The Effect Of Extrusion And Enzymatic Hydrolysis On Structure Of Zein And The Properties Of Protein Hydrolyzate

Corn gluten meal(CGM), contained more than60%(w/w) protein, was the majorby-product of corn wet milling. There exists zein in this corn gluten meal. The poor solubilityand digest difficulty of CGM restrict its application in food industry. Thus, how tomanufacture further and modify this by-product becomes a serious question that needs to besolved urgently. Our research is of great importance to promote the production effect andhealthy development of corn processing industry, as well as diversification of the productionof corn protein. Our main research content and conclusions are as follows:(1) Bacillus natto NP-2was mutagenized with ultraviolet. The plus-mutant NP-2-111with genetic stability was obtained by screening with transparent zone method and shakingculture method, which increased the soluble protein content in the fermentation by1fold,compared with the original strain.(2) Studied the structure and components characteristics of modified zein with highperformance liquid chromatography and spectroscopy. The results showed that modificationhad effect on the basic components of zein, and the amount of component had changed.circular dichroism spectra of zein had two negative peaks between195and230nm, and thesecondary structure contained great amount of a-helix and random curl structure. The contentof sulfhydryl groups in modified zein was less than original zein, and the surfacehydrophobicity was higher. The denaturation temperature of modified zein was higher thanoriginal zein, except for the zein that extracted from extruded CGM.(3) Analyzed the promoting physiological activity of alcohol metabolism of corn proteinhydrolysates from different enzyme hydrolysis CGM based on the variations of ADH andGST activities in liver. The result showed that corn protein hydrolysates from the singleenzyme hydrolysis and dual enzymatic hydrolysis of CGM significantly enhanced ADH andGST activities, which demonstrated that corn protein hydrolysates can accelerate the catalyticconversion of ethanol in the body. The activities of ADH and GST decreased with time.When the hydropolysis time reached6h, the ADH and GST activities of the sample group isclose to the model group.(4) Extrusion of CGM was hydrolyzed by Alcalase, and researched the properties of cornprotein hydrolysates. The results showed that hydrolysis could increase the solubility of cornprotein hydrolysates obviously. When CGM was hydrolyzed for150min, the solubility of hydrolysates were enhanced by2.37-3.31times compared with solubility of nonhydroilzedCGM. The viscosity, bubble generation, bubble stabitity and emuisibility of the hycholysatesincreased as the hydrolysis time increased, while the emulsiion stability of the hydrolysateswas much less than that of nonhydroilzed CGM.