Enzymatic Hydrolysis Of Peanut Meal And Sensory Tatse Of Its Hydrolysates

Peanut meal is a byproduct of the high-temperature oil extraction, because of the hightemperatures﹑pressures and organic solvent extraction, the peanut meal protein was heighlydenaturated, and its nutritional value and functionality was greatly reduced, limiting itsapplication in the food industry. This paper aims at improving the utilization rate of peanutmeal protein, expand its applications, increasing the added value of peanut meal. This paperused trypsin and flavourzyme composite hydrolysis peanut meal, by studying the degree ofhydrolysis, pH variation and the content of nitrogen forms, as well as secondary structure andmolecular weight distribution of hydrolysates in enzymatic processes to investigate thehydrolysis characteristics of peanut meal protein, and used sensory evaluation combinedobjective flavor evaluation tools-electronic Tongue technical Analysis hydrolysates tastecharacteristics, providing theoretical guidance for the preparation of peanut meal flavor base.The results showed that, the pH of peanut meal hydrolysates with the increase ofhydrolysis time showed a downward trend. The degree of hydrolysis increased with theincrease of hydrolysis time, the degree of hydrolysis exponentially growed in4h, while in6-8h was linear growth, the degree of hydrolysis increased slowly after8h, reached20.95%at24h; the extraction rate of soluble nitrogen increased with time increasing, reached amaximum at hydrolysis time180min, then followed by a downward trend; the extraction rateof peptide nitrogen increased with the increasing of hydrolysis time, reached a maximum athydrolysis time180min, then followed by a downward trend.The Fourier transform infrared spectroscopy (FTIR) results of peanut meal hydrolysatesshowed that the content of α-helix was decreased, while β-angle increased, the ratio of α-helixand β-sheet bacame lower with the increasing of hydrolysis time. SEM results showed that theprotein aggregates form of peanut meal changed from closed globular into a sheet byenzymatic hydrolysis, and the protein aggregates became smaller and smaller with theextension of hydrolysis time, it indicated that hydrolysis can destroy the dense micellestructure of peanut meal protein, increase the flexibility of peanut meal protein and make iteasier to be digested.The SDS-PAGE and gel exclusion chromatography results showed that thedouble-enzymatic hydrolysis can quickly degradated acidic arachin which molecular weight isfrom31kDa to43kDa in10min, the content of peptide segment which molecular weightgreater than20kDa decreased rapidly, the content of low molecular weight peptide increasedwith the extension of hydrolysis time; relative to flavourzyme, double-enzymatic hydrolysis can quickly hydrolysis macromolecular protein, relative to trypsin double-enzymatic wasconducived to produce small peptides which molecular weight less than1000Da.Sensory evaluation showed that the sense of umami, sour and salty of hydrolysatesincreased with the extension of hydrolysis time within24h; bitterness and sweetness wasincreased within8h, more than8h, the bitter and sweet of hydrolysates reduced with theextension of hydrolysis time. Electronic tongue result is consistent with the trend of sensoryevaluation, based on the distance of two groups can be visually showed the different betweentaste substances. The result of Electronic tongue showed that umami、sour、salty and bitter ofdouble-enzymatic hydrolysis products increased with the extension of hydrolysis time,consistent with the results of sensory evaluation, the sweet of hydrolysates need further study.Analysis result using DFA method showed that the products of doublel-enzymatic hydrolysiswhich digested24h compared to10min products, its flavor (1.0%MSG) increased15.6%,acidity (0.02%citric acid) increased55%, salty (0.2%salt) increased57%, bitter (0.2%tannic acid) increased55%.