Among craft brewers one occasionally hears the question: “Who aged beer in wooden barrels first?” Since barrels have been employed for storing liquid foods for millennia and beer brewing itself is many centuries older than the proper art of cooperage, asking such a question would seem puerile. The question appears impossible to answer – that is, until one begins inserting caveats. Though beer has been stored in barrels for a long time, by and large, brewers over many centuries have attempted to avoid allowing the wood to impart its own flavor to the beer – and they especially wanted to prevent any of the flavors and aromas derived from the beverage or food previously stored in the barrel to corrupt its contents. As with so much else, however, there has been a sea change in the use of barrels amongst craft brewers. We will conclude our discussion in the final installment of this series by taking a closer look at how brewers have awoken to the potential barrels can offer in the creation of unique and characterful beers.
Until around 20 years ago, secondary fermentation in the bottle was widespread among most breweries producing Southern German-style wheat beer. However, since then, the majority of them have abandoned traditional bottle conditioning in favor of secondary fermentation in tanks. There are multiple reasons behind the move away from bottle conditioning aside from the need to simplify and standardize the production process. It was primarily the desire to avoid yeast autolysis and to achieve uniform and stable levels of turbidity which were the motivation for seeking alternatives to bottle conditioning.
Key performance metrics for efficiency are established tools for quantifying bottling line performance. They provide a comparison of ideal volume and actual production volume. Expressed as a ratio, this figure can be used to quantify production losses. However, as is frequently the case, the devil is in the details; therefore, selecting the correct metric is essential.
Entering the fantastical realm of microbes by becoming engrossed in their goings-on under the lens of a microscope can be compared to Alice stepping through the looking glass. Tumbling down the zymurgical rabbit hole into the distance past, we see amphorae become the first and most common containers for liquid foods. They were in use for centuries, and owing to their porosity, they were able to harbor microbial communities. These microbes ultimately affected the character of many of the liquids stored in them, including beer, the ambrosia of the Levant, Mesopotamia and Egypt during the Bronze Age. Barrels have since taken over the role of housing the microbes – both foul and fair – that inoculate their contents.
A brewery rich in tradition, Brauhaus Riegele in Augsburg, Germany, brews a total of 29 different beers. Almost all of the beers have been honored with numerous prestigious awards. In order to ensure that the beer leaves the brewery in perfect condition and remains so until it reaches the customer, the oxygen values must be reduced to a minimum and continuously analyzed, in this case with oxygen measuring devices supplied by Dr. Thiedig GmbH & Co KG, Berlin, Germany.
There is a renewed interest in barrels and the numerous ways in which they can be used to impart a unique character to beer. In the fourth installment in this series, we begin our look at the practical aspects of how the microbial communities living in wooden vessels can influence the flavor of beer. These microbes are considered spoilage organisms by most commercial brewers – but not by craft brewers.
Breweries devote continuous attention towards improving and stabilising beer quality. In order to fill the perfect beer, choice of raw materials as well as the brewing process is subject to the most stringent specifications and tests. Unfortunately, thorough quality monitoring often stops at this point.
Barrels have held beer since they were invented in the early Iron Age between 800 and 900 BCE, or perhaps even earlier, by a wood-bending folk with access to vast forests, most likely by the Celts. There has recently been a resurgence in the use of barrels among craft brewers. How these innovative brewers employ barrels to create distinctive beers is in many ways novel and unique and at the same time steeped in centuries of tradition. Beers acquire more character and complexity by spending time in barrels for a variety of reasons. In this second installment in the series, we delve into why brewers have come back to these ancient wooden vessels by looking more closely at how barrels are produced as well as the flavors and aromas the wood contributes to the beverages stored in them.
The relevance of dimethyl sulfoxide (DMSO) as a precursor of dimethyl sulfide (DMS) is discussed in the following contribution. It explains the theoretical background to formation of DMSO as well as its reduction to free DMS during beer fermentation. As a starting point for further scientific brewing investigations, this part also includes an overview of DMSO concentrations in various malt types.
The diacetyl level is regarded as an essential criterion for beer maturation. Its control is crucial for a short and consistent maturation time and thereby a dependable throughput. To prevent too high diacetyl levels generated by brewers’ yeast during fermentation the enzyme alpha-acetolactate decarboxylase (ALDC) can be applied. DuPont Industrial Biosciences, Brabrand, Denmark, developed an enzymatic solution to minimize the formation of diacetyl. Alphalase® Advance 4000 is commercially available since 2015 and especially designed to provide a short consistent maturation period; due to its concentrated form it can be applied at dosage levels as low as 0.5 to 1.0 g/hl into cold wort at the beginning of the main fermentation. The resulting effect is diacetyl levels close to or below flavor threshold at the end of the main fermentation to ensure a consistent throughput, even during peak season.
The trend, as it is known today, of ageing beer in wooden casks is spreading rapidly in artisanal (and other) fermentation cellars. However, there is nothing new about this almost global phenomenon, which dates all the way back to antiquity. This article is the first part in a new mini-series on barrel aging which will be published in the following issues of BRAUWELT International.