Study On The Preparation And Properties Of Peanut Protein Gel Induced By Limited Hydrolysis

In recent years,plant based food and meat substitutes are widely concerned.Peanut is one of the most competitive export products in China.It is widely used in the food industry with its unique flavor and high nutritional value.At present most peanut are prepared for oil,the protein content of its by-product peanut meal is high,but because of the limitation of the processing technology of peanut protein and its function needs to be improved,the use of peanut meal is still at the primary stage.Protein gel has high viscosity,water retention and elasticity,which often widely used as a stabilizer or emulsifier in meat products,cereals and dairy products in the food industry.At present,little research is on peanut protein gel,most of the existing research is through high temperature heat induced or supplemented with salts or acids coagulant gel.Research shows that alkaline protease has prompted the protein forming ability of cross-linked network structure.The preparation method of peanut protein gel without adding any coagulant have not been reported.In this study,peanut protein isolate was extracted from low denatured defatted peanut meal.Using alkaline protease to treat peanut protein isolate,and the peanut protein gel was prepared by limited hydrolysis.Physicochemical properties and structure changes of peanut protein gel were studied,and the mechanism of gel formation was discussed.The results are as follows:1.Alkaline protease was used to limited hydrolyze peanut protein,which could make the gel formed at the temperature of 50? to 70?;the peanut protein solution was not able to form gel within 70? without enzyme treatment.2.According to gel hardness index,through single factor and response surface experiments,the optimal technological parameters for preparing peanut protein gel were:enzyme concentration 2.50 U/g,enzymolysis temperature 60?,enzymolysis time 36 min,pH 8.21,under the conditions of preparation of peanut protein gel,the measured value is 1.35 ±0.02 N.3.The physicochemical properties of peanut protein gel were analyzed.Rheological test,creep recovery test,apparent viscosity showed that,the peanut protein gel had typical gel rheological properties;electrophoresis analysis showed that after enzyme treatment,the banding intensity of Arachin II were significantly reduced;DSC results showed that the thermal stability of protein was significantly increased after enzyme treatment,the order of protein structure decreased significantly.4.The secondary structure of peanut protein were analyzed.CD spectrum and infrared spectrum both showed that the enzyme treatment significantly reduced the content of alpha helix,and significant increase the content of beta folding and random coil,but the effect on the content of beta angle was not significant.5.The tertiary structure of peanut protein were analyzed.Results showed that hydrophobic interaction was the main driving force for peanut protein gel,followed by hydrogen bond,ionic bond is not the main chemical reaction;after enzymolysis,the surface hydrophobicity of peanut protein increased;the maximum fluorescence wavelength of fluorescence spectrum were red shift;exposure and total sulfhydryl content increased significantly,and the ratio of them increased significantly.