Preparation Of Polypeptides From Wheat Gluten And Its Effects On Functional Properties Of Mice

Wheat gluten is a by-product of starch industry, which is separated from wheat flour andwidely used as a high protein resource in food and feed industry, but the insolubility andviscoelasticity under neutral pH condition limit the scope of its application. In this study,wheat gluten was hydrolyzed by proteases and the indexes of the degree of hydrolysis (DH),amino acids, polypeptides content and molecular weight distribution were determined toprepare the proper weight molecular distribution of wheat gluten polypeptides (<3000Da).Meanwhile, the animal experiments were used to explore the effects of the wheat glutenpolypeptides on the growth, immune and anti-fatigue function of experimental animals.The single factor experiments were used to the processing to determine the optimumenzymolysis conditions of wheat gluten polypeptides preparation. The results showed that theneutrase could hydrolyze the wheat gluten with a mild, controllable, and environment friendlyreaction. The optimum enzymatic hydrolysis were obtained as follows: temperature,52℃; pH,6.5; reaction time,4h; wheat gluten substrate concentration,10%; addition of neutrase,12000U/g. Based on the optimum conditions, the degree of hydrolysis was15.8%, the dissolutionrate of wheat gluten was72.02%, and the polypeptides content was28.90mg/mL. As a result,the wheat gluten hydrolysate contained42%polypeptides,29%low molecular weightpolypeptides, and the distribution of polypeptides molecular weight in the180-3000Daaccounted for70%of total polypeptides.The spray drying process was used to produced the wheat gluten polypeptides powder.The optimum process was obtained: inlet temperature was160℃, outlet temperature was70℃, liquid temperature was45℃, and the flow rate was0.1mL/s. Under the aboveconditions, the polypeptides powder yield was74.11%, with7.01%moisture content.the study found that the effect caused by wheat gluten polypeptides on the growthcharacteristics of mice was more significant with higher DH of hydrolysate, shorter fragmentlength of polypeptides and lower molecular weight distribution of polypeptides in the range ofenzymatic hydrolysis of controllable based on the DH within20%. However, when the DH ofhydrolysate was higher than15%, there was no significant effect on the meat feed ratio andthe growth indexes of mice by adding wheat gluten polypeptides (P>0.05).The mice was used as the experimental animal in this study to research the influence ofwheat gluten polypeptides on the growth characteristics, immune properties and anti-fatigueproperties of the mice.The results showed that the addition of wheat gluten polypeptides infeed could reduce the average food intake of mice with a correlation coefficient of-0.667,while the amount of body weight of the mice and the ratio of feed to meat increased. Thewheat gluten polypeptides could also improve the mouse fecal mositure content and the crudeprotein digestibility, which indicated that wheat gluten polypeptides could improve theutilization rate of protein and the metabolism of intestine of mice, and contributed to thegrowth performance of mice. For the immune characteristics, wheat gluten polypeptides had asignificant effect on phagocytic rate, the content of IgG and IgM, compared to basal dietgroup (P<0.01). It indicated that wheat gluten polypeptides could enhance the immunefunction of mice. For the anti-fatigue properties, the application of wheat gluten polypeptides could enhance the anti-fatigue effect of mice. The possible mechanism of anti-fatigue of micemight be attributed to the low molecular weight polypeptides material or free amino acidswhich could increase the hepatic glycogen reserves, and reduce the content of blood lacticacid.