GENERATION OF BIOACTIVE PEPTIDES IN MEAT RAW MATERIALS EXPOSED TO PROTEASES OF DIFFERENT ORIGIN
There are plenty of methods nowadays used for the technological correction of meat raw materials and increasing the functionality of meat products. Among them, the enzymatic hydrolyses using proteases of microbial, plant or animal origin causes considerable interest. Sarcoplasmic and myofibrillar proteins of meat products are subjected to proteolysis during enzymatic treatment, resulting in the peptides generation, including those with high physiological activity and a pronounced therapeutic and preventive effect. Usually they are low molecular weight compounds consisting of several amino acid residues. It should be noted that, unlike drugs, such peptides are able to rapidly penetrate the gastrointestinal tract membranes and further into the bloodstream and the rest of the organism. The aim of this work was to study the bioactive peptides generation in various meat raw materials due to enzymatic hydrolyses by enzymes of animal (pepsin, trypsin) and plant (papain, bromelain) origin. Bos taurus and Sus scrofa skeletal muscle samples were injected with 5 ml of proteases in 50 g of raw meat. The samples were kept for 40 min at 30 °С for exposure to trypsin and pepsin solutions, 30 min at 30 °С for papain and bromelain. The optimum pH value was not established for the enzymes in the samples, the fermentation process was carried out at the native pH of the raw meat. Humidity in the room was 50-55 %. As a control, the corresponding muscle samples without enzymatic treatment were used. According to the results of a one-dimensional gel electrophoresis under denaturing conditions using sodium dodecyl sulfate (SDS-PAGE), obvious quantitative differences were found in the protein profiles of the studied raw materials, and different profiles were obtained for proteases of different origin. A subsequent two-dimensional isoelectric focusing electrophoresis in an ampholine pH gradient (IEF-PAGE) confirmed the obtained results and revealed the used proteases features. Thus, animal proteases, possessing high specificity, affect only a certain part of muscle proteins, but almost entirely destruct them to small peptides (including low molecular weight) and free amino acids. In addition, a greater proteolytic activity of trypsin compared to pepsin was noted. Plant origin proteases affect the majority of muscle proteins with a sufficiently low specificity and destruct them to many fragments, as evidenced by the presence of numerous new protein fractions on 2D-electrophoregram. Using mass spectrometry (MALDI-TOF MS and MS/MS) some short peptides were detected and identified in samples treated with animal proteases. It was practically not possible to detect short peptides after plant proteases treatment due to the insufficient suitability of mass spectrometry to determine the very low molecular weight of generated peptides. Thus, plant origin proteases generate intermediate fractions of some muscle proteins and bioactive peptides more actively and efficiently. The raw materials processing by proteolytic enzymes, in our opinion, can be regarded as the most effective way to obtain biologically active peptides.