Production of tuna waste hydrolysates by a commercial neutral protease preparation

The fish protein hydrolysates (FPH) are of increasing interest due to their potential applications as a source of bioactive peptides or as nitrogenous substrates for the fermentation media. A waste product from the canning industry was hydrolysed using a commercial protease "Umamizyme". Enzymatic hydrolysis was investigated in a 1-1 batch reactor at pH 7 and 45 degreesC. The influence of the process variables (enzyme/protein substrate ratio ranging from 0.1 to 1.5 % (w/w) protein) was studied with regards to the extent of the proteolytic degradation, the nitrogen released and the molecular weight distribution of the peptides. A degree of hydrolysis up to 22.5% was obtained with an enzyme/substrate ratio of 1.5%, after 4 h of hydrolysis. A linear correlation was found to exist between the hydrolysis degree and the nitrogen recovery. The limiting factor of hydrolysis was deduced from a set of experiments conducted at 45 degreesC and pH 7 where the effects of intermediate substrate and enzyme addition were studied. Results showed that the protease "Umamizyme" performed as effectively as Alcalase(R) 2, 4L for the tuna waste solubilisation. However, the Umamizyme stability is lower than Alcalase(R) 2, 4L. (C) 2002 Elsevier Science B.V. All rights reserved.