您现在的位置: 纽约时报中英文网 >> 纽约时报中英文版 >> 科学 >> 正文

微波炉预制餐难吃的真正原因

更新时间:2018-3-8 19:49:03 来源:纽约时报中文网 作者:佚名

The secrets tricks in our microwave meals
微波炉预制餐难吃的真正原因

On the label it simply said “Value Vegetable Lasagne”. But from the picture on the box, I could see that the manufacturer was being modest. This was going to be a carnival of flavour, with a delectably rich sauce, layers of silky pasta, a light-yet-creamy bechamel topping and the savoury tang of crispy melted cheese.

包装标签上只是简单地标着"优质蔬菜意式千层面"(Value Vegetable Lasagne),但从盒子上的图片看,这家食品企业实在是太低调谦虚了。这道美食搭配着令人赏心悦目的丰富酱料,有好几层奶酪面饼、淡奶油盖料和可口的酥脆奶酪皮。

I dutifully removed the cardboard sleeve, stabbed the film lid and set it in the microwave. Two minutes later, however, the dish that slopped onto my plate was unrecognisable. The cheese had liquefied into an oily slick, the bechamel had congealed and the pasta was as rubbery as overcooked calamari.

我仔细地拆掉纸盒包装,把塑料薄膜戳破,然后放进微波炉。两分钟之后,我把它移进我的盘子。不过现在它和包装图片毫无相似之处:奶酪融化成了一层油腻的浮油,奶油盖料凝固了,面饼就像煮过头的鱿鱼一样根本嚼不动。

We’ve all had one: the barely edible microwaveable ready meal. They might be ready in minutes, but crafting a recipe that works is an onerous process – one that requires a surprising amount of science. At the high end of the scale, this includes elegant techniques pioneered in Michelin-starred restaurants; at the other, plenty of E numbers.

这就是我们每个人都有过的经历:难以下咽的微波炉速食食品。它们虽然在两三分钟就能做好,但却要去模仿要经过复杂工序才能制备的美食,这显然需要大量高科技才能做到。微波炉速食食品包罗万象,高级的有米其林星级餐厅里的复杂料理,普通的只不过是各种基本营养物质的机械组合。

To understand why, it helps to get to grips with the queen of chemical reactions, the Maillard reaction. First discovered by the French chemist, Louis-Camille Maillard, back in 1912, it’s the most widely practiced chemical reaction on the planet. It happens in millions of kitchens every day, though very few people have heard of it.

要想知道背后原因,就必须了解"化学反应之王"——美拉德(Maillard)反应。美拉德反应最早由法国化学家路易-卡米拉·美拉德(Louis-Camille Maillard)于1912年发现,是地球上最常见的化学反应。尽管美拉德反应每天都会在千家万户的厨房里发生,但却很少有人听说过它。

Essentially, something delicious happens when you mix amino acids with certain kinds of sugars, then heat them up. New compounds begin to form, which turn the food brown and contribute to its flavour.

美拉德反应指的是当你把氨基酸和某些种类的糖分混合并加热后,就会形成美味的反应产物。化学反应会形成新的化合物,将原料变为褐色并使之美味可口。

These Maillard by-products are responsible for the earthy sweetness of coffee and the malty, caramel notes in beer, as well as the appetising aroma of baked bread, chips, fried onions, barbecued meat, biscuits, toasted marshmallows, and most other foods that we find irresistible. It’s one reason spices are fried or toasted before they’re used, and why there’s no comparison between roasted and boiled potatoes. Our attraction to them might be innately human, since they’re a by-product of cooking and we’re the only species that can do this (though with some prompting, chimpanzees are getting close, scientists reported in 2015).

上述美拉德反应副产物就是咖啡略带土腥的甜味、啤酒的麦芽清香、以及烘焙面包、薯片、炸洋葱圈、烤肉、饼干、烤棉花糖以及我们无法抗拒的种种美食散发出令人垂涎的香味的原因。出于同样原因,香辛料在使用前要油炸或烘烤,煮土豆的味道远不如烤土豆香味扑鼻。它们都是高温烹调的产物,而人类是唯一一种吃熟食的生物(尽管2015年有科学报告称,某些黑猩猩也吃熟食),因此品鉴美食的天赋可能为人类所独有。

“It’s a very complicated reaction,” says Steve Elmore, a flavour chemist at the University of Reading. Depending on the proteins and sugars involved, there are thousands of possible by-products. Amino acids with higher levels of nitrogen tend to lead to more nutty smells, while the more potent varieties, according to Elmore, tend to involve sulphur and smell of onions.

