Recent fervor surrounding the aging of beer has brought about a revolution of barrel aging techniques, and a frenzy of internet banter. Beer geeks from all round the globe accumulate massive cellars and stockpile rows upon rows of different vintage brews in pursuit of aging their malt beverages to perfection. “Verticals” (beers of a certain type from every year’s production) are feverishly sought after, while people spend massive amounts of money on decade or older beer bottles. But why? Many will tell you that certain beers can only get better with age, and to some extent, they are correct. But mostly I believe they are not…
The prevailing opinion among beer aficionados is that the higher the alcohol (and generally sugar as well), the better the brew will age. Barley wines, Imperial Stouts, and strong Belgian ales most readily tend to fall into this category. With their robust ethanol percentages and high gravities, they tend to succumb to the woes of oxidation to a lesser degree. Many say that a few years on a good high alcohol barley wine or stout will ‘mellow it out’ and bring out ‘more depth in flavor.’ Thought the former might be true in some cases of highly hopped American style barley wines or imperial stout, I surely could not endorse the latter with any degree of fortitude.
Modern packaging equipment allows for no more than 50 ppb of oxygen in beer. It is quite amazing that brewing technology has brought us to this point, though perfection has still not been attained. Almost all types of beer will fall victim to this minute problem and will be faced with serious problems down the road with respect to staleness as a function of oxidation. This malice comes in at least 4 main forms: Lipid oxidation, hop quality deterioration, polyphenol oxidation, and Maillard reactions. Though there are dozens of beer specific variables that determine the nature of each of these forms of degradation, each is interesting in its own way.
It is true that some examples of high alcohol brews mellow out with age. It is especially true, however, for beers with a high percentage of bittering compounds such as α-acid, β-acids, and iso-α-acids. For a beer to take on the qualities required for a hop-induced perception of bitterness, hops must be boiled so as their bountiful bittering acids can isomerize and thus become soluble in water. It’s all downhill from here as the dreaded oxidation has already set in. Oddly enough, β-acids have largely already oxidized during both hop storage and during the boil due to the instability of their chemical nature. This evil it seems, cannot be avoided. Even the most minute quantities of oxygen (on the order of PPB) has an effect on the structure of α-acids and iso-α-acids, and as such time will only dull the flavors associated with a nice fresh IPA. But how does this translate to a beer without the qualities of a hop-forward style such as an IPA or DIPA? I find that it is most noticeable in American style barley wines and Imperial stouts with high levels of α-acids and iso-α-acids. Because hop flavors tend to be the first thing to go when aging beer, those abrasively bitter barley wines will become much more sweet, allowing for the dimensions of the malt character to come out more fully. The same is true for imperial stouts, though the change isn’t as profound for me due to the already ridiculous gravities imperial stouts posses. Be careful though, for there is a sensitive curve: age too long and you will face other problems, which I’ll discuss in more detail later.
Despite many pre-supposition held by beer-geeks and the beer naïve alike, all beer does contain a small amount of lipids, or fat. The mass-marketed macro breweries are all pushing super light, low carbohydrate beer, which is reasonable due to the fact that the majority of calories in beer do come from carbs. It only takes a small amount of chemical conversion to create a mess of problems in a beer, and as such, it is useful to look on a smaller scale. Though many of the lipids related problems are largely unavoidable, they must be addressed as well. The specific problem lipid type for brewers and beer agers comes in the form of the unsaturated fatty acid. Through either enzymatic or autoxidative processes (both of which occur because of high heat levels during the wort boil), reactive oxygen species are created, which in turn damage double bonds on the fatty acid structure, finally leading to production of 2-nonenal. This final byproduct is thoroughly unpleasant and can be likened to aromas of oldness, staleness and cardboard. Luckily, the addition of yeast during fermentation mitigates this production to some extent, which is why levels of 2-nonenal are generally imperceptible. This process does, however, have implications of oxygen-introduction moderation during the brewing process as 2nonenal producing processes following the boil.
Maillard reactions tend to be much more severe to the longevity of beer as far as quality is concerned. A Maillard reaction is any reaction between a reducing sugar (glucose and maltose as far as we beer drinkers are concerned) and an amino acid. Many positive features can come out of many of these reaction types, which for our purposes include flavors and aromas of nut, bread, toast, roast, and most importantly, melanoidin production. These qualities are gained primarily during the wort boil, but can also occur at elevated temperatures during cellaring. Interestingly enough, the production of melanoidins has been shown to have an anti-oxidant property, though the chemicals production is limited to the time of the boil, thus its positive properties do not get better after bottling. Maillard reactions can also create intermediaries such as α-dicarbonyl, and Strecker aldehydes, which are associated with negative flavor profiles. So what should you do to mitigate these factors? Obviously you should drink your beer fresh whenever possible, but if you must age, age cold.
