Hydrolysis of pork muscle sarcoplasmic proteins by Lactobacillus curvatus and Lactobacillus sake

Lactobacillus curvatus CECT 904 and Lactobacillus sake CECT 4808 were selec ted on the basis of their proteolytic activities against synthetic substrat es. Further, the effects of whole cells, cell extracts, and a combination o f both enzymatic sources on muscle sarcoplasmic proteins were determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and reverse-phas e high-performance liquid chromatography analyses. Strains of both species displayed proteinase activities on five sarcoplasmic proteins. The inoculat ion of whole cells caused a degradation of peptides, whereas the addition o f cell extracts resulted in the generation of both hydrophilic and hydropho bic peptides. This phenomenon was remarkably more pronounced when L. curvat us was involved. Whole cells also consumed a great amount of free amino aci ds, while the addition of intracellular enzymes contributed to their genera tion. L. sake accounted for a greater release of free amino acids. In gener al, cell viability and also proteolytic events were promoted when cell susp ensions were provided with cell extracts as an extra source of enzymes.