Controlling Salmonella Typhimurium, Escherichia coli O157:H7, Yersinia enterocolitica, and Listeria monocytogenes in nham, a Thai style fermented pork sausage, by lactic acid bacteria

The determination of total aerobic bacteria, Escherichia coli, coliforms, Escherichia coli O157:H7, Clostridium perfringens, and mold in Nham, a Thai style fermented pork sausage, was done during September to November, 2002 at Silpakorn University, Nakorn Pathom, Thailand. About 10%, 37.8%, and 70% out of 90 Nham samples were contaminated with E. coli O157:H7, C. perfringens , and mold, respectively. The aerobic plate count of Nham was in the range of 5.40 to 7.04 log CFU/g. Escherichia coli and coliforms could not be detected.; Lactobacillus plantarum, Lactobacillus sakei, Leuconostoc mesenteroides subsp. mesenteroides, Pediococcus acidilactici, Pediococcus pentosaseus, Lactacel 115, and natural cultures were used to produce Nham at 37°C. Lactic acid bacteria reduced Nham pH to the desired value (<4.6) more rapidly than natural cultures. Lactacel 115 was the most suitable starter culture for Nham production and for the control of Salmonella Typhimurium, E. coli O157:H7, Yersinia enterocolitica, and Listeria monocytogenes.; Vacuum packaging helped in the development and maintenance of cured color in am. It provided higher value of CIE a*, Saturation Index, and the 650/570 nm ratio of Nham than heat sealed packaging. Most lactic acid bacteria tested did not show synergistic effect with vacuum packaging on the control of S. Typhimurium, E. coli O157:H7, Y. enterocolitica , and L. monocytogenes.; Fermentation temperature at 42°C showed the best pH reduction and inhibition of S. Typhimurium, E. coli O157:H7, Y. enterocolitica, and L. monocytogenes in Nham fermented by Lactacel 115 but this temperature caused unacceptable appearance and odor to the product. The most suitable temperature for Nham production by Lactacel 115 was 37°C.; Dried plum mixtures, garlic, and sodium diacetate showed synergistic effect with Lactacel 115 on the inhibition of S. Typhimurium, E. coli O157:H7, Y. enterocolitica, and L. monocytogenes in Nham. The use of Lactacel 115 with 3% chopped garlic, 3% garlic extract and 1.5% chopped garlic, or 5% garlic powder along with 0.25% sodium diacetate and 3% fresh plum juice concentrate were the most suitable combinations for Nham production based on color, odor, and the control of S. Typhimurium, E. coli O157:H7, Y. enterocolitica, and L. monocytogenes.; The use of sodium nitrite at 125 ppm along with 550 ppm sodium erythorbate provided greater cured color in Nham than sodium nitrite at 100 ppm or 125 ppm alone when Nham was fermented by Lactacel 115 at 37°C.