The Studies On Extraction And Properties Of Hulless Barley Protein

As the by-product of wheat flour，The wheat germ has a rich protein content and balanceamino acid.It is a kind of high-quality protein source of nutrients. For a long time, most millsput the wheat embryo incorporating animal feed, makes this precious resource cannot getsufficient and reasonable utilization. In this paper, the protein of wheat germ was extractedand purified by protease from wheat germ, and then the function and antioxidant activities ofthe protein were studied. The effect of the experiments are bellow:Based on the single-factor and orthogonal experiments, the optimal extraction conditionsof wheat germ protein were as follows: three percent of protease （enzyme/sample, E/S）,hydrolyzing for2.0h, sample/water ratio of1:5, the extraction rate of wheat germ proteincould amount to85.0%, the extraction rate of grease could amount to52.6%.Based on the single factor decoloring experiment, we carry out the Response surfaceAnalysis to get the best decoloring condition: activated carbon decolorizes adding amount of7.7%, decoloring for23min at54℃and pH3.1, the decoloring rate is82.31%, lossing rateof the protein is18.29%. Choose macroporous resin for further purification wheat germprotein hydrolysate, the results show that: DA201-C adsorption effect is the best, thepurification of optimal pH is4.2, temperature is40℃,55%of ethanol have a best effect aselution agent. Throught the decoloring and resin, the purity of wheat embryo purification raisefrom43.82%to76.64%.By amino acid analysis shows that wheat germ protein and wheat germ proteinhydrolysate contain17kinds of amino acids, but both have different levels of amino acids.Among them the human body essential amino acids relatively complete, and the proportion oftotal amino acid respectively content35.30%and34.63%. By the relative molecular weightdistribution, that: the relative molecular weight of wheat embryo hydrolyzed protein issmaller than wheat germ protein. SEM results show: wheat germ protein hydrolysate isdiscontinuous structure, and wheat germ protein molecules area is larger, structure is intact;The infrared spectra show: wheat germ protein component unit give priority to be beta fold,and account for the total amount of39.84%, and secondary structures of wheat germ proteinhydrolysate give priority to be beta corner, and account for the total amount of70.56%.Research results show that the functional properties by alkali soluble acid sinking thewheat germ protein for legal system as well as with soy protein, its solubility with pH value increases in first decreases, then increases, wheat embryo hydrolyzed protein in a wider pHvalue range still shows good solubility; Wheat embryo after proteolytic digestion wasimproved, and the emulsification and wheat germ protein hydrolysate blister sex andsparkling stability are poorer; Wheat germ protein hydrolysate remain oily is good, but holdwater ability is worse than soybean protein isolated and wheat germ protein.Antioxidation experiment results show: the ability of wheat germ protein hydrolysate toclear DPPH· free radicals, OH^-· free radicals, superoxide radical （O₂^-·） and the reductionability is better than wheat germ protein obtained by alkali soluble acid sinking, and have aquantity-efficiency relation with protein concentration. Using ultrafiltration on wheat germprotein hydrolysate grading, antioxidant activity of the small molecular peptide that molecularweight is less than1000Da is significantly stronger than wheat germ protein hydrolysate,slightly weaker than ascorbic acid, and antioxidant activity of protein peptide whichMolecular weight is more than1000Da is weaker than wheat germ protein hydrolysate, butstill stronger than wheat germ protein.