![]() The lowest recorded temperature for the growth of pathogenic bacteria is -2☌ and although pathogens can survive freezing they do not multiply. Some pathogens will grown between 0☌ and 20☌ but they multiply more slowly at the lower temperatures. The range of temperature, which is likely to encourage the fastest multiplication, is between 20☌ and 50☌. However, many can survive outside this temperature range and start multiplying again when temperatures are suitable. ![]() The common food po isoning bacteria will not multiply below 5☌ or above 52☌. Most food poisoning bacteria grow best at around 37 ✬ (body temperature) although clostridium perfringens prefers 46 ☌. ![]() For this reason we must protect acid food from contamination at all times.īacteria have a maximum and minimum temperature for multiplication as well as an optimum temperature when multiplication is the most rapid. However, if a large number of food poisoning bacteria are introduced into an acid food it may take some time for the bacteria to die. Most bacteria will not multiply in pH below 4.0, i.e. The pH of a food is measured on a scale of 1 to 14 (hydrogen ion concentration.) Acid foods have pH values below 7, alkaline foods about 7 and a pH value of 7 is neutral. How ever, some bacteria can survive dehydration and when liquid is added to the dried food it once again becomes a high-risk food and must be stored under refrigeration. With the expectation of dehydrated products such as milk powder, most foods contain sufficient moisture to enable bacteria to multiply. The water activity of food is the measure of the available water. Foods with high sugar and salt content are usually unsuitable and therefore are unlikely to support bacteria multiplication.īacteria required water to transport nutrient into the cell and take away waste products. which are usually provided high protein food such as meat, fish and dairy produce. The multiplication of pathogens in food is a hazard.įood poisoning bacteria obtain their essential basic nutrients from amino acids, fats, vitamins and minerals. This number of bacteria is likely to cause food poisoning. Is this food provides optimum conditions then within one hour 40 minutes, these bacteria could double every 10 minutes and become 1,000,000. ![]() If food is contaminated a common level of contamination may be around 1,000 bacteria per gram of food. When food bacteria are growing and multiplying this is described as the vegetative state. The average generation time of the common food poisoning bacteria under optimum conditions is usually considered to be around 20 minutes. In optimum (ideal) conditions some food poisoning bacteria can split in two every ten minutes, although at temperatures of around 10°c it may take up to ten hours or they may stop multiplying. This process is known as binary fission and the time taken between each division (generation time) varies considerably depending on, among other things, temperature and the nutrients (food) available. Bacteria reproduce by splitting into two. ![]()
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