Sensory and surface-active properties of protein hydrolysates based on Atlantic salmon (Salmo salar) by-products

• Bitter taste development linked to peptides of <2 kDa and high protein recovery (PR).
• Alcalase 2.4L produced more bitter peptides compared to Promod 671L and Protex 7L.
• 1H NMR can be used to measure CMC of protein hydrolysates.
• CMC dependent on both DH and enzyme specificity.
• Direct thermal coagulation give least bitter taste and CMC, but low PR.

Sensory and surface-active properties of protein hydrolysates from Atlantic salmon by-products were compared based on enzyme specificity and molecular weight (MW) distribution at three levels of degree of hydrolysis (DH). The endopeptidases used were Alcalase 2.4L, Promod 671L and Protex 7L. The surface-active properties of the hydrolysates were assessed based on critical micelle concentration (CMC). Hydrolysate hydrophobicity was evaluated based on 2-butanol partitioning as a measure of hydrophobic peptide fraction (HPF). Principal component analysis was used to visualize the relationship between the sensory, surface-active and chemical properties of the hydrolysates. DH, MW distribution and enzyme specificity were all important for the formation of bitter taste and surface-active properties of the hydrolysates. High CMC, i.e. poor surface-active properties, was related to high DH and peptides based on Promod 671L. High bitter taste was positively correlated to peptides of less than 2000 Da and high HPF, DH and protein recovery (PR). Alcalase 2.4L produced significantly more bitter peptides compared to Promod 671L and Protex 7L. A reference sample, made by heat coagulation (>90 °C) and centrifugation of the raw material gave overall superior sensory and surface-active properties, but low PR.

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