米曲霉固态发酵结合成曲水解法制备大豆抗氧化肽的研究

Preparation of Soybean Antioxidant Peptides by Aspergillus oryzae Solid Fermentation Combined with Controllable Koji Hydrolysis

摘要:

利用米曲霉固态发酵制曲结合成曲水解制备大豆抗氧化肽。分别以豆粕和麸皮为氮源和碳源，研究米曲霉制曲的原料碳氮比(C/N)、制曲培养时间、曲精接种量对成曲水解特性（成曲蛋白酶活、水解度、肽得率、蛋白质回收率）及其水解产物抗氧化活性（抗氧化能力指数ORAC值、DPPH自由基清除率）的影响。在此基础上，通过正交试验研究四因素（包括pH、外源添加大豆分离蛋白、底物蛋白浓度和水解时间）对成曲水解产物抗氧化活性的影响，以期筛选出水解产物抗氧化活性较高的大豆肽。结果表明：制曲条件为：麸皮/豆粕质量比为1/5、培养时间44 h、曲精接种量0.05% (m/m)；成曲水解条件为：pH 7、底物蛋白浓度8%、不添加外源蛋白、水解4 h时，所得成曲的碱性蛋白酶活力可高达3109.85 U/g，曲水解产物的ORAC值可高达2130.22 μmol Trolox equivalent/g peptide，DPPH的IC50值为0.29 mg/mL，具有强抗氧化活性。

Abstract:

Antioxidant peptides from soybean were prepared by solid fermentation with Aspergillus oryzae and combined with controllable koji hydrolysis. With defatted soybean as nitrogen source and wheat bran as carbon source for Aspergillus oryzae, the koji-making conditions were optimized and the protease activity of koji were evaluated.The degree of hydrolysis, peptide recovery and protein recovery were also analyzed. Then orthogonal test was applied to optimize preparation conditions. It was found that the optimum koji-making conditions were as follows: C/N ratio 1/5, culture time 44 h, and inoculum size 0.05%. The optimum hydrolysis conditions were as follows: pH 7, substrate protein concentration 8%, hydrolysis time 4 h and no additional protein needed. Under these conditions, the alkaline protease activity of koji was 3109.85 U/g and the obtained product showed strong antioxidant activity with high ORAC value (2130.22 μmol Trolox equivalent/g peptide) and DPPH scavenging activity (IC50 =0.29 mg/mL).