Generation of bioactive peptides in meat raw materials exposed to lysates of bacterial starter cultures

Nowadays, preparations based on bacterial lysates are mainly applied in medicine. In food industry, bacterial lysates are still not widely used, in particular for manufacturing meat functional foodstuff. Though their potential for functional foodstuff production is predictable, the efficiency and specificity of action which depend on the characteristics of the strain and the method of cell disintegration require study. A set of peptidases identified in starter cultures, in particular endo-peptidases, aminopeptidases, dipeptidases, tripeptidases, and proline-specific peptidases stimulate interest in the lysates of these microorganisms for food biotechnology. In this work, we have shown that lysates of Pediococcus pentosaceus 28, Staphylococcus carnosus 108, Lactobacillus curvatus 1, P . acidilactici 38, L . sakei 103, L . sakei 105, L . curvatus 2, L . acidophilus AT-41 that we obtained by physical destruction of bacterial cells have the widest spectrum of enzymes and biologically active substances. Our goal was to determine the biochemical composition and enzymatic activity of the lysates of starting bacterial cultures and their role in the formation of biologically active peptides in raw meat. The bacterial suspensions were exposed either to lysozyme treatment followed by separation of the extract from the cell debris by centrifugation, or to ultrasonic treatment to compare two methods of cell destruction. The physical method was proved to be the most effective. For biochemical characterization, the proteolytic, lipolytic and collagenase activities of the lysates, and the concentration of organic acids, proteins, and free amino acids were measured. Enzymatic activities of the lysates were determined using API®ZYM tests. The Lactobacillus curvatus 2, Lactobacillus acidophilus AT-41, Pediococcus acidilactici 38 and Staphylococcus carnosus 108 lysates showed the widest range of intracellular enzymes, including leucine and valine arylamidase, acid phosphatase, naphthol-AS-BI-phosphohydrolase, and b-galactosidase. The proteolytic activity was the highest in Staphylococcus carnosus 108 (115.94 proteolytic capability PC units per mg protein), Lactobacillus acidophilus AT-41 (66.7 PC units per mg protein), Lactobacillus curvatus 1 (91.03 PC units per mg protein), and Lactobacillus curvatus 2 (72.20 PC units per mg protein) as compared to other strains. The level of malic, lactic and succinic acids in the lysates varied in the range of 0.002-0.02, 0.02-0.06, and 0.2-0.9 mg/100 g, respectively. The highest enrichment in free amino acids with 13 AA detected out of 17 AA studied was characteristic of P. acidilactici 38 lysate while only 7 AA were detected in the L. sakei 105 lysate. A comparison of 2D electrophoregrams of fermented raw meat showed both general effects on reducing total proteins and the lysate-specific effects toward various proteins, e.g. formation of protein conjugates and cleavage of target proteins, in particular actin skeletal muscle. Therefore, lysates of the studied starter cultures can serve as a source of various enzymes for practical use in the food industry, for example to improve the functional, technological and biocorrective characteristics of meat products.