Yeast management

It is important to emphasize that although considerable information is available about brewer s yeast fermentation per se (e.g. Boulton Quain, 2(X)1 Sofie et al., 2010 Stewart Russell, 2009), by comparison, basic detailed information on yeast management processes between wort fermentations has been lacking. Indeed, although the overall fermentation procedures and control have become very sophisticated, yeast management was, until recently, the poor relation of the process. 

Yeast management can be divided into a number of overlapping procedures  

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During most of the fermentation ethanol production procedures, a yeast culture is used only once for a single fermentation cycle. However, in brewing, the yeast culture is harvested at the end of a fermentation for reuse in a subsequent fermentation. Between fermentations, the cropped yeast is normally stored before being repitched. As a consequence of this procedure, the yeast culture must be carefully managed between fermentations to maintain its quality. The steps in this yeast management procedure have been discussed in this chapter. 

Five chapters are devoted to brewer s yeast and they consider, in appropriate detail, their taxonomy and related areas such as identification and characterization. Wort fermentation and metabolism are discussed and, in particular, the metabolic engineering of these organisms. The fact that brewer s yeast cultures are normally recycled through a number of wort fermentations is emphasized and details of yeast management between fermentations are discussed. 

Brennerei, /. distillery distillation, distilling plant (for burning lime, etc.) kiln burning (of lime, brick, etc.), -betrieb, m. distillery management or operation, -hefe,/. distillery yeast, -maische, /. distillery mash. 

Ertugrul S, San NO, Donmez G (2009) Treatment of dye (Remazol Blue) and heavy metals using yeast cells with the purpose of managing polluted textile wastewaters. Ecol Eng 35 128-134... 

In order to better manage winemaking and avoid defects, the use of selected starter yeast strains, suited to specific conditions, are a standard feature of modem in winemaking. These strains belong to the same yeast species usually found in spontaneous Amarone fermentations S. cerevisiae and S. bayanus. 

Effect of Yeast on Fermentation. North Coast enologists recognize the important effects yeast strains have on the management of the fermentation, its evenness and completion, and the wine composition. Rankine (23) reviewed the different effects of yeast strain on wine composition and noted especially the relationship of yeast strain to sulfur dioxide, hydrogen sulfide, and acetaldehyde production. 

Fermentations in this temperature range will take two to eight weeks to complete, depending on yeast strain, juice composition, and temperature management. 

In a number of different bioreactor cultivations with bacteria, yeasts, molds and mammalian cells, it was shown how the electronic nose can serve to visualize the course of the processes. The pattern recognition method that best manages to mirror the complex sensor array responses during extended cultivations is two- or three-dimensional PCA. Examples from such electronic nose applications are given below. 

Swiegers, J.H., Francis, I.L., Herderich, M. Pretorius, I.S. (2006). Meeting consumer expectations through management in vineyard and winery, the choice of yeast for fermentation offers great potential to adjust the aroma of Sauvignon Blanc. Wine Ind. J., 21, 34 2. 

Reynolds, A. G., Schlosser, J., Power, R., Roberts, R., WiUwerth, J., de Savigny, C. (2007) Magnitude and interaction of viticultural and enological effects. I. Impact of canopy management and yeast strain on sensory and chemical composition of Chardonnay Musque. American Journal of Etiology and Viticulture, 58, 12-24. 

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