Conference paper
The importance of test results Listeria monocytogenes in milk and milk products
Branka Magdalenić
; Prehrambeno-biotehnološki fakultet, Pierottijeva 6, 10000 Zagreb
Abstract
Listeria monocytogenes was first described in detail by Murray in 1926. when bacterium was isolated from rabbits. The bacterium is gram-positive, asporogenous and rod-shaped. It grows at 1 to 4 °C, its optimum of growth being at 30-37 °C. It can grow at pH values ranging from 5,0 to 9,0. L. monocytogenes is aerobic to facultatively anaerobic and pathogenic to humans and animals. The incidence of listeriosis is caused by Listeria monocytogenes. Infection of pregnant women with L. monocytogenes can lead to transplacental infection of the fetus. Earlier infection may cause damage to the embryo, so in some instances abortion or stillbirth occured immediately. This bacterium can cause encephalitis, mastitis and abortion in dairy cattle. Although L. monocytogenes has been known as a human and animal pathogen for over 50 years, the potentially important role of this organism as a food-borne pathogen has only surfaced in the 1980. The number of listeria food poisoning cases is small and very low compared to other forms of food poisoning, but the mortality rate is higher (30%). The number of reported cases of listeriosis is increasing during the last decades. L. monocytogenes has been isolated from milk, cheese, meat, fish and vegetables. In contrast to most of other pathogenic bacteria, L. monocytogenes is able to grow at refrigeration temperatures, and seems to be more thermoresistant than other nonsporulating food poisoning bacteria. This paper deals with the behavior of L. monocytogenes in fluid milk products, fermented dairy products, cheeses, and other dairy products. These bacteria survive in different kinds of cheese and grow in cheese. The behavior of the pathogen in cheese depends mainly on the strain of L. monocytogenes and on different conditions of cheese manufacturing, ripening and storage. The importance of prompt and reliable detection of L. monocytogenes in milk and milk products is connected to possible consequences for consumer. One significant point in evaluation of good quality raw milk and milk products is the investigation assigned to prove the presence of L. monocytogenes. The use of appropriate hygienic procedures during the milk processing should reduce the likelihood of listeriosis outbreaks associated with dairy foods.
Keywords
Listeria monocytogenes in milk; food poisoning; L. monocytogenes in fluid milk, fermented milk, cheese and other dairy products; survival of L. monocytogenes in dairy products; proving the presence of L. monocytogenes
Hrčak ID:
95281
URI
Publication date:
17.1.1993.
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