"这是一种非常复杂的反应,"雷丁大学(University of Reading)食品化学家史蒂夫·埃尔默(Steve Elmore)说。根据参与反应的蛋白质和糖类不同,美拉德反应会产生成千上万种反应副产物。含氮量较高的氨基酸会发出坚果气味,而据埃尔默说,含硫的高烈性物质则会释放洋葱气味。

The problem is, the reaction can’t happen if the food is too wet. “If you’ve got a raw potato in the oven, it’s got around 80% moisture,” says Elmore. Once it gets to boiling point, water starts to evaporate and its surface begins to dry. “You need to get the water content down to about 5% before the Maillard reaction will take place and you get all the nice cooked flavours and brown colour.” This is why roast potatoes are usually brown on the outside and white on the inside.

问题在于,如果食物原料含水量高,就不会发生美拉德反应。"你要是把鲜番茄放进烤箱,只会把烤箱中的空气湿度增加到80%,"埃尔默表示。食物中的水分一旦达到沸点就会蒸发,使食物表面干燥。"只有含水量低于5%的食物才会发生美拉德反应,你才能得到口感美味、颜色焦黄的成品。"这就是烤土豆为什么外皮发黄,而内部却呈现白色的原因。

Microwaves work differently. Rather than heating the surrounding air, they bombard food with tiny, high-powered radio waves that heat up the molecules inside as they pass through. This relatively even cooking means the surface never gets hot or dry enough for the Maillard reaction to occur, leading to disappointingly pallid toppings on shepherd’s pies and lasagnes.

微波炉的原理则与之不同。它不是先加热食物周围的空气,而是用高能微波加热食物内部的分子。在这种较为均匀的加热方式下,食物表面无法达到发生美拉德反应的高温和干燥。在这种条件下,土豆泥肉馅饼或意式千层面不再有酥脆的外皮,从而失去了特有的风味。

This also means that ready meals tend to taste a bit bland. One early study found that beef cooked in the microwave had just a third of the scrumptious aromatic chemicals of meat that was cooked conventionally, while another found that microwave-baked bread was, frankly, disgusting.

由此,速食食品的口味一般都寡淡无奇。一项早期研究发现,与采用传统烹调方式相比,在微波炉中煮熟的牛肉中,决定牛肉口感的芳香化学物质含量只有传统烹调方式的三分之一。其他研究则发现,采用微波炉烹调的牛排味道令人作呕。

Less scrupulous manufacturers attempt to mask the lack of delicious browning by loading their products with salt, sugar and monosodium glutamate (MSG), which gives food a savoury taste and is reputedly abundant in Chinese takeaways. Back in 2015, a joint investigation by The Telegraph newspaper and campaign group Action on Sugar found that some British supermarket meals contained twice as much sugar as a can of Coca-Cola, or around 13 teaspoons (that’s four teaspoons more than the recommended daily amount for an adult male).

为了改善外观和口味,某些食品企业会在速食食物中预先加入盐、糖和谷氨酸钠以增加食物的鲜度。这种做法在中餐外卖中很普遍。2015年,《电讯报》(Telegraph)和市场营销企业Action on Sugar联合开展了一项调查。调查发现,某些英国超市食品含有的糖分比一罐可口可乐多一倍,多达13茶勺(比成年男性每天建议食糖量多4茶勺)。

But it doesn’t have to be this way. As the demand for meals with a fresh, homemade flavour grows, manufacturers are beginning to take a more sophisticated approach. And this starts with choosing the right ingredients. “The reality is, not everything is suitable for cooking in a microwave,” says Benn Hodges, the head chef at Eat First, a company specialising in gourmet ready meals. He’s worked at some of the best restaurants in the world, including the Michelin-starred branch of Roka in London.

这并非唯一的解决方案。随着新鲜天然食品的需求量不断上升,食品企业开始采取更为复杂的技术。首先是选择适当的配料。"并非所有配料都适合用微波炉烹制,"高档速食食品企业Eat First公司首席厨师本·霍吉斯(Benn Hodges)说。他曾经在多家世界顶级餐厅工作,其中包括获得米其林星级的Roka餐厅英国伦敦分店。

Take salmon. The striations on individual fillets are where the separate muscles used for swimming join up. They’re stuck together with collagen, which melts and turns to gelatine as it cooks – this is why fish turns flaky. At the same time, proteins in the muscle begin to denature and coagulate – this is why it turns opaque.

以三文鱼为例。三文鱼片上的纹路是三文鱼用来游泳的肌肉依次排列而成。这些肌肉由胶原蛋白粘在一起,而在高温烹调时,胶原蛋白会融化并转化为明胶物质,这就是三文鱼块在高温下会碎掉的原因。与此同时,肌肉中的蛋白质开始变性并结块,从而使三文鱼失去原本鲜亮透明的质感。

As all good cooks will know, the main dangers with salmon are that it will fall apart, and that shrinking muscle fibres will squeeze out moisture, turning your previously juicy dinner into a dry mess. The best way to avoid both is to get it as hot as possible and cook it fast, and this is where microwaves come in.

