Effect Of Protease On The Characteristics Of Gluten Protein Glycosylation Products And Quality Of Biscuits

Gluten proteins have large molecular weight and low solubility in water.Glycosylation after enzymatic modification can significantly improve the solubility and processing properties of gluten proteins.However,the glycosylation reaction with high temperature would produce advanced glycation end products(AGEs),which are harmful derivatives of the Maillard reaction,and polyphenols will inhibit the generation of AGEs and enhance the safety quality of baked goods.Therefore,Alcalase、Dispase and Papain were used to prepare gluten proteolytic products and analyze the functional and structural properties of their gluten protein glycosylation products in this paper.Secondly,the generation of fluorescent AGEs was measured,and the relationship between the properties of gluten proteolytic products and the generation of fluorescent AGEs in the Maillard reaction products(MRPs)was investigated.Finally,according to the properties of gluten protein glycosylation products and the generation of fluorescent AGEs,suitable proteases were selected to make tough biscuits.The addition of proteases in tough biscuits properly degraded gluten proteins and inhibited the generation of fluorescent AGEs by adding natural extracts.The results will provide theoretical basis and technical reference for the processing characteristics of gluten protein and the improvement of baked food quality.Firstly,gluten proteins were enzymatically digested using Alcalase、Dispase and Papain,and the enzymatic products were treated in combination with the Maillard reaction,and the functional and structural properties of gluten protein glycosylation products were determined.The results showed that the enzymatic hydrolysis significantly improved the functional properties of gluten protein glycosylation products,such as solubility,oil-holding,foaming and emulsification(P<0.05),and the improvement effect of Alcalase and Dispase was the best.The improvement of foam stability and emulsification stability was not significant.In addition,enzymatic hydrolysis increased the content of free sulfhydryl groups and substances with UV and fluorescence absorption in gluten protein glycosylation products.The surface hydrophobicity of the gluten protein glycosylation products was reduced.In addition,FTIR results showed that enzymatic hydrolysis promoted the level of the glycosylation and the generation of AGEs precursors.Scanning electron microscopy revealed that enzymatic hydrolysis reduced the volume of the polymer in the gluten protein glycosylation products.Second,the relationship between fluorescent AGEs and the properties of gluten protein enzymatic digestion products was explored.The degree of hydrolysis of gluten proteins,molecular weight of enzymatic products,antioxidant properties and free sulfhydryl content all had significant effects on the fluorescent AGEs.The hydrolysis degree and free sulfhydryl content of gluten proteins were positively correlated with the content of fluorescent AGEs.After the enzymatic digestion time reached 60 min,the protein hydrolysis degree increased(P<0.05),but the generation of fluorescent AGEs did not change significantly(P>0.05).Besides,it was found that the degree of hydrolysis:Alcalase>Dispase and the amount of fluorescent AGEs generated:Dispase>Alcalase(P<0.05)at the same enzymatic time.The molecular weight distribution,DPPH radical scavenging rate,ABTS radical scavenging rate,hydroxyl radical scavenging rate and total reduction capacity of the enzymatic digestion products were further analyzed.The results revealed that the enzymatic digestion products of Alcalase contained more low-molecular weight components and had higher antioxidant capacity.While the enzymatic digestion products of Dispase contained more high-molecular weight components and had lower antioxidant capacity.Finally,Alcalase was selected to improve the quality of tough biscuits based on the properties of enzymatically modified gluten protein glycosylation products and the amount of fluorescent AGEs produced.The experimental results of the effect of Alcalase on dough properties showed that Alcalase increased the free sulfhydryl content and decreased the disulfide bond content in the dough(P<0.05),thus decreasing the polymer content in gluten proteins and leading to a decrease in the hardness and chewiness of tough biscuits.Alcalase reduced the energy storage modulus G′and loss modulus G″of the dough,which decreased the elasticity and viscosity of the dough,leading to the increased flakiness of the tough biscuits.The moisture distribution showed that Alcalase increased the mobility of water in the dough and decreased the mobility of weakly bound water.The migration of weakly bound water to bound water and the decrease of total moisture content in the dough system facilitated the storage of biscuits.Besides,Alcalase significantly decreased the L~*value and significantly increased the specific volume,a~*,b~*values and browning index(YI)of tough cookies(P<0.05).Alcalase improved the sensory score of tough biscuits,and the best sensory score of88.9 was obtained when added at 0.04%,which was 13.6 points higher compared to the blank.Nevertheless,Alcalase significantly increased the content of fluorescent AGEs and pentosidine in the biscuits while improving the quality of tough biscuits(P<0.05).The addition of TPs,CA and L-CM to tough biscuits revealed that they inhibited fluorescent AGEs in biscuits by 14.24%,52.34%and 18.31%,respectively.The inhibition rates of pentose were4.21%,53.25%and 7.12%,respectively.And EC in TPs had the strongest inhibitory effect on fluorescent AGEs and pentose in tough biscuits,which were 9.58%and 39.53%,respectively.