Physicochemical and sensory characteristics of soya protein isolate hydrolysates with added substrate-like amino acids

Soya protein isolate (SPI) with or without added substrate-like amino acid was subject to enzymatic hydrolysis catalysed by commercial proteases (Alcalase 2.4 L, flavourzyme and pancreatin). Addition of a small amount of amino acids (amino acid: SPI = 1: 2500, mol g(-1)) during hydrolysis would cause a significantly (P < 0.05) reduced protein recovery, increased degree of hydrolysis, and altered amino acid composition and antioxidant activities of SPI hydrolysates. The SPI hydrolysates prepared with added Asp, Arg or Lys exhibited a higher antioxidant activity than the control. The bitterness of SPI hydrolysates was largely reduced upon addition of Met, Asp or Glu during hydrolysis, whilst the umami taste and mouthfeel-liking were remarkably increased. Therefore, adding amino acid during hydrolysis is a feasible and beneficial approach to improve both the functional and sensory properties of SPI hydrolysate.