Preparation Of Hydrolysates From Se-enriched Rice Endosperm Protein And Their Antioxidant Activity And Immunocompetence

Selenium in Se-enriched rice endosperm is always combined with proteins,whichhave quite high bioactivity.This research relates to finding an enzymolysis method toget hydrolysates whose antioxidant activity and immunocompetence were measuredin vitro from Se-containing proteins extracted from Se-enriched rice endosperm withalkali solutions.The relationship between selenium concentration and antioxidantactivity or immunocompetence is also analyzed.Results of this research involve that:1. After screening,maximum extractability was reached when rice endospermwas extracted at40℃for3h with using1:20(w/v),0.07mol/LNaOH.Otherwise,proteins extracted with SDS solutions didn’t show a largerextractabilty than that extracted with alkali solutions.2. Se-containing proteins were processed with tripsin,papain and pepsinrespectively.Then,trypsin appears to be the most desirable for producing peptides withhigher degree of hydrolysis and greater DPPH free radical scavenging activity fromSe-containing rice proteins. The optimum enzymatic hydrolysis condition wasselected at an enzyme than substrate concentration of10%, an substrate concentrationof6%, pH9.0and a temperature of50℃with using an orthogonal experiment. Underthis optimum condition, the DH and selenium contents of the hydrolysate(TPH) was22.69±0.34%and0.372±0.031mg/kg, respectively. And the DPPH free radicalscavenging rates was raised up to78.19±1.4%when sample concentration was2.0mg/mL.Results of reducing activity measurement showed that antioxidant activitywas embodied in TPH.3. According to the results of cellular antioxidant activity of hydrolysates,enzymatic hydrolysates showed a cellular antioxidant activity while extractions ofSDS solutions didn’t show that.The highest antioxidant activity was reached by usingtripsin.A correlation was found out between immunocpmpetence and enzyme solutionmethod and TPH showed the highest immunocompetence in vitro.4. Positive correlation between macrophage cell neutral red ability andselenium concentration or degree of hydrolysis of Se-containing protein hydrolysateswas found, the correlation coefficient obtained was0.792and0.930(P＜0.05).Immunocompetence of Se-containing protein hydrolysates could be affected bythe construction of peptides and selenium generation amino acids.The activity ofinhibiting DCFH oxidation by super oxygen free radical of Se-containing protein hydrolysates showed a significant negative correlation with accelerating macrophagecell neutral red ability, the correlation coefficient obtained was-0.840(P＜0.05).Thus,we can confirm that a correlation between cellular antioxidant activity andimmunocompetence in vitro is existed.