Effect of emerging technologies on the physicochemical and colloidal properties of protein hydrolysate from Pandalus borealis side-streams

Nowadays, most shrimp side-streams are discarded due to the absence of appropriate processing techniques or methodologies for their utilization. This practice not only results in the loss of potentially valuable compounds but also increase organic waste which contributes to an increase in greenhouse gas emission. Emerging techniques based on different methods such as cavitation, high electric field and moderate to low electric field combined with uniform heat, named ultrasound (US) herein applied at 20 kHz, 90 % amplitude, pulsed electric field (PEF) at 5–6 kV/cm, 50 μs pulse width and ohmic heating (OH) at 70 V, 50 °C for 10 and 30 min, respectively, were used to induce protein and peptide structural change and improve colloidal properties. The amino acid composition of the shrimp head and shells, named as side-stream, was evaluated, showing essential amino acid content of 34.5 % of total amino acids. FPLC analysis showed that all treatments induced peptide aggregation with a lower number of peptides with molecular weight below 0.2 kDa and a higher amount of the ones above 0.6 kDa. Intrinsic fluorescence measurements showed that changes in tertiary structure were mainly caused by ultrasound, pulse and continuous methods, and ohmic heating short time treatment. PEF treatments significantly increased surface hydrophobicity and longtime treatment of ohmic heatinginduced aggregation. Fluorescence analysis, H0, and FTIR suggested Changes in protein secondary structure were. Under the applied conditions, PEF 5 kV/cm and pulsed US yielded emulsions with droplet sizes of 1.5 ± 0.07 μm and 6.73 ± 0.22 μm, respectively and highest stability.