All foods are not created equal. Most are palatable， or tasty to eat， which is important because people need to eat to survive. For example， a fresh apple is palatable to most people and provides vital nutrients and calories.

But certain foods， such as pizza， potato chips and chocolate chip cookies， are almost irresistible. Theyre always in demand at parties， and theyre easy to keep eating， even when we are full. In these foods， a synergy between key ingredients can create an artificially enhanced palatability experience. Researchers call this hyper-palatability. Eaters call it delicious.

Initial studies suggest that foods with two or more key ingredients linked to palatability—specifically， sugar， salt， fat or carbohydrates—can activate brain-reward neurocircuits similarly to drugs like cocaine or opioids. They may also be able to bypass mechanisms in human bodies that make people feel full and tell people to stop eating.

According to a study published by nutritional scientist Debra Sullivan， she identifies three clusters of key ingredients that can make foods hyper-palatable. It is estimated that nearly two-thirds of foods widely consumed in the US fall into at least one of those three groups. Foods that are easily accessible and cheap are everywhere in our society. Unsurprisingly， eating them has been associated with obesity.

Documentaries in the last 15—20 years have reported that food companies have developed formulas to make palatable foods so enticing. However， manufacturers typically guard their recipes as trade secrets， so academic scientists cant study them. Instead， researchers have used descriptive definitions to capture what makes some foods hyper-palatable.

In his 2012 book， David Kessler， former Commissioner of the US Food and Drug Administration （FDA）， wrote： “What are these foods？ Some are sweetened drinks， cookies， candy and other snack foods. Then， of course， there are fast food meals—fried chicken， pizza， burgers， and fries.”

并非所有食物都是生來平等的。大多數(shù)食物都美味可口，這一點(diǎn)十分重要，因?yàn)槿诵枰詵|西才能活下去。例如，對(duì)于大多數(shù)人而言，一個(gè)新鮮的蘋果不僅汁多味美，而且還能提供重要的營養(yǎng)素和卡路里。

但某些食物，例如披薩、薯片和巧克力曲奇餅干，卻令人無法抗拒。人們?cè)诰蹠?huì)時(shí)總能看到它們的身影，而且即便在已經(jīng)吃撐的情況下，也還能再吃一點(diǎn)。在這些食物中，主要調(diào)味成分間的協(xié)同作用可創(chuàng)造出一種人為增強(qiáng)的美味口感。研究員將其稱為超級(jí)美味性，食用者稱其為美味可口。

初步研究表明，含有兩種或多種主要調(diào)味成分（特別是糖、鹽、脂肪或碳水化合物）的食物可激活大腦的獎(jiǎng)勵(lì)神經(jīng)回路（與可卡因或阿片類藥物的作用類似）。這些食物或許還能避開人們的身體機(jī)制，而這種機(jī)制會(huì)提醒人們飽腹，不需要再度進(jìn)食。

營養(yǎng)學(xué)家黛布拉·沙利文發(fā)表的一項(xiàng)研究發(fā)現(xiàn)使食物變得超級(jí)美味有三類主要調(diào)味成分。據(jù)估計(jì)，美國接近三分之二的暢銷食品都至少含有這三類成分中的一種。便宜且易買的食物到處都是，食用這些食物而導(dǎo)致肥胖也就不足為奇了。

過去15至20年的紀(jì)錄片報(bào)道，食品公司已研發(fā)出使美味食品變得誘人的配方。但在通常情況下，食品生產(chǎn)商會(huì)將這些配方視作商業(yè)機(jī)密加以保護(hù)，所以學(xué)術(shù)專家無法對(duì)其展開研究。因而，研究員根據(jù)描述性的術(shù)語來探究某些食品口感極好的原因。

美國食品和藥物管理局前專員戴維·凱斯勒在其2012年發(fā)表的著作中寫道：“哪些食物屬于這一范疇呢？其中包括含糖飲料、餅干、糖果和其他休閑食品。當(dāng)然，快餐食品——炸雞、披薩、漢堡和炸薯?xiàng)l也屬于這類食物?！?/p>

Word Study

palatable /'p?l?t?bl/ adj. 可口的;味美的

synergy /'s?n?d?i/ n. 協(xié)同作用

ingredient /?n'ɡri?di?nt/ n. 成分;（尤指烹飪）原料

enhance /?n'hɑ?ns/ v. 提高;增強(qiáng)

This is an opportunity to enhance the reputation of the company.

bypass /'ba?pɑ?s/ v. 繞過;避開

A new road now bypasses the town.

estimate /'est?me?t/ v. 估算

The deal is estimated to be worth around $1.5 million.

formula /'f??mj?l?/ n. 配方