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Beer Fermentation Hops² Along

The Allagash Brewing⁴ Company, in Maine, makes a lot of "bottle-conditioned" beers—brews that get their carbonation by fermenting⁵ a second time, in the bottle, as yeast⁶ belch⁷ out CO2. "And because they do bottle conditioning they're meticulous⁸ about monitoring package pressures. It's a way for them to follow the progression of this re-fermentation in the bottle." Thomas Shellhammer is a brewing scientist at Oregon State University. Who freely acknowledges: "It's a fun job. Science and beer."

缅因州的阿拉加什酿酒公司生产许多“瓶装”啤酒，它们通过在瓶中二次发酵获得碳酸，因为酵母会喷出二氧化碳。因为他们做的是瓶子调节，所以他们对包装压力的监测非常细致。对他们来说，这是一种跟踪瓶中再发酵过程的方法。Thomas Shellhammer是俄勒冈州立大学的酿酒科学家。他坦率地承认:“这是一份有趣的工作。科学和啤酒。”

At any rate, not long ago, Allagash noticed some very high pressures in some of their bottles. Not quite exploding. But alarming enough for them to give Shellhammer a call.

不管怎么说，不久以前，阿拉加什注意到他们的一些瓶子里有些压力很大。不爆炸。但这足以让他们提高警觉给Shellhammer打电话了。

What he and his colleague Kaylyn Kirkpatrick found was that hops—the bittering agent in beers—might be to blame. Because the aromatic⁹ flowers contain enzymes¹⁰ that can chew up starch¹¹. Typically, when hop¹ flowers are added during the initial cooking of the fermentable¹² brew³, those key enzymes are denatured. And thus the flowers' only role is as a flavoring agent.

他和他的同事Kaylyn Kirkpatrick发现啤酒花——啤酒中的苦味剂——可能是罪魁祸首。因为芳香的花朵含有可以消化淀粉的酶。通常，当啤酒花在可发酵啤酒的最初烹饪过程中添加时，那些关键酶就会变性。因此，花的唯一作用就是调味剂。

But as the demand for hoppy¹³ beers has grown, brewers have been looking for other tricks to get those juicy, fruity, herbal aromas¹⁵ into beers. So they've been what’s called "dry-hopping¹⁶" beers—dumping loads of hops into the beer during or after fermentation, rather than during the initial boil.

但随着啤酒花啤酒需求的增长，酿酒商们一直在寻找其他的方法来将这些多汁、果香、香草味融入啤酒中。这就是所谓的“干跳”啤酒——在发酵过程中或发酵后，而不是在最初的煮沸过程中，往啤酒里倾倒大量的啤酒花。

"There's an upward limit to how much hops you'd want to put in the kettle because the beers just get unpalatably bitter. But if a brewer¹⁴ focuses on dry hopping they can put very large amounts of hops into beer to create intense hoppy flavors."

“你想往水壶里放多少啤酒花是有上限的，因为啤酒会变得难以下咽。”但如果啤酒酿造者专注于干跳，他们可以在啤酒中加入大量啤酒花，以产生强烈的啤酒花味道。

Problem is, adding hops late doesn't deactivate¹⁷ their starch-attacking enzymes. And they're able to break down starches¹⁸ the yeasts¹⁹ weren't able to attack, unleashing²⁰ even more sugar into the brew. And if yeast are still hanging out, as in Allagash's bottle-conditioned beers, that kickstarts additional fermentation. And that boosts alcohol by volume and carbon dioxide concentration—to potentially explosive levels.

问题是，晚加入啤酒花并不会破坏它们的淀粉攻击酶。它们能够分解淀粉酵母不能攻击，释放出更多的糖到酿造液中。如果酵母仍然存在，就像阿拉加什的瓶装啤酒一样，就会启动额外的发酵过程。这就使酒精的体积和二氧化碳浓度上升到潜在的爆炸性水平。

"Basically the hops are taking something that's considered by brewers to be unfermentable, and breaking them down to the point where they can actually re-ferment, or become fermentable, or potentially contribute to sweetness, as beer ages."

“啤酒花基本上就是把啤酒酿造者认为是不可发酵的东西，分解成可以重新发酵的部分，或者可以发酵的部分，或者可以增加甜度的部分，随着啤酒的老化。”

The full detective story is in the Journal of Agricultural and Food Chemistry. [Kaylyn R. Kirkpatrick and Thomas H. Shellhammer, Evidence of Dextrin Hydrolyzing Enzymes in Cascade²¹ Hops (Humulus lupulus)]

完整的侦探故事刊登在《农业与食品化学杂志》上。

And, in case you're wondering, Shellhammer's palate does align²² with his academic interests: "I'm kind of intrigued²³ by the hazy²⁴, juicy IPA thing that's going on right now. I'm also a fan of sort of traditional old school IPAs." He’s the rare professor whose students use IPAs to raise their GPAs.

如果你想知道，Shellhammer的口味和他的学术兴趣是一致的:“我对现在正在进行的朦胧而有趣的IPA很感兴趣。我也是传统老式IPAs的粉丝。他是少有的教授，他的学生使用IPAs来提高他们的gpa。