Food Poisoning -- and How to Pr It
Changing lifestyles in the modem world have resulted in an increased demand for ready-to-cat foods, fast foods and dining out. This change in demand has, in mm, brought with it new and increased problems. One of these is the risk of bacterial food poisoning.
How does food poisoning occur Usually, it takes large numbers of food poisoning bacteria to be present in food in order to cause illness. However, given the right conditions, bacteria can multiply very rapidly. These conditions include:
Time -- In ideal conditions, one bacterium can multiply to 2,097,152 within seven hours.
Temperature -- Food poisoning bacteria grow best in the temperature range of 5℃ -- 60℃.
This is called the temperature er zone. Food should not be left in the temperature er zone.
Nutrients -- Bacteria need their own food source to grow and multiply. The types of foods which bacteria prefer include dairy products, egg products, meat and poultry, small goods, not including salami (意大利腊肠), processed meat and chicken products, fish, shellfish and fish products.
Because bacteria multiply rapidly in these foods, they are known as high risk foods. High risk foods which have been contaminated (污染) with food poisoning bacteria and then left in the temperature er zone can cause food poisoning to anyone who consumes them.
Water -- Without moisture, the growth of bacteria slows down and may stop. Drying is an effective form of food preserving.
How does food become contaminated Food is contaminated through poor handling and storage and through lack of personal hygiene (卫生学) by the people who prepare and serve it. Food poisoning bacteria are very widespread. They can be found in the soil, on animals and on people. Because of this, it is possible for foods such as raw meat, poultry and vegetables to contain these bacteria from the start. A common way that food can become contamination, is through cross contamination. This can occur in two ways: During food preparation, hands, utensils (器具) and equipment such as cutting boards can become contaminated with bacteria from raw food. If these utensils, equipment and hands are then used to prepare ready-to-eat or cooked food, without first being thoroughly washed, then this food can become contaminated with bacteria from the raw food. As this food is not cooked again before being consumed, the bacteria in it will not be killed by cooking.
During storage, bacteria from raw food can contaminate ready- to- eat or cooked food if the later are not stored separately. If they are stored in the same refrigerator, raw food should always be stored in the lowest part of the refrigerator and ready-to-eat or cooked food on the shelves above. This prs liquids from the raw food dripping on to the cooked food. Store food in clean non- toxic washable containers or cover with foil or plastic film.
How can food poisoning be pred Food poisoning can be pred by:
(1) Pring food from becoming contaminated.
(2) Pring the bacteria in the food growing and multiplying.
We can think of food poisoning as being a chain of circumstances:
·There must be bacteria on the food.
·The bacteria have the right conditions to grow-warmth ( between 5℃ and 60℃) , moisture and food.
·The bacteria have time to grow and multiply.
If this chain of s can be broken, food poisoning can be pred.
Some of the ways of breaking this chain are:
· sure your hands are dean before handing food.
·Thoroughly washing all equipment used for preparing raw foods.
·Storing raw foods below cooked foods in the refrigerator.
·Storing food correctly -- not in the Temperature er Zone.
· sure food is served as soon as possible after preparation.
Some Common Food Poisoning Bacteria
Salmonella (沙门氏菌)
Commonly found in: meat, poultry, eggs and egg products.
Symptoms: nausea (恶心), stomach cramps, diarrhea (痢疾), fever and headache.
Onset(发作): 6 -- 72 hours after consuming contaminated food. Symptoms can last from 3--5 days.
Bacillus (杆状菌)
Commonly found in: Cereals, rice, meat products, packet soups.
Symptoms: nausea, vomiting, diarrhea and stomach cramps.
Onset: 1--6 hours after consuming the contaminated food. Symptoms usually last no longer than 24 hours.
Note: These bacteria produce spores which are not killed during cooking. When cooked food containing these spores, has been left in the temperature er zone, the spores produce toxins (poisons) in the food which can cause food poisoning.
Staphylococcus aureus
Commonly found in: Meat and poultry dishes, egg products mayonnaise-based salads, cream or custard filled desserts.
Symptoms: acute vomiting, nausea, occasionally diarrhea and cramps.
Onset: 30 minutes -- 8 hours after consuming the contaminated food. Symptoms usually last about 24 hours.
Note: These bacteria produce toxins in food. The toxin is not destroyed during cooking so correct storage of food before and after cooking is essential. These bacteria are commonly found on the skin and in the nose and mouths of healthy people.
Therefore, it is important that you maintain high standards of personal hygiene (卫生学) when working with food. People with open cuts or wounds on their hands and arms must ensure that the injury is completely protected by a waterproof bandage.
Other common food poisoning bacteria include:
·Clostridium perfringens.
·Vibrio parahaemolyticus.
·Listeria monocytogenes. Nowadays, people’s lifestyles are changing, which has resulted in the demand for fast foods.