| Abstract [eng] |
The aim of this research was to evaluate the effect of animal protein treatment by some biotechnological means to their digestability. In this research kinetics of protein hydrolysis during in vitro digestability of cross-linked proteins in different dairy products and pork meat aged in different conditions, was evaluated. Drinking milk, sour milk and acid induced curd were made from transglutaminase treated milk and their quality was evaluated on the basis of rheological chracterisation. Pork loin (musculus longissimus dorsi) samples were aged at 3 oC covered by different films: film PA / PE (Supravis Group Spolka Akeyjna), film PET / Alox (AZ-Pack) and without film (control). Aging duration of all samples – 4, 8, 12 and 22 days. The in vitro digestion procedure of both, milk and meat, samples was carried out according to INFOGEST protocol. The extent of protein hydrolysis was evaluated by measuring total peptides and free α-amino groups content released during the gastric and duodenal stages of in vitro digestion. Also, released free amino acid content, peptide profile, ACE inhibition and antioxidant activity of peptides after digestion of different meat samples in duodenal stage, were evaluated. It was shown that dairy proteins cross-linking caused higher viscosity and water-holding capacity of the products. Transglutaminase addition to milk induced the significant decrease (P < 0.05) in the rate of the protein hydrolysis at all points of in vitro digestion. For transglutaminase treated and not treated milk the rate of hydrolysis was 42.89% and 45.16%, respectively. For the sour milk the rate of protein hydrolysis was 52.79% for transglutaminase treated product and 60.18% for the control. Curd made from transglutaminase treated milk showed a protein hydrolysis degree of 40.85% and 58.23% for the control. Secondly, it was determined that the rate of protein hydrolysis of aged meat was significantly higher than that of the control samples. The duration of aging was shown to be the critical and more important (P < 0.05) parameter where the highest rates of protein hydrolysis (57.59-58.04%) and the highest amount of free amino acids (76.34%) at the end of gastrointestinal digestion of meat were achieved after 22 days of aging. Results revealed that no significant differences (P > 0.05) between in vitro digestibilities of pork meat samples aged covered by films and the control (without films) throughout the digestion of cooked meat. |
