长沙昌恒康复医院官网:鹅肝的生产：是否该适可而止

Dec 3rd 2011 | from the print edition

2011年12月3日 | 引自印刷版

FOIE GRAS is one of the most controversial dishes on earth. To protagonists, it is simply the finest foodstuff that exists. To those opposed, it is a product of cruelty that is not far short of criminal. The overfeeding of ducks and geese, so that their livers bloat to between six and ten times their normal size and take on a buttery consistency valued by gourmets, exploits the ability of these birds to store large amounts of calorie-rich fat, which was needed to propel them on the long migrations that their wild ancestors would routinely have undertaken. The moral argument over the way foie gras is produced (by feeding the birds with grain, through a tube or a funnel) turns on whether this is merely the permissible exaggeration of a natural inclination, or is tantamount to abuse. Intriguingly, a newly published piece of research on foie-gras production suggests the quality of the product depends on exactly the same distinction.

鹅肝，地球上最具争议的食物之一。支持者把它当作世上最美味的食物，而对反对者而言，生产过程的残忍简直就是犯罪。鹅肝的生产借助于鸟类储存大量脂肪以备远距离迁徙的能力，靠过度喂食使鸭或鹅的肝脏膨胀到正常大小的6至8倍。其中所含油脂为美食家们津津乐道。鹅肝生产的道德问题主要在于其生产过程到底是合理开发，还是滥用自然资源。有趣的是，一篇新发表的研究鹅肝生产的论文提出，鹅肝是否美味，恰恰取决于此。

From the chef’s point of view, one of the disturbing things about foie gras is how variable it is. Some livers, when cooked, retain their fat and thus their rich flavour. Others lose fat when heated and end up tasting terrible. To try to work out why, Caroline Molette, a biologist at the University of Toulouse, did some experiments. Her results, just published in the Journal of Agricultural and Food Chemistry, suggest that the difference is whether the liver in question is truly healthy or not.

鹅肝味道的差异是件让厨师们头痛的事。 有些鹅肝烹煮后很好的保留了油脂，香味浓腴诱人。有些鹅肝加热后却脂肪流失非常难吃。为了找出其中的原因，图卢兹大学的生物学家卡洛琳·莫里特进行了一些研究。她发表在农业与食品化学杂志上的研究结果表明，鹅肝品质的差别在于活体肝脏是否健康。

Dr Molette and her colleagues raised 150 male mule ducks (a cross between Pekin and Muscovy ducks that is often used to produce foie gras) for 13 weeks in standard poultry-house conditions and then transferred them into individual enclosures. For a further 12 days the birds were fattened up with a mash of grain and flour—the usual procedure for enlarging their livers. They were then slaughtered, their livers removed, and those livers immediately trimmed of their blood vessels and chilled for six hours.

莫里特博士和她的同事们先在典型禽类饲养场的环境下把１５０只杂交鸭（一种北京鸭和番鸭的杂交，常被用来生产鹅肝）饲养了13周，然后把它们转入单独的圈内，用谷物和面粉的混合物（常用来养大肝脏的饲料）再喂养12天。这些杂交鸭被宰杀后，肝脏立即被取出，剔除血管后冷冻6个小时。 

So far, so normal. But instead of cooking the whole things, Dr Molette removed a 200-gram sample from each liver (an average liver weighed 550 grams) and put the rest in cold storage. She then placed each sample into a jar with a bit of salt and pepper, and cooked it for an hour. As she expected, some livers released a lot of fat when cooked while others released little. Armed with this information, she was able to turn her attention back to the uncooked sections of the livers and see if she could find any systematic chemical differences between them.

至此为止，一切正常。 之后莫里特博士从每只肝脏（平均重量550克）中切出200克样品，剩下的放回冷藏。她把这些样品加入盐和胡椒，烹煮了一个小时。和预期的一样，烹煮过程中有些样品油脂流失严重，有些油脂流失却很少。记录下这些信息后，莫里特博士再把注意力转向冷藏起来的样品，试图找出其中系统性的区别。

Using a combination of electrophoresis (which sorts proteins according to their size and electrical properties) and mass spectrometry (which sorts fragments of those proteins according to their weight), she was able to do just that. The upshot was that the fat-retaining livers were rich in a variety of proteins known to help the body digest and store food. In the fat-shedding livers, by contrast, she found high concentrations of a protein called fatty-acid-binding-protein 4. In a human liver, this would be a marker of disease. Put simply, the fat-retaining livers are healthy while the fat-shedding ones are not.

结合电泳（依照大小和反应电场给蛋白质排序）和质谱分析（依照重量给蛋白质排序），她找到了答案。结论是保留油脂的肝脏都富含一种能帮助身体消化和储存食物的蛋白质。而那些油脂流失的肝脏里含有大量一种叫做脂肪酸结合蛋白4的蛋白质。在人类的肝脏中，脂肪酸结合蛋白4是一种病变的征兆。简单来说，就是烹煮后保留油脂的肝脏是健康的肝脏，而油脂流失的那些肝脏正相反。 

Both sides of the debate, then, are right. Foie-gras production can be a form of abuse but is not necessarily so, for an enlarged liver can still be healthy. The question is, how do you draw the line?

这样说来争论的双方都是正确的。鹅肝生产可以是滥用自然资源也可能不是，因为过度喂食得来的超大肝脏也可能是健康的。问题时，界限该怎么划？

Dr Molette’s ducks were all treated similarly, and their livers were of more or less the same size (certainly, the fat-shedding ones were not systematically heavier). The search is therefore on for some way to tell in advance which animals will respond positively to extra helpings and which will not. That knowledge would help farmers, gourmets and animal-lovers alike.

莫里特博士的鸭子们都是在相同环境下饲养的，它们的肝脏大小也差不多（那些会流失油脂的肝脏并没有更重些）。那么问题的症结就在于，如何提前辨别它们之中哪些会对过度喂食有良性反应，哪些不会。  如能了解这一点，不论是对农民、美食家，还是动物爱好者都益处多多。