在线观看亚洲精品专区-在线观看亚洲免费-在线观看亚洲免费视频-在线观看亚洲欧美-欧美freexxx-欧美free嫩交video

食品伙伴網服務號
 
 
當前位置: 首頁 » 專業英語 » 專業知識 » 正文

How does food become contaminated?

放大字體  縮小字體 發布日期:2007-09-13
核心提示:We live in a world that has a wide diversity of microorganisms, and there are many opportunities for food to become contaminated as it is produced and prepared. Many foodborne microbes are present in healthy animals (usually in their intestines) rai

We live in a world that has a wide diversity of microorganisms, and there are many opportunities for food to become contaminated as it is produced and prepared. Many foodborne microbes are present in healthy animals (usually in their intestines) raised for food. Meat and poultry carcasses can become contaminated during slaughter by contact with small amounts of intestinal contents. Similarly, fresh fruits and vegetables can be contaminated if they are washed or irrigated with water that is contaminated with animal manure or human sewage. Some types of Salmonella can infect a hen's ovary so that the internal contents of a normal-looking egg can be contaminated with Salmonella even before the shell in formed. Oysters and other filter-feeding shellfish can concentrate Vibrio bacteria that are naturally present in seawater, or other microbes that are present in human sewage dumped into the sea.

  Later in food processing, other foodborne microbes can be introduced from the environment of food processing lines. They may also be introduced by infected humans who handle the food, or by cross-contamination from raw products. The unwashed hands of food handlers who are infected can introduce for example, Shigella bacteria, hepatitis A virus and Norwalk virus. In the kitchen, microbes can be transferred from one food to another food by using the same knife, cutting board or other utensil to prepare both without washing the surface or utensil in between. A food that is fully cooked can become recontaminated if it comes into contact with other raw foods or drippings from raw foods that contain pathogens.

  The way that food is handled after it is contaminated can also make a difference in whether or not an outbreak occurs. Many bacteria need to multiply to a larger number before enough are present in food to cause disease. Given warm moist conditions and an ample supply of nutrients, one bacterium that reproduces by dividing itself every half hour can produce 16 billion progeny in 12 hours. As a result, lightly contaminated food left out overnight can be highly infectious by the next day. On the other hand, if the food were refrigerated promptly, the bacteria would not multiply at all. In general, refrigeration or freezing prevents virtually all bacteria from growing but generally preserves them in a state of suspended animation. This general rule has a few surprising exceptions. Two foodborne bacteria, Listeria monocytogenes and Yersinia enterocolitica can actually grow at refrigerator temperatures. High salt, high sugar or high acid levels keep bacteria from growing, which is why salted meats, jam, and pickled vegetables are traditional preserved foods.

  Microbes are killed by heat. If food is heated to an internal temperature above 78°C for even a few seconds, it is sufficient to kill parasites, viruses or bacteria, except for the Bacillus and Clostridium bacteria, which produce a heat-resistant form called a spore. These spores are killed only at temperatures above boiling. This is why canned foods must be cooked to a high temperature under pressure as part of the canning process.

  The toxins produced by bacteria vary in their sensitivity to heat. The staphylococcal toxin, which causes vomiting, is not inactivated even if it is boiled. Fortunately, the potent toxin that causes botulism is completely inactivated by boiling.

更多翻譯詳細信息請點擊:http://www.trans1.cn
 
關鍵詞: food contaminated
[ 網刊訂閱 ]  [ 專業英語搜索 ]  [ ]  [ 告訴好友 ]  [ 打印本文 ]  [ 關閉窗口 ] [ 返回頂部 ]
分享:

 

 
推薦圖文
推薦專業英語
點擊排行
 
 
Processed in 4.269 second(s), 875 queries, Memory 3.45 M
主站蜘蛛池模板: 复古毛片 | 九九精品免费观看在线 | 国产精品成人va在线观看入口 | 日本不卡视频一区二区 | 手机看片福利视频 | 午夜一级毛片免费视频 | 四虎网址最新 | 伊人小婷婷色香综合缴缴情 | 国产色妞妞在线视频免费播放 | 亚洲色图欧美在线 | 91精品久久久久含羞草 | 视频在线观看免费视频 | 免费艹逼视频 | 四虎美女| 天天射天天草 | 日本a级特黄三级三级三级 日本边添边爱边摸边做边爱 | 中国业余老太性视频 | 天天做天天爱夜夜大爽完整 | 国产成在线人视频免费视频 | 91精品日本久久久久久牛牛 | 在线观看精品国产福利片100 | 被公侵犯肉体中文字幕一区二区 | 在线观看免费视频片 | 午夜视频在线观看免费观看在线观看 | 老师下面好紧 | 亚洲九色 | 爱情社保片鲁丝片一区 | 你懂的在线免费视频 | 国卡一卡二卡三免费网站 | 亚洲人成电影院 | 韩国理论三级在线观看视频 | 天天摸夜夜添夜夜添国产 | 四虎东方va私人影库在线观看 | 久久婷婷色综合老司机 | 久久久国产精品免费看 | 苦瓜se影院在线视频网站 | 天天干夜夜躁 | 风流护士| 午夜嘿嘿嘿| 狠狠五月深爱婷婷网免费 | 天堂69亚洲精品中文字幕 |