Whey Protein Fermentation with Aspergillus niger: Source of Antioxidant Peptides

Abstract

Aspergillus niger is a filamentous fungus that through its proteolytic activity, as a result of its proteases, hydrolyzes whey proteins into smaller peptides. These peptides are characterized by antioxidant properties due to the presence of specific amino acids, such as histidine, tyrosine, tryptophan, cysteine, and methionine, which have been shown to have antioxidant effects. Considering the above, peptide extracts derived from the fermentation of a lactic serum substrate with Aspergillus niger were obtained, which were partially purified by precipitation with ZnSO4/acetone; subsequently, the antioxidant capacity was evaluated by spectrophotometric techniques as 2,2-azinobis-3ethyl benzothiazole-6-sulfonic acid (ABTS▪+), diphenylpicrylhydrazyl (DPPH▪), in 96-well microplates, these analyses showed that these extracts have an antioxidant activity higher than 50%; likewise, the amount of thiol groups (-SH) was determined to be higher than 29 nmol/μL and the superoxide dismutase activity (SOD) with values above 0.010 SOD units/mL. For this reason, it is proposed that they can be studied in the future as substances within a food supplementation or in the therapeutic field.