所有厨师都知道,做三文鱼最大的风险就在于它会碎掉,同时肌肉纤维在收缩后会挤出水分,从而把原本多汁的鱼肉变成一团干巴巴的肉。防止上述两种现象出现的方法在于:用高温快速烹制三文鱼肉。这种情况下,微波炉正好能大显神威。

Most microwaves use a wave frequency of 2.45 gigahertz, which is most easily absorbed by water, fat and sugar. The more of these molecules a food contains, the more quickly it will cook, which is why high-fat, high-water fish steaks are ideal. As a bonus, water doesn’t boil in the microwave until it reaches 105 C, so whatever you cook will retain more moisture. And finally, they preserve more of the healthy pigments that give salmon its orange-pink colour and fragrant aroma.

大多数微波炉都使用频率2.45G赫兹的微波。这个频率的微波很容易被水、脂肪和糖所吸收。食物分子中包含的水、脂肪和糖越多,就会在微波炉中熟得越快。高含脂量、高含水量的鱼排就非常适合微波炉烹制。另外,在微波炉中,水分要到105℃才会沸腾,因此不管你怎么烹调,都会保留住水分。最后,微波炉还能够保存使三文鱼呈现粉橙色的天然色素及其特有的芳香气味。

“Coming from my background I never would have dreamed of cooking fish in the microwave, but it really works,” says Hodges.

"在我的厨师生涯里,我从来没想到过用微波炉做菜,但它真的很有用,"霍吉斯说。

One dish Hodges was particularly keen to recreate in ready meal form was Roka’s salmon teriyaki, which is cooked over charcoal on a traditional Japanese barbecue called a robata. To make sure the fillets are steeped in Maillard compounds, just like the real deal, first they’re seared in a 300C (572F) degree oven. “The salmon is already coated with the sauce and the oven just creates a beautiful glaze, as if you were doing it on a robata in a restaurant,” he says.

霍吉斯尤其喜欢的一道速食菜肴是Roka烧烤三文鱼。这道菜原本是在日本烧烤餐厅的炭火炉上烤制而成。为了确保三文鱼片像在烧烤店里那样获得美拉德反应产物,需要先用300℃的烤炉预先烤制。"三文鱼片上已经覆盖了一层酱汁,烤炉赋予它漂亮的光泽,就像在日本烧烤店里的炭火炉上一样,"他说。

To avoid overcooking it – after all, the fish still has to be microwaved – the golden fish is removed after just a minute and cooled right down. “It’s really about stopping the cooking process quickly,” says Hodges. “We have one of the best large chillers you can buy, and this will take something from, say, 100 degrees to under zero in less than five minutes.”

为了防止烤过头,鱼肉终归还要在微波炉里做熟,金黄色的鱼肉在烤制一分钟之后就被撤出烤炉迅速冷却。"必须迅速停止加热,"霍吉斯说。"我们有市场上最好的大型冷却机,在不到5分钟时间里就能把鱼肉温度由100℃降至0度以下。"

These are extremely popular in the industry – in fact, they’re often the only way to comply with food safety regulations – because they have the added benefit of preventing harmful bacteria from growing in the comfortable, lukewarm conditions while the food is cooling down.

这种做法在行业内非常普遍,事实上,这往往是满足食品安全标准要求的唯一手段,同时,还能防止有害细菌在食品温度下降后的舒适条件下滋生。
 
Which brings us to the next problem. Most microwaveable dinners come partially-cooked, which means they must run the gauntlet of all the same perils that ruin leftovers. The biggest culprit is the dreaded “warmed-over flavour”, a rancid taste that tends to develop in meat that’s been cooked and then refrigerated. It’s often said to taste like a cross between cardboard and damp dog hair, and occurs as a result of oxygen reacting with fats in the meat.

现在我们来到了下一个问题。大多数微波炉速食食品都属于半成品,因此它们必须经受与剩饭菜一样的严酷条件而不至腐败。最大的敌人就是可怕的"再加热味道",一种先做熟,再冷藏的肉类散发出的腐败气味,很多人把它描述成硬纸板和湿狗毛的混合气味。这种气味是氧气与肉类中的脂肪发生反应后出现的。

In this case, most manufacturers overcome the problem by adding antioxidants, which prevent oxygen from reacting with fat by sacrificing themselves. These can include synthetic E numbers such as butylated hydroxytoluene (E321), but also herbs – rosemary is particularly effective – spices, vitamins, and even lemon juice. Ironically, the Maillard compounds that are often absent in ready meals are also potent antioxidants.

大多数食品企业通过添加抗氧化剂,防止氧气与脂肪发生反应来解决这个问题。常见的抗氧化剂有丁基羟基甲苯(E321),还可使用香草(尤其是迷迭香)、香辛料、维生素甚至柠檬汁。讽刺的是,速食食品中不存在的美拉德物质却都是强抗氧化剂。

Other manufacturers just make sure their food is eaten before this happens. “There’s food in the marketplace that has a shelf life of up to two months and actually I think it’s kind of scary. In one instance we found a company that was making refrigerated children’s food that was supposed to be healthy and it had a shelf life of three months,” says Hodges.