Polyphenols are generally associated with negative flavor profiles, though the chemical is inherent in all beer. Through their oxidation with extended aging, these compounds can also become oxidized, leading to reactions with certain proteins that cause the dreaded oxidation haze. Depending levels and aging time, this can greatly affect the astringency and tannic nature of an aged beer.
Can all these forms of oxidation be chalked up as necessary evils? Future research will suggest not. At its core, beer oxidation comes from reactions of OH- (which is highly reactive) and Peroxide (which has the propensity to decompose into a highly reactive free radical form) with ethanol, sugars, polyphenols, and fatty acids. This of course leads to the staling cardboard-like nature of your prized brew. So what about anti-oxidants? Could the famed health enhancer be used to make higher quality, longer lasting beer? It’s certainly possible.
Sulfite has long been recognized in the wine industry as having preservative, anti-oxidation effects. Sulfite and all forms of anti-oxidants act by quelling peroxides and metals that contribute to free radical formation. Hydrogen peroxide and hyroperoxide are stable enough for staling effects to be mitigated by antioxidants, though OH- radicals are not stable enough to be quelled, thus will react with ethanol to produce negative compounds such as acetaldehyde and hydroperoxyl radicals- yuck! Even if sulfite was completely effective at eliminating this issue, it tastes and smells horrible in high enough concentrations. Though other chemicals such as lactone have been shown to delay the onset of oxidation (read US patent 5455052), further study still must be conducted for the field as it relates to the brewing industry.
What is the general theme of this article? There are certain cases where aging beer can have positive effects on your perceptions. Be careful though, because if you wait too long everything will become one dimensional, possible stale or musty, and contain homogenized flavors which just may be nasty. I suppose I enjoy a 4-year old Thomas Hardy’s just as much as the next guy- all I’m saying is take a step back and think about it. If you must cellar, keep it dark and keep it cold.
There are certain exceptions to the rules of oxidized beer, but you won’t be looking at any high gravity or ABV statistics: Enter the lambic and the gueuze. Sour beer in general has an interesting resistance to the phenomenon of aging, but more on that with my next update...
- James Otey
The prevailing opinion among beer aficionados is that the higher the alcohol (and generally sugar as well), the better the brew will age. Barley wines, Imperial Stouts, and strong Belgian ales most readily tend to fall into this category. With their robust ethanol percentages and high gravities, they tend to succumb to the woes of oxidation to a lesser degree. Many say that a few years on a good high alcohol barley wine or stout will ‘mellow it out’ and bring out ‘more depth in flavor.’ Thought the former might be true in some cases of highly hopped American style barley wines or imperial stout, I surely could not endorse the latter with any degree of fortitude.
Modern packaging equipment allows for no more than 50 ppb of oxygen in beer. It is quite amazing that brewing technology has brought us to this point, though perfection has still not been attained. Almost all types of beer will fall victim to this minute problem and will be faced with serious problems down the road with respect to staleness as a function of oxidation. This malice comes in at least 4 main forms: Lipid oxidation, hop quality deterioration, polyphenol oxidation, and Maillard reactions. Though there are dozens of beer specific variables that determine the nature of each of these forms of degradation, each is interesting in its own way.
It is true that some examples of high alcohol brews mellow out with age. It is especially true, however, for beers with a high percentage of bittering compounds such as α-acid, β-acids, and iso-α-acids. For a beer to take on the qualities required for a hop-induced perception of bitterness, hops must be boiled so as their bountiful bittering acids can isomerize and thus become soluble in water. It’s all downhill from here as the dreaded oxidation has already set in. Oddly enough, β-acids have largely already oxidized during both hop storage and during the boil due to the instability of their chemical nature. This evil it seems, cannot be avoided. Even the most minute quantities of oxygen (on the order of PPB) has an effect on the structure of α-acids and iso-α-acids, and as such time will only dull the flavors associated with a nice fresh IPA. But how does this translate to a beer without the qualities of a hop-forward style such as an IPA or DIPA? I find that it is most noticeable in American style barley wines and Imperial stouts with high levels of α-acids and iso-α-acids. Because hop flavors tend to be the first thing to go when aging beer, those abrasively bitter barley wines will become much more sweet, allowing for the dimensions of the malt character to come out more fully. The same is true for imperial stouts, though the change isn’t as profound for me due to the already ridiculous gravities imperial stouts posses. Be careful though, for there is a sensitive curve: age too long and you will face other problems, which I’ll discuss in more detail later.
