Influence of sonication pretreatment on antiradical and anti-ACE activity of protein hydrolysates from fermented pork loins

The aim of this study was to assess whether ultrasound treatment (sonification time: 5, 15, and 30 min; constants: ~40 kHz, ~2.5 W cm2) can be applied prior to hydrolysis to enhance the anti-radical and angiotensin converting enzyme inhibiting (anti-ACE) effect of the hydrolysates from fermented pork loins. Enzymatic hydrolysis was performed using pepsin, followed by pancreatin. The influence of meat matrix on the course of hydrolysis, shaped using a lactic acid bacteria (LAB)-based starter culture, was also analyzed. It was found that proteases caused a systematic increase in the content of peptides, while pancreatin limited the peptide content in the protein hydrolysate from the loins subjected to spontaneous fermentation. Moreover, for these tests, sonication time had a negligible effect on the peptides content of the hydrolysates. On the other hand, for the sample of LAB-fermented products, both sonication time and stage of hydrolysis promoted the biological activity of the hydrolysates. Samples from the LAB-fermented meat had more peptides at the stage of digestion with pepsin and pancreatin, exhibiting much faster antiradical and anti-ACE activity compared to the control sample. The obtained results suggest that the use of LAB promotes the release of antiradical peptides during the two-step enzymatic hydrolysis, the duration of which can be shortened to achieve satisfactory biofunctionalities. Additional application of sonication pretreatment allows controlling the course of the hydrolysis, as the pro-health, biological effect of some protein-derived sequences is associated with the content of peptides.