Ask Mr. Wizard

Beers dispensed with nitrogen


Kevin Keehn • Laguna Hills, California asks,

I’d like your thoughts on beers dispensed with nitrogen. I get in frequent arguments with members of CAMRA (Campaign for Real Ale). The latest controversy is in regard to nitrogen. I quote, “Adding gas to a beer is unnatural and unnecessary. It does nothing for the taste and even less for the aroma if that matters to you. Carbon dioxide is bad enough, nitrogen is much worse.” I’ve had some beers dispensed with nitrogen in the Pacific Northwest that I thought were fantastic. Dry hopped, probably not pasteurized. Is there a scientific explanation to why nitrogen removes aroma, flavor? Or, are these people just ill informed?



Wizard relies: Although I have been known to do my fair share of trash talking, I tend to avoid jabbing with groups that are vigorous in their support of brewing tradition. There is no doubt that an individual member of a group can tarnish an organization’s image by acting like a knucklehead, but I don’t think CAMRA is some radical group without a clear understanding of the facts about beer. I suggest a review of their Web site to balance your opinions OK, so now that I have done my part to contribute to harmony in the beer community, let’s get on with the question.

I must preface my answer with a confession. I really like nitro beers when they are done correctly and have a real appreciation for the ingenuity that went into developing this method of dispense. The Guinness brewery developed this technology in the 1950’s to deal with oxidation and microbiological problems encountered with real ales, or beers naturally conditioned in the keg and dispensed using hand pumps. In order to create a similar beer using a closed system Guinness did extensive research on beer foam and wanted to know why cask ales had such a distinctive appearance and mouthfeel. Guinness researchers found that nitrogen is a key part of the head in cask ales and the nitrogen is introduced to the beer when air is mixed with beer upon dispense. The end of the story is that nitro ale, as we know it today, was born.

CAMRA does not promote beers dispensed with these non-traditional methods. They have a right to take this stand just like some wine purists think that wine should be unfiltered and fined with natural fining agents such as egg whites. Opinions about methods of production aside, there is truth in the statement that nitrogen alters beer flavor. I personally do not believe it strips flavor, rather it hides flavor. When a nitro beer is dispensed using a stout faucet, a very dense and creamy foam rises to the top. Unlike carbon dioxide foams, these foams are very stable and the nitrogen gas comprising the foam bubbles is not motivated by a large concentration gradient between the environment in the bubble and the environment outside of the bubble to leave. So how does this affect aroma?

Carbon dioxide is a very minor part of the atmosphere and when you serve a carbonated beverage there is movement of carbon dioxide out of the glass and into the environment. Aroma compounds move with the carbon dioxide and the carbonation level helps to enhance aroma. Of course aroma compounds move out of a glass without the help of carbon dioxide migration and other methods can be used to open up the aroma, for example swirling the glass and increasing the temperature. CAMRA also dislikes cold beer, and most folks sipping a pint of ale in a pub are not going to be swirling their pints like a wine enthusiast holding a Riedel Sommelier glass (those babies permit some serious swirling!). Try swirling your pint and not only are you likely to wear a portion of the contents but you erase the nice demarcations tracking your sips and risk attracting the attention of knuckleheads with thicker heads and much larger knuckles than any CAMRA member!

The other truth about carbon dioxide is that it stimulates the trigeminal nerve and contributes to the pain factor of beer. Spicy foods and phenols also stimulate this nerve. So if you are looking to quench the fire in your mouth caused by habanero salsa, a cold mug of highly carbonated beer will actually exacerbate the problem. Anyhow, it seems to me that carbonation enhances the perception of bitterness and nitro beers, by comparison, seem to dampen out bitterness.

Here is what I do. First, I ignore the argument about what is natural and necessary in brewing. Beer does not occur in nature and maltsters and brewers carefully manipulate natural ingredients to create beer. The last time I took a breath of air, a couple of milliseconds ago, I inhaled a volume of gas containing about 79% nitrogen. And the last time I walked through a brewery I could not help but smell the carbon dioxide wafting from fermentation tanks. And it is a fact that most large breweries in the world capture and reuse carbon dioxide from their fermenters to later put back in the beer or to use during packaging to pressurize bottles because, guess what, carbon dioxide is not cheap and is naturally produced during fermentation. So the “natural and necessary argument” can easily be turned into a Nerf ball and easily swatted down.

But the fundamental argument has merit and should not be discounted as merely rants by fanatics. When I brew nitro beers I formulate knowing that they will later be nitrogenated. I increase hopping, both first and late additions, to compensate for the effects that nitrogen has on aroma and bitterness. I also keep the body in check because nitrogen adds body to beer. If you begin with a full-bodied beer and then nitrogenate it you can end up with too much. The nitrogen and method of dispense should be considered an ingredient and the beer formulation must take this into account. There is indeed a great variety of really nice nitrogenated beers on the market and you can brew these beers at home to add variety to your lineup of homebrews!

Response by Ashton Lewis.