Fates of foodborne pathogens in raw hams manufactured rapidly using a new patented method.

To manufacture raw ham in an efficient manner, we recently developed a new system in which presliced pork loin was used, and the processing time was reduced to 5% of the conventional method. This study aimed to examine whether this raw ham could be as safe as ham produced by the conventional method. Pork loin spiked with enterohemorrhagic Escherichia coli serotype O157:H7, Listeria monocytogenes serotype 1/2c, Salmonella enterica serovar Enteritidis, and Staphylococcus aureus were processed using either the new or conventional method. The fate of the foodborne pathogens and behavior of hygiene indicator bacteria were examined. Whereas nitrite had disappeared during the conventional packaging process, the reduced processing time in the new system allowed for the ham to be vacuum packed with retention of the nitrite (6.9±1.2 ppm, P<0.01). This accounts for the prominent decrease in L. monocytogenes (2.3 log reduction in 35 days) and S. aureus (3.3 log reduction in 13 days) counts during storage. E. coli O157 and Salmonella Enteritidis were likely resistant to the nitrite in the ham. However, they were unable to multiply in the ham and decreased gradually as in the conventionally produced ham. The bacteriostatic nature of the raw ham was also indicated by the gradual decrease in coliforms (1.3 log reduction in 13 days) in nonspiked ham. In conclusion, the raw ham produced using presliced pork loin is practically as safe as conventionally produced raw ham. It is worth validating these results in a small-scale production setting.

Inhibitory profile of nonapeptide derived from porcine troponin C against angiotensin I-converting enzyme.

A novel angiotensin I-converting enzyme (ACE) inhibitory peptide (RMLGQTPTK; 9mer) from porcine skeletal troponin C was investigated for its inhibitory profile. This peptide was noncompetitive and as hydrophobic as the known ACE inhibitory peptides. Aminopeptidase M quickly hydrolyzed 9mer, resulting in production of MLGQTPTK and LGQTPTK with inhibitory activities similar to those of 9mer. The main hydrolysis product of 9mer with carboxypeptidase A and B was RMLGQTPT showing very weak activity. Most products derived from 9mer hydrolysis by ACE, aminopeptidase, or carboxypeptidase showed weak but definite ACE inhibitory activities. Thus, 9mer was estimated to be a wholly efficient inhibitor with these fragment peptides.

Paenibacillus macerans possesses two types of 16S rDNA copies in a genome with a length difference of twelve base pairs.

Two Paenibacillus macerans strains, JCM 2500T and MCRI 12, exhibited two types of 16S rDNA copies in their genomes, accompanied by a length difference of 12 bp at positions 203 to 214 (Escherichia coli numbering). The long-type sequences were newly identified for P. macerans 16S rDNA, and the copy numbers were different between the two strains. Both types of 16S rRNA were expressed in each strain, and it was predicted that the polymorphism at this position is located in helix H10, based on a comparison with the E. coli 16S rRNA secondary structure model.

Behavior of psychrotrophic lactic acid bacteria isolated from spoiling cooked meat products.

Three kinds of lactic acid bacteria were isolated from spoiling cooked meat products stored below 10 degrees C. They were identified as Leuconostoc mesenteroides subsp. mesenteroides, Lactococcus lactis subsp. lactis, and Leuconostoc citreum. All three strains grew well in MRS broth at 10 degrees C. In particular, L. mesenteroides subsp. mesenteroides and L. citreum grew even at 4 degrees C, and their doubling times were 23.6 and 51.5 h, respectively. On the other hand, although the bacteria were initially below the detection limit (<10 CFU/g) in model cooked meat products, the bacterial counts increased to 10(8) CFU/g at 10 degrees C after 7 to 12 days.