a国产亚洲欧美精品一区在线观看_看一级黄色毛片_在线观看播放_一级片精品_国产精成人品日日拍夜夜免费_草久在线视频

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: 日欧137片内射在线视频播放 | 国产日产欧产精品浪潮的隐私保护 | 精品国产18久久久久久洗澡 | 人人性人人性碰国产 | 日本免费一区二区三区四区 | 一级做a爰性色毛片免费1 | 日本乱码伦视频免费播放 | 国产剧情息子绝伦中文字幕 | 三及片毛片| 国产亚?欧美一区二区 | 2021久久超碰国产精品最新 | 欧美成人精品一区二区 | 免费无码国产欧美久久18 | 久久夜色精品亚洲噜噜国产mv | 国产黄色播放 | 草蹓视频在线观看 | 天天爱夜夜操 | 亚洲无吗一区二区三区 | 婷婷综合亚洲爱久久 | heyzo朝桐光一区二区 | 欧美劲爆婷婷五月久久 | 国产精品一区二区久久精品爱微奶 | 污污汅18禁在线无遮挡免费观看 | 91在线精品 | 国产国产美女裸身网站免费观看视频 | www片香蕉内射在线88av8 | 夜夜干av | 成在人线AV无码免费 | 国产蜜臀一区二区打屁股调教 | 日韩中文字幕专区 | 乱子伦xxxxvideos| 亚洲第一极品精品无码 | 亚洲AV永久无码天堂网毛片 | 综合国产视频 | 久久国产经典视频 | 99综合精品| 99视频热| 四月是你的谎言免费观看动漫 | 国产成人精品a视频一区www | 国产成人精品优优AV | 美女网色 |