Proteolytic activity of Lactobacillus sakei, Lactobacillus farciminis and Lactobacillus plantarum on sarcoplasmatic proteins of pork meat

The aim of this study was to assess the proteolytic activiti of various bacteria on the meat sarcoplasmatic proteins. The proteins composition was assayed by SDS-PAGE and capillary electrophoresis after incubation of meat extract inoculated with bacteria. Al strains showed proteolytic activity: a band about 94 kDa disappeared in samples inoculated with L. farmiciminis and L. plantarum and strongly decreased in those inoculated with L. sakei. The intensity of the bands with a molecular weigth between 94 and 38 kDa decreased in all samples. Capillary electrophoresis analysis ascertained the disappearance of the fraction corresponding to 8.64 and 8.66 min retention time in all samples. The bands corresponding to 94 and 38 kDa were, respectively, identified as glycogen phosphorylase muscle isoform and glyceraldehyde 3-phosphate dehydrogenase, by in situ digestion of protein gel bands and peptide map analysis usingMatrix Assisted Laser Desorption/Ionization - Time of Flight Mass Spectrometry (MALDI-TOF-MS):