본 연구의 목적은 L. monooytogenes에 대한 LP system의 항균효과를 측정하기 위하여 수행되었다 초기 접종수준(10², 10⁴, 10^(7) CFU/ml), LP의 농도는(10, 20, 30 ppm), 그리고 저장온도(5, 10, 15℃), 배지종류(TSB-YE, UHT milk)에 따라 L. monocytogenes에 대한 항균효과를 측정 비교한 결과 초기접종수준을 10²cfu/ml로 하였을 때와 LP농도는 10 ppm 및 5℃로 배양에서 항균력이 높게 나타났다. UHT milk를 이용한 LP system의 항균효과는 Tryptic soy agar를 이용한 시험결과와 비슷하게 나타났다.

To investigate the antimicrobial effect of polyphosphates as a food additive, the growth and structural change of Listeria monocytogenes Scott A were examined in relation to polyphosphates concentration and incubation temperature. Up to 10,000 ppm of polyphosphates, the growth rate of strain was gradually inhibited with increasing polyphosphates concentration and decreasing the incubation temperature. Minimal inhibitory concentration of polyphosphates to the growth of strain was about 12,000 ppm. It was observed, using both scanning electron microscopy(SEM) and transmission electron microscopy(TEM), that 0.9% polyphosphates treatment was resulted in the destruction of cell wall and outflow of cell ingredients. The antimicrobial effects of polyphosphates were more effective than those of dehydroacetate and potassium sorbate at 13℃ and 4℃. The growth rate of the strain in beef was significantly inhibited by the treatment of 0.9% polyphosphates and storaged at cooling temperature.

Highly lethal Listeria monocytogenes, causing bromatoxism through vegetables, dairy products, meat products and shellfish etc, was examined for possible contamination in market beef. USDA, FDA, Malthus and Modified Cold Enrichment methods were used for the detection of Listeria spp.. Samples of domestic and imported market beef were collected from local meat shops at Seoul, Korea. Total two hundreds and six of Listeria spp. were isolated and identified from beef samples. L. welshimeri was the most abundant Listeria species in market beef. Among 206 isolates, the number of L. welshimeri was one hundred and twenty-one(44.8%). The numbers of isolated L. innocua, L. murrayi, L. monocytogenes, L. grayi, L. seeligeri, and L. ivanovii were 49(18.1%), 14(5.2%), 12 (4.4%), 6(2.2%), 2(0.7%), and 2(0.7%), respectively. Detection rates of Listeria spp. varied among four methods. The highest detection rate of Listeria spp. in market beef was found at USDA method and that of L. monocytogenes was found at Malthus method.

The inhibitory effects of vegetables, collected from Jinju district, on the growth of Listeria monocytogenes were investigated. Among 12 vegetables, garlic, leek, onion and cabbage were remarkably effective to inhibit the growth of the strain. Especially with the addition of extract equivalent 0.25 g of raw garlic per ml broth, the population of the strain was decreased significantly, and completely inhibited with the addition of 0.625 g or more. During the incubation with the addition of extract equivalent 0.25 g of raw garlic per ml broth, the degree of inhibition was gradually increased with the lapse of time, and completely inhibited the growth of the strain after 48 hrs. While the pH value of treated broth remained unchanged almost, those of control were slightly reduced.