日常生活所需的食物如魚类、肉类、蛋类、水果、蔬菜等等,往往需要加以保存。但是,放不多久就会腐敗变质。这是由于食品本身的酶和微生物活动造成的。为了保存这些食品,人們采用了盐漬、干制、熏煮、罐藏、蜜餞等方法。但是这又会使食品的色、香、味和营养价值受到不同程度的影响,而且这些方法都不能把大量食品长期保 The foods needed for daily life such as fish, meat, eggs, fruits, vegetables, etc., often need to be preserved. However, it will not be long before the corruption deteriorates. This is due to the enzymes and microbial activity of the food itself. In order to preserve these foods, people used salted, dried, smoked, potted, candied and other methods. However, this will affect the color, aroma, taste and nutritional value of foods to varying degrees, and these methods cannot guarantee long-term preservation of large quantities of foods.