.41%decrease in?H,a 18.75%decrease in?S and a 0.98%decrease in?G.Compared with untreated glutenin hydrolysate,UIL treatment caused a 33.19%increase in scavenging DPPH radical activity and a 19.67%increase in chelating Fe²⁺capacity for glutenin hydrolysate.Moreover,its reducing power activity was improved evidently.After UIL treatment,ACE-inhibitory activity of glutenin hydrolysate was 27.66%higher than untreated glutenin.The immune activity of glutenin hydrolysate was also significantly enhanced after UIL treatment.This study reveals that UIL treatment can change physicochemical properties and enzymatic hydrolysis characteristics of glutenin.Moreover,the UIL treatment could promote the hydrolysis of glutenin and increase the antioxidant activity,ACE inhibitory activity and immunological activity of its hydrolysates.