Faking It in the Word of Fats and Sugars

　　在脂肪和糖的世界里作假

　　by Kathiann M. Kowalski

　　Shop in any supermarket, and you’ll find lots of sugar-free and fat-free foods. What’s in them, and how good for you are they?

　　Something Sweet

　　Sugar, corn syrup, honey, and other natural sweeteners stimulate certain receptors on your tongue. They send nerve messages that make your brain say, “Sweet!” However, the receptors can be “tricked” by other molecules.

　　Aspartame, known as NutraSweet, is made from two amino acids which normally serve as building blocks for proteins. While the body metabolizes (uses) it like protein, explains George Pauli at the Food and Drug Administration (FDA), “t just happens to bind to taste buds to give a sweet taste.” Also, Aspartame is 200 times sweeter than sugar, so people need to consume very little to get a sweet product.

　　Acesulfame K, or Sunett, combines potassium with acetoacetic acid. Saccharin, which has been around since 1879, is made from methyl anthranilate, a substance in grapes. The body doesn’t metabolize either compound.

　　On the other hand, sucralose, known as Splenda, is made from sucrose, or table sugar. Because chlorine atoms fill certain spots on the molecule, your body can’t digest it. It adds no calories, yet it’s 600 times sweeter than regular sugar.

　　Other sweeteners are undergoing FDA review. Natural sugar alcohols, such as sorbitol, sweeten foods, too.

　　Why so many sweeteners? Some have a longer shelf life. Others hold up better in baking. Variety lets food manufacturers choose which ingredient works best.

　　Fixing the Fat

　　Fat replacers come from carbohydrates, proteins, and even fats themselves. Carbohydrate-based replacers, such as dextrins and gums, provide the texture and flow properties of fat.

　　Protein-based replacers also aim to give the “mouth feel” of fat. One example is microparticulated protein, such as Simplesse. “It’s a whipped up protein and air product,” explains Pauli.

　　Olestra, or olean, is probably the best known replacer made from fat itself. It’s either soybean oil or cottonseed oil, combined with sucrose.

　　“Glycerol plus three fatty acids equals regular digestible fat,” explains Greg Allgood at olestra developer Procter & Gamble. “lestra is sugar plus eight fatty acids.” The configuration of that large molecule keeps digestive enzymes from attaching－a condition that chemists call stearic hindrance. As a result, olestra can’t be digested. It adds no calories or fat to chips or other salty snacks.

　　What About Safety?

　　Low-cal and low-fat foods sound too good to be true. Are their substitute ingredients safe?

　　Saccharin use began before 1958, when the FDA started requiring approvals for new food ingredients. Various groups, including the American Cancer Society and the American Dietetic Association, have said saccharin is acceptable when used reasonably.

　　For products that have gotten FDA approval, Pauli says, assume they’re okay. “pproval means that our scientists have concluded that there’s a reasonable certainty that no harm will result from the intended use of the food ingredient,” he explains.

　　Approval comes only after many animal and human tests. Olestra, for example, underwent over 150 studies with more than 20,000 people. Because some vitamins are fat-soluble, olestra foods are vitamin-fortified. The initial label advised that too much could cause more frequent bowel movements, just as too many beans or apples could, says Pauli. But since that wasn’t harmful, the label is “not a warning.” Based on later testing, a revised label will have less alarming language, note Pauli and Allgood.

　　Aspartame products warn that people with a rare genetic disease, phenylketonuria, cannot eat one of its ingredients. But scares about seizures, headaches, and other problems are unfounded, says the FDA. “There was a lot of follow-up testing done,” emphasizes Pauli.

　　No fake fat or sweetener is a “magic pill” for weight loss. Nor does safety make fat or sugar replacers a good choice for everyone. “Children need calories to grow. They need a certain amount of fat as an essential nutrient,” stresses Pauli. “Balance is the best approach. In other words, avoid extremes.”

　　Nonetheless, millions of Americans are overweight, and people with diabetes must restrict their sugar and fat intake. Safe replacement ingredients can help these people control their diets and make sound nutrition choices.

　　The Taste Test

　　Allgood says that he and his daughter love the taste of olestra snacks. “You can develop all the foods you want that have health benefits,” he explains, “but if they don’t taste good, people aren’t going to eat them.”

　　The same goes for all foods made with fat or sugar replacers. So, why not put your taste buds to work? Design a “blind” taste test for family and friends that compares one product containing a fat or sugar substitute with the “real thing.”

　　你在超市购物时会发现许多种不含糖和不含脂肪的食品。它们含有什么成分？对你到底有多少好处？

　　甜食

　　蔗糖、玉米糖、蜂蜜和其他天然含糖的物质会刺激你舌头上的某些接收器。接收器把神经信息发出去，令大脑作出反应，说：“真甜!”然而，这些接收器也会受其他分子的蒙骗。

　　阿斯巴特这种糖精又被人们称为人造甜味剂。它是由两个氨基分子构成，通常是构成蛋白质的成分。美国国家药品和食品管理局（FDA）的乔治·鲍力先生说：“尽管身体把它当作蛋白质来使用，它恰巧能刺激味蕾，给人一种甜味的感觉。”另外，这种糖精比蔗糖甜200倍。因此，当人们需要甜食的话，他们加很少一点的甜味剂就够了。

