So that food can be "fresh" when it is on the shelves, agricultural products must be harvested before they are mature. Then in each stage of shipping and processing, given that there are many opportunities for exposure to bacteria, the food must be kept in cold storage, or subjected to chemicals or radioactivity to preserve "freshness."
為了讓食物趁鮮上市、更有賣相，農產品必須在未成熟前提早採摘，之後的層層運輸處理過程中，又有很多機會暴露在細菌下，必須以低溫冷藏、各種化學藥劑或放射線來保持鮮度。