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62 BREWING BEVERAGE INDUSTRIES BUSINESS Ingredients Brewing is a process with few constants and a seemingly endless string of variables that conspire to form what we lovingly know as beer. From raw materials in the brewhouse to changes in brewing practice and conditions we fight to keep production standards tight towards creating consistent products from batch to batch. Nowhere is this battle more challenging than in areas of yeast management and fermentation. The Nature of the Beast that is Yeast It is said that brewers are wort-makers and yeast wranglers. We dont actually make beer but rather we create a nutrient-rich media that provides a rich banquet for the miraculous eukaryotes we employ to engorge themselves and expel alcohol CO2 and a flavour matrix that add up to form the ales and lagers we present to our customers. Trouble is should conditions not be just right yeast makes its displeasure felt in a variety of ways. Slowstalled fermentations and production of off-flavours are indicative that something is wrong either in fermentation conditions or with the yeast itself. Traditionally commercial breweries have worked to minimise the variety of yeast strains used in their brewery and this does offer some benefit. By working with a single strain in a variety of different recipes and conditions brewers can get to know the likes and dislikes of that strain under moderately differing conditions. However breweries are now required to participate in a highly competitive market by offering new recipes that challenge their skills in fermentation and yeast management. Building a portfolio of interesting beer styles requires that breweries now manage multiple strains but brewers also need to know the specific conditions under which each strain will perform towards creating products that both meet the stylistic touch points and offer an exceptional drinking experience. The Challenge of Multiple Strain Management Unlike any other industry we as brewers reuse our yeast from batch to batch. This is a great advantage from a materials-cost standpoint but it does have its downsides. The first is timing in that ideally brewers should be able to practice cone-to-cone pitching. This means transferring just the right amount of live active yeast from one fermenter just after it has completed fermentation into another fermenter filled with freshly-prepared wort. In many breweries that is a greater challenge than it sounds as wort production planning must be built around a schedule where yeast is at its peak of health in pitchable amounts from a fermenter. This is less of an issue for breweries using a single strain of yeast in beers that are of similar moderate strengths and characteristics. Yeast completing fermentation of beers at around 5 and lower is generally not too stressed by such a moderate ethanol environment so it should perform well in another batch. That said at some point of repitching many strains will begin to have shifts in their fermentation performance and characteristics. Especially beers that venture into the higher alcohol ranges can leave yeast taxed by exposure to such high alcohol ranges and their performance in the next batch of wort may exhibit signs of poor health affecting fermentation speed attenuation performance and flavor development. With this in mind breweries should conduct checks for viability of cells alivedead and if possible vitality overall fermentative performance every time yeast is reused to assess whether the yeast slurry is up to the task of fermenting another batch. Continued opposite The nature of the beast 62_Layout 1 21042016 1519 Page 1