　　把钾和乙酰醋酸结合起来就构成了含钾盐的糖精，又称“桑奈特”。另外一种糖精在1879年就出现了。它是由葡萄中的一种含甲基的物质构成的。人体都不能吸收这两种化合物。

　　另一方面，被称为斯普兰达的蔗糖素是从蔗糖或食用糖中提炼出来的。因为氯离子填充了分子中的某些位置，你的身体也不能消化它。食用这种物质不会使人增加热量，但它的甜度却是普通蔗糖的600倍。

　　其他的甜味剂正在由美国国家药品和食品管理局进行审查。天然的蔗糖酒精，比如说葡萄糖醇，也会使食物变甜。

　　为什么有这么多甜味剂呢？有些甜味剂的保质期长。另外一些在烤制的食品中效果较好。这么多种甜味剂可以让食品生产商选择最好用的添加剂。

　　对付脂肪

　　脂肪的代用品来自碳水化合物、蛋白质甚至是脂肪本身。用碳水化合物制造的代用品，比如说糊精和口香糖，具有脂肪所固有的纹理和流动的特性。

　　用蛋白质制造的代用品同样也想在口感上接近脂肪，其中的一个例子就是像新普利斯一样的微粒蛋白质。鲍力解释说：“这是一种搅拌好的蛋白质和空气制品。”

　　奥利斯特拉油又被称为奥林，可能是最好的从脂肪本身提炼出来的脂肪代用品。它是豆油或棉花籽油同蔗糖结合而成的。

　　宝洁公司是奥利斯特拉油的开发商。该公司的格利戈·奥固德解释说：“甘油加上三种脂肪酸就会形成通常可消化的脂肪，而奥利斯特拉油是由蔗糖加上八种脂肪酸构成的。”那个大分子的结构使消化酶无法附着，化学家把这种状态称为硬脂阻隔。结果是，奥利斯特拉油不能被消化。这种油不会给炸薯条或其他纤维快餐增加热量或脂肪。

　　这些食品安全吗？

　　低热量和低脂肪的食物听起来好得令人难以置信。它们当中所含的配料安全吗？

　　人们在1958年以前就开始使用糖精。从那时起，FDA开始要求对新推出的食品配料进行审批。包括美国癌症协会和美国饮食协会在内的各类团体都说，如果糖精被合理使用的话，是可以接受的。

　　我们可以认为通过FDA检验的食品是没问题的。鲍力解释说：“食品通过检验意味着科学家们已经得出结论，可以比较肯定地说食用这些食品配料不会带来什么危害。”

　　只有经过多次在动物和人身上进行试验，才能通过审批，比如，奥利斯特拉油在超过20000人的身上进行过150多次研究。因为一些维生素会溶解在脂肪中，奥利斯特拉油会对维生素起到固定作用。鲍力说：“就像食用过多的豆子或苹果会导致大肠更加频繁地蠕动一样，这种商品最早的标签上也注明过多地食用这种油也会产生同样的结果。”但这对人体并没有什么危险，所以标签上的说明并不是“警告”。鲍力和奥固德注意到，经过随后的检验，这一标签上的文字被修改，用词上不那么扰乱人心了。

　　阿斯巴特糖精类产品对人们提出警告，说患有苯酮尿这种少见的遗传疾病的人不能食用其中的一种成分。FDA说，担心食用糖精会引起痉挛、头疼和其他问题是没有根据的。鲍力强调说：“已经做了很多后续的试验。”

　　假脂肪或甜味素并不是减肥的妙药。这些东西虽然是安全的，但并不意味着脂肪和蔗糖代用品对任何人来说都是最佳的选择。鲍力强调说：“儿童们成长中需要热量。一定量的脂肪也是他们必不可少的营养素。平衡的饮食是最佳的选择。换句话说，我们要避免走极端。”

　　尽管如此，上百万的美国人都体重超标。得了糖尿病的人必须限制自己对蔗糖和脂肪摄入。安全的代用品可以帮助这些人控制他们的饮食，并帮助他们作出正确的营养选择。

　　味觉试验

　　奥固德说他和女儿都喜欢含奥利斯特拉油的零食。他解释道：“你可以开发所有你所需要的健康食品。但如果它们味道不好，人们不会去吃的。”

　　添加了脂肪或蔗糖代用品的食品也是如此。所以，为什么不让你的味蕾发挥作用呢？为家人和朋友设计一次蒙上眼睛进行的味觉试验。比较一下含有脂肪和蔗糖代用品的食品与“真货”的区别。

　　Sweet Serendipity

　　Like other areas of science, food chemistry requires intelligence and hard work. However, luck plays a role, too.

　　G.D. Searle & Co.’s James Schlatter was researching ulcer medicines in 1965. When he licked his finger to grab a piece of paper, he noticed a sweet flavor. The taste turned out to be aspartame. (Warning: Never lick your fingers when you are working with chemicals!)

　　Also in the 1960s, Procter & Gamble’s Fred Mattson hoped to develop an energy-intense fat molecule to help feed premature infants with tiny stomachs. What he got was just the opposite: Olestra, a fat with no calories.

　　For more information:

　　http://www.fda.gov (Food and Drug Administration)

　　http://ificinfo.health.org (International Food Information Council)

　　http://www.caloriecontrol.org (Calorie Control Council)