Comprehensive application possibility: Construction hydrophilic, amphiphilic and hydrophobic system of modified zein by enzymatic or cysteine modification

Zein, a hydrophobic protein due to high percentage of apolar amino acids, which limits its modification and wide application in the food industry. The interaction between the molecule and water will be changed by introducing different hydrophilic groups into zein, which is the basis aimed at food application. Therefore, zein was modified based on construction of zein-potassium oleate system to obtain hydrophilic, amphiphilic and hydrophobic systems, thus the structure and properties of modified zein were explored in the present study. The results of the three-phase contact angle showed that the constructed zein-potassium oleate system is a hydrophobic system. After enzymatic modification, a hydrophilic system can be obtained. Amphiphilic system can be obtained by cysteine modification. Sodium dodecyl sulfate polyacrylamide gel electrophoresis, gel size exclusion chromatography, hydrophilic-lipophilic balance value, free amino group and sulfhydryl group results can also prove the hydrophilic and hydrophobic system obtained by different modification methods. Ultraviolet, Infrared and fluorescence spectra of zein after enzymatic hydrolysis and cysteine modification indicated that the hydrophilicity and hydrophobicity of the zein microenvironment also changed. This study may provide a feasible approach to broaden the application of zein in food industry.