The effect of sodium nitrite (SN) and sodium lactate (SL) on the growth of three strains of lactic acid spoilage bacteria in vacuum packed cooked pork sausage was examined. Sausage was formulated with SN (0 and 200 ppm) and SL (0, 1 and 2%). Sliced products were inoculated with Lactobacillus viridescens PSC-Y510101, Leuconostoc mesenteroides PSC-Y 539901 or Enterococcus faecalis PSC-Y520101 (ca. 10 CFU/g each), vacuum packed and stored at 10°C for 30 days. The populations of the three strains without addition of SN and SL increased by 4 to 5 log units during the initial 9 days. Addition of 200 ppm SN to cooked pork sausage extended the period to reach 105 CFU/g of L. viridescens, L. mesenteroides and E. faecalis by 9, 4 and 15 days compared with the control (without addition), respectively. Also, addition of 2% SL extended this period by 8 and 9 days, for L. viridescens and L. mesenteroides, respectively. The initial population of E. faecalis in the sausage was not affected by the addition of SL during the 30 days storage. The combination of SN and SL enhanced the inhibitory activity against three strains of lactic acid spoilage bacteria. In conclusion, SN and SL are effective additives for preventing the growth of lactic acid spoilage bacteria in meat products.
Lactic acid bacteria isolated from freeze-dried Georgian (Russia) kefir grains were compared with those in the flora of other kefir grains. The 6 representative isolates were identified as Weissella confusa (GKL1), Lactobacillus kefir (GKL2) and Lactobacillus kefiranofaciens (GKL5, GKL7, GKL9, GKL28) based on phenotypic characteristics and DNA-DNA relatedness. Three of the L. kefiranofaciens strains might be identified as Lactobacillus acidophilus (GKL5, GKL7) and Lactobacillus delbrueckii subsp. lactis (GKL9) from their phenotypic characteristics. L. acidophilus and L. bulgaricus reported previously were presumed to be mutants of L. kefiranofaciens which had lost the productivity of polysaccharide. L. kefir and L. kefiranofaciens have been reported to be constituent strains of the kefir grains but Leuconostoc mesenteroides and Lactococcus lactis described previously were not isolated from either the kefir or kefir grains in this study. Instead of these two species, W. confusa strains were isolated from kefir as a dominant species, but those were not isolated from the kefir grains. These findings suggested that the Leuconostoc and Lactococcus strains disappeared due to the cultural conditions before freeze-drying, and that the fast growing strains of W. confusa contaminated the kefir during activation of the freeze-dried kefir grains.
The hygiene monitoring kit, KONICA SWAB'N'CHECK (domestic trade name; KONICA FUKITORI-MASTER), easily and quickly detects proteinaceous food soils existing in the food processing areas. In this study, the limitation of the detection of the various food soils and the relationship between food residue amounts and E. coli growth were investigated. By use of the kit, 80 mg/m2 of milk, 2 mg/m2 of skim milk, 20 mg/m2 of chicken soup, and 4.2 mg/m2 of albumen were able to be detected. These detectable amounts were 1/3 to 1/400 of the amounts detected by naked eye. Also, the possibility of E. coli growth in small amounts of food soil was suggested. By applying the kit to monitor the degree of the cleanliness, the washing efficacy can be effectively controlled and the self management of sanitation.