Characterization of a seafood-flavoring enzymatic hydrolysate from brown alga Laminaria japonica

Abstract

A seafood-flavoring enzymatic hydrolysate was prepared from brown alga Laminaria japonica. Response surface method was utilized to optimize the degree of hydrolysis and yield of the preparation process. The results indicated that the optimal conditions for the seafood flavoring production were as follows: temperature 50 °C, pH 7.5, solid–liquid ration 1:7 (g/mL), enzyme concentration 9.34%, and reaction time 21.3 h. Under this condition, the yield achieved was 29.90 ± 0.07%, and the degree of hydrolysis was 8.91 ± 0.24%. Amino acids and volatile aromatic substances of the enzymatic hydrolysate were subsequently determined by high performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry, respectively. Electronic tongue and electronic nose were used to assess the taste and flavor of the hydrolysate, respectively. Hexanal (43.31 ± 0.57%), (E)-2-octenal (10.42 ± 0.34%), nonanal (6.91 ± 0.65%), pentanal (6.41 ± 0.97%), heptanal (4.64 ± 0.26) and 4-ethylcyclohexanol (4.52 ± 0.21%) were the most abundant flavor compounds in the enzymatic hydrolysate with % peak areas in GC–MS. The contents of aspartic acid (11.27 ± 1.12%) and glutamic acid (13.79 ± 0.21%) were higher than other free amino acids in the enzymatic hydrolysate. Electronic tongue revealed a taste profile characterized by high scores on umami and saltiness, consistent with the HPLC results.