2016年11月12日托福閱讀真題第三篇

　　題材劃分：社科類

　　主要內(nèi)容： 主要講食物是如何保存的，以前的食物保存方法是的食物口感很差，營養(yǎng)丟失。為了讓軍隊的人吃的好，法國政府搬出一個獎，獎勵發(fā)明出新事物保存方法的人，該方法要便宜，食物好運輸，好吃還要有營養(yǎng)。最開始是一個科學(xué)家做了一個真空實驗，了解到聲傳播需要空氣，于是推測食物保存也需要空氣，但實驗過后發(fā)現(xiàn)空氣并不是sole reason。然后第二人在這個基礎(chǔ)上用真空vessel之后又放在熱水里，發(fā)現(xiàn)能很好保存了。但是大家并不知道原理是什么，只能猜測是something導(dǎo)致了變質(zhì)。最后得到獎金的是一個廚師，他爸爸是個manager，在廚房工作的時候發(fā)現(xiàn)大家都是用糖來保存水果，于是就想到怎樣保存食物，然后的方法與之前不同在加熱后封好迅速冷卻。

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　　相關(guān)知識背景：

　　Food preservation involves preventing the growth of bacteria, fungi (such as yeasts), or other micro-organisms (although some methods work by introducing benign bacteria or fungi to the food), as well as slowing the oxidation of fats that cause rancidity. Food preservation may also include processes that inhibit visual deterioration, such as the enzymatic browning reaction in apples after they are cut during food preparation.

　　Many processes designed to preserve food will involve a number of food preservation methods. Preserving fruit by turning it into jam, for example, involves boiling (to reduce the fruit’s moisture content and to kill bacteria, etc.), sugaring (to prevent their re-growth) and sealing within an airtight jar (to prevent recontamination). Some traditional methods of preserving food have been shown to have a lower energy input and carbon footprint, when compared to modern methods.

　　Some methods of food preservation are known to create carcinogens. In 2015, the International Agency for Research on Cancer of the World Health Organization classified processed meat, i.e. meat that has undergone salting, curing, fermenting, and smoking, as "carcinogenic to humans".

　　Maintaining or creating nutritional value, texture and flavor is an important aspect of food preservation, although, historically, some methods drastically altered the character of the food being preserved. In many cases these changes have come to be seen as desirable qualities cheese, yogurt and pickled onions being common examples.