其他食品企业则选择让消费者在食品腐败前将其吃掉。"市场上食品的保质期最长是两个月,我感觉这很可怕。我们曾经发现有一家公司生产的冷藏儿童食品保质期居然有3个月,他们居然认为在这么长的时间里食品还能保持健康卫生,"霍吉斯表示。

There’s also the issue of soggy food. The cold air in microwaves means that steam tends to quickly condense back into liquid water. This stops food from developing a crispy surface and even actively adds moisture into foods that already have one – preventing crusts from forming on bread and turning pizza soggy.

另一个问题是食物潮湿现象。微波炉内的空气温度很低,水蒸汽很快就会冷凝成为液体水,这样食物不会出现酥脆的表面,并且含水量大的食品会更湿,这样,面包不会有脆皮,披萨饼也很潮湿。

But here too, science can help. Enter “susceptor packaging”, a clever new technology that can crisp bread in the microwave. It usually consists of a cardboard tray lined with plastic, which in turn is coated in a fine film of metal. Popular wisdom has it that metal gets so hot in the microwave that it will definitely burn your house down with a massive, apocalyptic explosion. But this isn’t strictly true.

在这里,科技再一次发挥出神奇的力量。一种名为"自加热包装"的创新技术能够帮你在微波炉里烤出酥脆的面包。这种技术采用的硬纸板有一层塑料衬层,上面覆盖有金属箔。一般人会认为,在微波炉中,金属会迅速升温,然后微波炉发生爆炸毁掉你的家。但这种情况不会发生。

It actually depends on its shape; flat sheets tend to just get very hot, while anything angular, such as a piece of foil shaped to cover a dish, will eventually ignite. It’s down to the way electric charges accumulate more on angular surfaces, and it means that susceptor packaging gets just hot enough for a crust to form, but not so much that you’ll be scraping embers out of the microwave for the next few months. They’re also just hot enough for the Maillard reaction to turn your dinner a more appetising shade.

这取决于形状。平坦的金属箔会迅速升温,而棱状金属箔,例如包裹住一条鱼的金属箔,在持续加热下,最终会产生极高温度。电荷会在尖角处聚集,于是"自加热包装"能够得到足够热量烤干食物的外皮,但却并不会在微波炉内引发火灾。另外,这一温度足以支持美拉德反应,从而保障了食物的色香味。

But perhaps the most offensive failure of microwaves is that bland ready meal taste. This is, of course, partly to do with the lack of browning, but it’s also down to the fact that microwaves hold cold air. Conventional ovens dry the surface of food, which prevents aromatic compounds from being able to escape as they evaporate. The hard crust of say, a lasagne cooked this way, forms an impenetrable barrier. Meanwhile the soft, gelatinous mess of bechamel and cheese fresh from the microwave is no match for fleeing flavours.

微波炉最大的缺陷可能在于速食食品的口味过于寡淡。其原因之一在于缺乏褐变过程,还在于微波炉内温度过低。传统烤炉能够烤干食物表面,食物表面烤出的一层硬皮形成了一层无法穿透的屏障,从而防止芳香物质蒸发逃逸。用微波炉烹制时,柔软胶状的酱料和奶酪在芳香物质逃逸后会变得索然无味。

Hodges overcomes this flaw by incorporating pickled vegetables into his meals. “This helps with adding a real touch of fresh flavour and acidity, giving the dish a less homogenous palate,” he says.

为了解决这个问题,霍吉斯在菜肴中加入了腌制蔬菜。"这能增加新鲜口味和酸度,让菜肴口味不再千篇一律,"他说。

Ever since being invented by accident in 1945 when an engineer inadvertently melted his snack, microwaves have been revolutionising how we eat. Supermarket lasagnes may never have that crispy, oven-scorched topping that we crave, but science is making them more delicious every day. Failing that, you could always, ahem, heat your ready meal in the oven.

1945年,一位工程师不小心把自己的点心在微波下融化,从而阴差阳错地发明了微波炉。自那时起,微波炉就一直在改变着我们的烹调方式。超市里的意式千层面可能从来没有如同烤炉烤制出的那样具有酥脆的表皮和盖料,但是科技的进步正在日益改善着它们的口味。否则,你就只能用烤炉做速食食品了。

“全文请访问纽约时报中文网,本文发表于纽约时报中文网(http://cn.nytimes.com),版权归纽约时报公司所有。任何单位及个人未经许可,不得擅自转载或翻译。订阅纽约时报中文网新闻电邮:http://nytcn.me/subscription/”

相关文章列表