Hydrolysis of Atlantic salmon (Salmo salar) rest raw materials—Effect of raw material and processing on composition, nutritional value, and potential bioactive peptides in the hydrolysates

• Composition of salmon rest raw material, is reflected in the protein hydrolysate.
• Excess heating before hydrolysis, decrease nutritional value and DH in hydrolysate.
• Similar performance of endogenous enzymes and papain + bromelain in hydrolyzing viscera.
• Papain + bromelain gave more different peptides, total bioactive motifs than Protamex.
• Industrial upscaling is not direct reflection of laboratory hydrolysis.

This study evaluates the composition, nutritional value, and potential bioactive peptides in hydrolysates obtained from different Atlantic salmon rest raw materials. The effect of enzymes (endogenous enzymes, Protamex, and papain plus bromelain), pretreatments, and industrial-compared to laboratory-scale production was evaluated. Proximal composition of the hydrolysates reflected the composition of the starting material. Removal of oil by slight warming (40 °C) before hydrolysis of viscera did not influence amino acid composition, nutritional value, or peptide analysis. However, excessive heating (70 °C) of viscera before hydrolysis reduced protein content, nutritional value, free amino acids, and the degree of hydrolysis (DH) compared to other viscera hydrolysates produced with papain plus bromelain with active endogenous enzymes. Hydrolysis of viscera with only endogenous enzymes was similar to hydrolysis with Protamex or papain plus bromelain concerning proximal and total amino acid composition, DH, nutritional value, and number of different bioactive motifs in the hydrolysates. However, the number of different peptides and the total number of bioactive motifs was higher when using papain plus bromelain compared to Protamex with viscera-containing starting material. Differences between laboratory- and industrial-scales of production of hydrolysates appear to be mainly due to lower efficiency in the hydrolysis, separating processes, and storage conditions.

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