Study On Soybean Meal Solid-state Fermentation And Enzymolysis Characteristics And Application Of Hydrolysates

Soybean meal is the by-product of soybean processing, it has a rich yield and its crudeprotein content is as high as40~50%, so it’s a kind of high quality plant protein resource. Thisarticle studied on the characteristics of soybean meal solid-state fermentation by aspergillusoryzae and enzymolysis, and also studied the feasibility of products’ application in meatballs,in order to provide reference for the realization of soybean meal protein’s high valueapplications.According to neutral protease enzyme activity, the optimal culture medium formula wasthat the quality ratio of soybean meal and water was5:4, glucose addition volume was1.25%,and dipotassium phosphate addition volume was0.20%, after carbon source and nitrogensource optimization. Neutral protease enzyme activity was highly related to the growth ofaspergillus oryzae. During12~24h, neutral protease enzyme activity quickly increased, theneutral protease enzyme activity of High Temperature Meal Koji (HK) and Low TemperatureMeal Koji (LK) were1455.24U/g and1526.81U/g respectively at24h. During24~32h,neutral protease enzyme activity’s increasing slowed down, after32h it continued to increaserapidly and reached the maximum at40h, which were1743.55U/g and1812.48U/grespectively. After44h’s fermentation, the weight of HK lost43.92%, and40.64%for LK.Moisture loss mainly caused the weight loss, accounting for70~85%, and carbohydratemetabolism consumption also led to weight loss. Nitrogen source basically didn’t lose, butnitrogen content increased due to moisture and nutrient consumption. Total acid content (drybasis) content increased as a whole. Koji soluble peptide molecular weight distributionshowed that the proteinase produced by aspergillus oryzae mainly degrade macromolecularprotein whose molecular weight was over10000Da.Koji at different fermentation time such as16h,20h,24h,32h and40h were chose to doenzymolysis under the same condition, it turned out that koji through24h fermentation hadthe highest protein recovery rate (PR) and degree of hydrolysis (DH), which showedenzymolysis efficiency didn’t increase along with the increasing of neutral protease enzymeactivity, and the antioxidant capacity of enzymolysis production was best.During the enzymolysis process of24h fermentation koji, PR and DH showed a rising trend with the the extension of time, and leveled off after22h. DPPH clearance rate andreducing power were on the decline, and there was a significant correlation between them.ORAC showed a trend of down-up-down.22h enzymatic hydrolysates showed a good taste,especially umami and sour, bitter wasn’t obvious. Amino acid content gradually increasedwith the extension, but amino acid content which showed tastes was much lower than thethreshold. Enzymolysis led to peptides (<3000Da) content rising, counting for more than70%, correspondingly peptides (>3000Da) content reducing. Take enzymolysis efficiency,antioxidant ability, and the taste characteristics into consideration, that enzymolysis time wasset at22h was advisable.The characteristics of solid-state fermentation and enzymolysis for two kinds of soybeanmeals were compared, there was no significant difference. According to production cost, HighTemperature Meal was recommended in actual production application. High TemperatureMeal solid-state fermentation and enzymolysis production was used into meatballs, it showedthat soybean peptides (<3000Da) and enzymatic hydrolysates lyophilized powder couldinhibit TBARS value rising and SH content falling which helped to inhibit fat oxidation andprotein oxidation, and slow down pH rising. Meatballs could be preserved for13days at4℃,significantly prolonged the shelf life.