Despite many pre-supposition held by beer-geeks and the beer naïve alike, all beer does contain a small amount of lipids, or fat. The mass-marketed macro breweries are all pushing super light, low carbohydrate beer, which is reasonable due to the fact that the majority of calories in beer do come from carbs. It only takes a small amount of chemical conversion to create a mess of problems in a beer, and as such, it is useful to look on a smaller scale. Though many of the lipids related problems are largely unavoidable, they must be addressed as well. The specific problem lipid type for brewers and beer agers comes in the form of the unsaturated fatty acid. Through either enzymatic or autoxidative processes (both of which occur because of high heat levels during the wort boil), reactive oxygen species are created, which in turn damage double bonds on the fatty acid structure, finally leading to production of 2-nonenal. This final byproduct is thoroughly unpleasant and can be likened to aromas of oldness, staleness and cardboard. Luckily, the addition of yeast during fermentation mitigates this production to some extent, which is why levels of 2-nonenal are generally imperceptible. This process does, however, have implications of oxygen-introduction moderation during the brewing process as 2nonenal producing processes following the boil.
Maillard reactions tend to be much more severe to the longevity of beer as far as quality is concerned. A Maillard reaction is any reaction between a reducing sugar (glucose and maltose as far as we beer drinkers are concerned) and an amino acid. Many positive features can come out of many of these reaction types, which for our purposes include flavors and aromas of nut, bread, toast, roast, and most importantly, melanoidin production. These qualities are gained primarily during the wort boil, but can also occur at elevated temperatures during cellaring. Interestingly enough, the production of melanoidins has been shown to have an anti-oxidant property, though the chemicals production is limited to the time of the boil, thus its positive properties do not get better after bottling. Maillard reactions can also create intermediaries such as α-dicarbonyl, and Strecker aldehydes, which are associated with negative flavor profiles. So what should you do to mitigate these factors? Obviously you should drink your beer fresh whenever possible, but if you must age, age cold.
Polyphenols are generally associated with negative flavor profiles, though the chemical is inherent in all beer. Through their oxidation with extended aging, these compounds can also become oxidized, leading to reactions with certain proteins that cause the dreaded oxidation haze. Depending levels and aging time, this can greatly affect the astringency and tannic nature of an aged beer.
Can all these forms of oxidation be chalked up as necessary evils? Future research will suggest not. At its core, beer oxidation comes from reactions of OH- (which is highly reactive) and Peroxide (which has the propensity to decompose into a highly reactive free radical form) with ethanol, sugars, polyphenols, and fatty acids. This of course leads to the staling cardboard-like nature of your prized brew. So what about anti-oxidants? Could the famed health enhancer be used to make higher quality, longer lasting beer? It’s certainly possible.
Sulfite has long been recognized in the wine industry as having preservative, anti-oxidation effects. Sulfite and all forms of anti-oxidants act by quelling peroxides and metals that contribute to free radical formation. Hydrogen peroxide and hyroperoxide are stable enough for staling effects to be mitigated by antioxidants, though OH- radicals are not stable enough to be quelled, thus will react with ethanol to produce negative compounds such as acetaldehyde and hydroperoxyl radicals- yuck! Even if sulfite was completely effective at eliminating this issue, it tastes and smells horrible in high enough concentrations. Though other chemicals such as lactone have been shown to delay the onset of oxidation (read US patent 5455052), further study still must be conducted for the field as it relates to the brewing industry.
What is the general theme of this article? There are certain cases where aging beer can have positive effects on your perceptions. Be careful though, because if you wait too long everything will become one dimensional, possible stale or musty, and contain homogenized flavors which just may be nasty. I suppose I enjoy a 4-year old Thomas Hardy’s just as much as the next guy- all I’m saying is take a step back and think about it. If you must cellar, keep it dark and keep it cold.
There are certain exceptions to the rules of oxidized beer, but you won’t be looking at any high gravity or ABV statistics: Enter the lambic and the gueuze. Sour beer in general has an interesting resistance to the phenomenon of aging, but more on that with my next update...
- James Otey
References
Vanderhaegen, B, Nevin, H, Verachtert, H, & Derdenlinckx, G. (2004). The Chemistry of beer aging- a critical review. Elsevier, Retrieved from
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