Listeria monocytogenes is a bacterium that causes listeriosis, a disease that can have severe consequences for particular groups of the population. It can cause miscarriages in pregnant women and be fatal in immunocompromised individuals and the elderly. In healthy people, listeriosis generally only causes a mild form of illness. L. monocytogenes can be found throughout the environment. It has been isolated from domestic and wild animals, birds, soil, vegetation, fodder, water and from floors, drains and wet areas of food processing factories.
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The growth and survival of L. monocytogenes is influenced by a variety of factors.In food these include temperature, pH, water activity, salt and the presence of preservatives.
The temperature range for growth of L. monocytogenes is between -1.5 and 45°C, with the optimal temperature being 30–37°C.
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Temperatures above 50°C are lethal to L. monocytogenes.
Freezing can also lead to a reduction in L. monocytogenes numbers
Even if L. monocytogenes is absent in ready-to-eat meat and poultry products after processing, or found at very low prevalence and levels, additional contamination can occur after the packs are opened - especially when the meat is handled.
Although L. monocytogenes can grow while refrigerated, growth is very slow at temperatures below 4ºC. In ready-to-eat foods stored at higher temperatures, for example above 7ºC, growth occurs more rapidly, increasing the risk that L. monocytogenes will reach levels more likely to cause human illness. Both safe food handling and maintaining proper refrigeration temperatures are critical to minimizing the risk of listeriosis.
COOKED MEAT – Listeria is killed by cooking. Thoroughly cooking product to 165ºF/74ºC will kill the bacteria. Consumers at high risk for contracting listeriosis (e.g. pregnant women and the elderly) should reheat deli meats immediately before consumption.
FREEZING – Listeria is not killed by freezing. Growth is arrested altogether, but normal growth will be resumed after thawing.
Edited by Charles.C, 03 March 2020 - 06:53 AM.