Enzymatic hydrolysis using bacterial cultures as a novel method for obtaining antioxidant peptides from brewers' spent grain

Abstract

Hydrolysis of brewers' spent grain conducted in the bacterial cultures entails reduction of workload, economic cost and environmental impact.

Comparative Analysis of the Alkaline Proteolytic Enzymes of Yarrowia Clade Species and Their Putative Applications

“…In the culture of Y. lipolytica, Y. galli, Y. alimentaria, and Y. keelungensis, characterized already as leading proteolytic strains, the concentration of α-amino groups reached 4367µg/mL, 4245 µg/mL, 3939 µg/mL, and 3885 µg/mL, respectively (Figure 6). Interestingly, in our previous work using proteolytic bacteria, the concentration of free α-amino groups in the same BSG-based medium never exceeded 2600 µg/mL [32]. This result clearly shows the benefits of using Yarrowia clade yeast when applying BSG.…”

“…Interestingly, in our previous work using proteolytic bacteria, the concentration of free α-amino groups in the same BSG-based medium never exceeded 2600 μg/mL [ 32 ]. This result clearly shows the benefits of using Yarrowia clade yeast when applying BSG.…”

“…It was more than twice higher than the activity of the control sample (603.73 μM TEAC/g). According to our previous research, the antioxidant activity of the control samples is caused by the partial hydrolysis of BSG protein occurring during media sterilization [ 32 ]. High antioxidant activity of post-culture media of Y. galli , Y. keelungensis , and Y. lipolytica strains resulted mainly from the efficient hydrolysis of spent grain protein (DH% > 60%), which is not the case of Y. divulgata , where DH% did not exceed 30%.…”

“…In our previous work, the antioxidant activity of BSG protein hydrolysates, obtained using the ABTS method directly in proteolytic bacteria cultures, ranged from 345.18 to 1621.31 μM TEAC/g peptides [ 32 ]. In this work, most of the analyzed samples showed a total activity of about 1500 μM TEAC/g.…”

“…For this purpose, the concentration of free α-amino groups was determined using ninhydrin method [ 56 ]. The maximum concentration of α-amino groups detected for each culture was compared to the data obtained for the protein hydrolysis using hydrochloric acid (total hydrolysis), performed as described previously [ 32 ]. The %DH was calculated according to the following equation: where TH (μg/mL) and BH (μg/mL) are the average concentration of α-amino groups obtained, respectively, as a result of the total hydrolysis (TH) or in the yeast culture (BH) calculated per 1 g of BSG sample.…”