Influence of the degree of hydrolysis and type of enzyme on antioxidant activity of okara protein hydrolysates

Abstract

The objective of this work was to evaluate the antioxidant activity of protein hydrolysates obtained by the enzymatic hydrolysis of okara using an endopeptidase (Alcalase) and exopeptidase (Flavourzyme). The reaction was monitored by the pH-stat procedure in which five aliquots were collected during the hydrolysis by each enzyme, corresponding to different degrees of hydrolysis (DH). The antioxidant activities of the aliquots were evaluated by the ABTS, DPPH and FRAP methods. For the hydrolysates obtained using Alcalase, the antioxidant activities increased from: 68.6 to 99.5% (ABTS), 14.5 to 17.7% (DPPH) and 222.6 to 684.9 µM Trolox (FRAP), when the DH varied from 0 to 33.6%. With respect to Flavourzyme, the results were: 67.2 to 88.2% (ABTS), 9.5 to 18.5% (DPPH) and 168.0 to 360.3 µM Trolox (FRAP), when the DH increased up to 5.8%. The results showed that the protein hydrolysates had antioxidant capacities, which were influenced by the degree of hydrolysis and the type of enzyme.

Production of bioactive proteins and peptides from the diatom Nitzschia laevis and comparison of their in vitro antioxidant activities with those from Spirulina platensis and Chlorella vulgaris

“…Generally, the radical quenching activity increased with increase in incubation time, and an increase is observed even after 24 hours incubation with the free radical (data not shown). The efficacy of Alcalase Ò to produce bioactive hydrolysates with high ABTS radical scavenging activity in this study is in agreement with Sbroggio et al (2016). ABTS assay involves an electron transfer reaction (Huang et al, 2005), and values obtained are quite in line with what was expected.…”

“…The efficacy of Alcalase ® to produce bioactive hydrolysates with high ABTS radical scavenging activity in this study is in agreement with Sbroggio et al . (). ABTS assay involves an electron transfer reaction (Huang et al ., ), and values obtained are quite in line with what was expected.…”

“…The stereospecific endopeptidase Alcalase ® resulted in the highest DH, followed by Flavourzyme ® and trypsin the lowest (Figure S1). The efficacy of Alcalase ® is proven in the literature to be the best to produce high‐quality bioactive protein hydrolysates (Sbroggio et al ., ), although Flavourzyme ® , in theory, could produce low molecular weight fragments due to the presence of both endo‐ and exopeptidases. However, in this study, the highest DH of 71% ( P < 0.05) was achieved from Nitzschia proteins, and 68% ( P < 0.05) from Chlorella after 30 min and 65% ( P < 0.05) from Spirulina after 60 min of hydrolysis using Alcalase ® (Figure S1).…”

“…This good correlation may be due to the fact that Folin-Ciocalteu method of determining the total phenolics is also an electron transfer (ET) method as ABTS assay (Huang et al, 2005). This positive correlation decreases slightly with Flavourzyme Ò hydrolysates and showed no correlation with trypsin hydrolysates (Figure S3) emphasising the fact that the bioactivity of protein hydrolysates obtained depended highly on the degree of hydrolyses and the type of proteases used (Qin et al, 2011;Sbroggio et al, 2016).…”

“…This might be due to inactivation of active peptide sequence by exoproteases present in the commercial protease preparations, through the splitting of one or more amino acids from the active N-terminal or C-terminal of the peptides. The antioxidant capacity depended on the degree of hydrolysis and the type of enzyme used (Sbroggio et al, 2016).…”