時(shí)差N小時(shí):果膠是什么 What is jello?

It's pretty easy to guess what most of your food ismade of. The meat in your hamburger probablycame from a cow, the bun was made from grain, theketchup from tomatoes, and so on. There is one kindof food, however, that might have you guessinganimal, vegetable or mineral for the whole meal.But no more, since we'll learn about Jello on today'sMoment of Science.

要猜出大多數(shù)食物是由什么做成的十分簡(jiǎn)單。漢堡里的肉可能來自于牛，小圓面包可能來自谷物，番茄醬由西紅柿做成，等等。然而有一種食物就不容易猜了，到底它是來自于植物、動(dòng)物還是礦物質(zhì)呢?沒關(guān)系，學(xué)了今日科學(xué)時(shí)刻關(guān)于果膠的知識(shí)后，你就不會(huì)再感到迷惑了。

Jello is a trademark name for gelatin, a food that people have enjoyed for generations. Toanswer the question animal, vegetable, or mineral: gelatin is an animal product. It is preparedby soaking the bones, skin, or connective tissue from pigs or cows in a bath of mildhydrochloric acid solution. After this, the animal products are heated in distilled water formany hours, and finally boiled. The fluid that collects from this process is drawn off.

果膠是明膠的商業(yè)用名，是一種幾代人都享用過的食物。從植物、動(dòng)物或者礦物質(zhì)中選擇一個(gè)來回答這個(gè)問題的話，那就是動(dòng)物。果膠的制作方法是，用輕度的鹽酸溶液浸泡?；蛘哓i的骨頭，皮肉或者結(jié)締組織;之后用蒸餾水加熱幾個(gè)小時(shí)直至沸騰;在這個(gè)過程中收集流出來的液體。

What's left is dried, and ground into a fine, pale yellow powder. This is unflavored gelatin, thebasis of all gelatin salads, desserts, and drinks. Gelatin is valuable as a food because it is pureprotein and it is easy to digest. A gelatin made from vegetable protein, called agar-agar, ismade for vegetarians. When powdered gelatin is stirred into hot water and then chilled, it formsthe jiggly, gelled product that we are most familiar with. This gelled product is not strictly asolid or a liquid.

把最后剩下的部分晾干，磨成細(xì)小，微黃的粉末。這粉末就是無味的明膠，所有明膠色拉，甜點(diǎn)和飲料的原材料。明膠與天然食物的營(yíng)養(yǎng)價(jià)值相同，因?yàn)樗怯杉兊鞍踪|(zhì)組成，并且很好消化。用植物做成的明膠叫做瓊脂。瓊脂是為素食主義者準(zhǔn)備的。當(dāng)把粉末狀明膠混合開水?dāng)嚢?，然后冷卻，就會(huì)形成我們非常熟悉的不穩(wěn)定的、稠化的食品。嚴(yán)格來講，這種食物既不是固體也不是液體。

Technically it's a colloid: a liquid suspended in a solid framework. As the hot mixture coolsoff, the long strands of animal protein lock together into a solid framework, trapping tinydroplets of liquid water in the process. It's these droplets of water, trapped in a mesh of animalprotein, that hold all the coloring and flavoring in your favorite gelatin dessert.

學(xué)術(shù)上來說它是膠體：一種液體懸浮在另一種固體中。當(dāng)熱的混合物冷卻后，長(zhǎng)長(zhǎng)的動(dòng)物蛋白鏈就會(huì)凝聚成一塊固體，并在凝聚過程中吸附微小的液態(tài)水滴。正是這些水滴鎖住了所有的顏色和味道，所以你才能吃上色香味俱全的果膠甜點(diǎn)。