Enzymatic hydrolysis of Grass Carp fish skin hydrolysates able to promote the proliferation of Streptococcus thermophilus

BACKGROUNDThe promotion effect on proliferation of Streptococcus thermophilus by enzymatic hydrolysates of aquatic products was firstly studied. The effect of influencing factors of the hydrolysis on the growth of S. thermophilus was investigated. RESULTGrass Carp fish skin was hydrolysed to peptides by enzymatic hydrolysis using protease ProteAX, and for the S. thermophilus growth, the optimal enzymatic hydrolysis conditions were temperature of 60 degrees C, initial pH of 9.0, enzyme concentration of 10gkg(-1), hydrolysis time of 80min, and ratio of material to liquid of 1:2. The Grass Carp fish skin hydrolysate (GCFSH) prepared under the optimum conditions was fractionated to five fragments (GCFSH 1, GCFSH 2, GCFSH 3, GCFSH 4, GCFSH 5) according to molecular weight sizes, in which the fragments GCFSH 4 and GCFSH 5, with molecular weights of less than 1000Da, significantly promoted the growth of S. thermophilus. CONCLUSIONThe hydrolysis process of Grass Carp fish skin can be simplified, and the peptides with molecular weights below 1000Da in the hydrolysates are the best nitrogen source for proliferation of S. thermophilus. This work can provide a fundamental theoretical basis for the production of multi-component functional foods, especially in milk drinks or yogurt. (c) 2017 Society of Chemical Industry