From New Jersey: A demanding, five-part, question comes to me from New Jersey. It is on a topic that is often raised with me. Do beers mature with age? The questioner goes on to ask:
1. What are some benefits of cellaring beers?

MJ: It is important to stress that 99.9 per cent of beers worldwide are made to be consumed immediately they leave the brewery. In my view, the only exceptions are:

(a). Cask-conditioned beers. These are filled into the cask before secondary fermentation is complete. They contain live yeast in suspension, and some unfermented malt sugars. In some instances, a small dosage of sugar is added to feed the yeast. Cask-conditioned beers are usually cellared in the pub, not the home. They clarify; gain a natural, characteristically gentle, carbonation; and develop more complexity of flavor, over a period of days – and occasionally weeks, so long as the cask is not broached. Once the cask has been tapped, the beer should be consumed within hours rather than days.

(b). Bottle-conditioned beers. (The term "re-fermentation in the bottle", used by the Belgians, is perhaps clearer). This term indicates that the beer is unfiltered. Or only partially filtered. Or only partially centifruged. Again, the idea is that some living yeast remains. Alternatively, the beer may have been fully filtered or centrifuged, then given a very small dose of fresh yeast. The original fermentation may have been arrested at a point where there is some residual sugar left to feed this yeast. Alternatively, a small amount of sugar or wort ("unfermented beer") may have been added for this purpose.

How long will such a beer mature? No hard-and-fast rules here. Even a light-bodied beer like a bottle-conditioned Berliner Weisse or Worthington White Shield can develop complexity during three to six months’ cellaring in a cool, dark, place. Bigger-bodied beers, with plenty of residual sugars and living yeast can be matured for years. This would apply to strong brown ales like Liefmans, the stronger Trappist products, and (if they are bottle-conditioned) Barley Wines and Imperial Stouts.

Not all year-dated beers are intended for laying down, but a "vintage" on the label does suggest that the beer might benefit from storage. The date also helps you keep track of the passing years. .

(c). Some brewers feel that even filtered and/or pasteurised beers can benefit from cellaring if they are sufficiently full in flavors, and high in alcohol. This has been suggested in respect of John Willie Lees Harvest Ale, from England, and Carnegie Porter, from Sweden. The argument is that the flavors meld. Perhaps they do, over a short period, but I doubt the advantage of keeping such a beer for much more than a year. Alcohol protects beer against deterioration, but not completely. I have carried out comparative tastings of several such beers, but especially Lees Harvest Ale.

2. What are the pitfalls associated with cellaring beers?

MJ: Hop character can diminish even within a few weeks. This is not always an issue, as most beers intended for cellaring lean less toward hoppiness than maltiness. If "re-fermentation" does not proceed properly, the beer may be excessively malty and syrupy or soupy. Dead yeast can give "meaty" flavors. The British sometimes describe this as being like Marmite, the Australians as resembling Vegemite (both are products derived from brewers’ waste yeast and used as snack foods, spread on toast). The re-fermentation in he bottle should create carbon dioxide, which will protect the beer against oxygen. However there will almost always eventually be some oxidation. This creates toffeeish, Madeira-like flavors. These would be unpleasant in a dryish bottle-condtioned beer like Duvel, but can complement the flavors in bigger-bodied, malty, beers. This "Maderisation" can also be found in Champagne and even whisky. If a beer is not properly sealed, it may simply taste sour.

3. Have you ever stored beers? If so, were you satisfied with the results?

MJ: Travelling as much as I do, it is difficult to be methodical, but I do have a miscellany of maturing beers in my cellar. The results have been variable.

4. Name a specific beer you have cellared, how long it aged and how the flavor changed in time.

MJ: The examples that linger in my memory have been cellared at the brewery. An 18-year-old Thomas Hardy’s Ale was Maderised but elegant. A 21-year-old Chimay had become substantially leaner, drier and winier, with port-like flavors. It was astonishingly complex.

5. What advice would you have for the novice who is contemplating laying down some beers?

MJ: Never refrigerate the beer, as this will prevent the yeast from working. Keep it somewhere dark, not too damp or musty, with a cool and reasonably consistent temperature. If it has a real cork, lay it on its side, in a wine-rack. When you are ready to serve it, carry it gently, so that the yeast sediment is not shaken.