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-l batch reactor at pH 7 and 45 °C. 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 °C 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® 2, 4L for the tuna waste solubilisation. However, the Umamizyme stability is lower than Alcalase® 2, 4L.