The spirit beverages of vodka and gin are often produced from a neutral spirits base. These neutral spirits are derived from the distillation of fermented carbohydrates of agricultural origin. The fermentations in the production of these beverages are not often reported in great detail and to some extent are shrouded in mystery. The roles of fermentation and the yeast Saccharomyces cerevisiae are essential to the complete process, and without fermentation there would not be alcohol to distil. Nevertheless, it is not the yeast that is perceived to contribute to the distinctive consumer experiences, which are associated with these beverages. However, there are opportunities for the development of new strains of S. cerevisiae for the production of neutral spirits, which have a high ethanol yield, are tolerant of ethanol stress, and produce low levels of congeners. Full article

Whisk(e)y is a major global distilled spirit beverage. Whiskies are produced from cereal starches that are saccharified, fermented and distilled prior to spirit maturation. The strain of Saccharomyces cerevisiae employed in whisky fermentations is crucially important not only in terms of ethanol yields, but also for production of minor yeast metabolites which collectively contribute to development of spirit flavour and aroma characteristics. Distillers must therefore pay very careful attention to the strain of yeast exploited to ensure consistency of fermentation performance and spirit congener profiles. In the Scotch whisky industry, initiatives to address sustainability issues facing the industry (for example, reduced energy and water usage) have resulted in a growing awareness regarding criteria for selecting new distilling yeasts with improved efficiency. For example, there is now a desire for Scotch whisky distilling yeasts to perform under more challenging conditions such as high gravity wort fermentations. This article highlights the important roles of S. cerevisiae strains in whisky production (with particular emphasis on Scotch) and describes key fermentation performance attributes sought in distiller’s yeast, such as high alcohol yields, stress tolerance and desirable congener profiles. We hope that the information herein will be useful for whisky producers and yeast suppliers in selecting new distilling strains of S. cerevisiae, and for the scientific community to stimulate further research in this area. Full article

A perfectly balanced wine can be said to create a symphony in the mouth. To achieve the sublime, both in wine and music, requires imagination and skilled orchestration of artistic craftmanship. For wine, inventiveness starts in the vineyard. Similar to a composer of music, the grapegrower produces grapes through a multitude of specifications to achieve a quality result. Different Vitis vinifera grape varieties allow the creation of wine of different genres. Akin to a conductor of music, the winemaker decides what genre to create and considers resources required to realise the grape’s potential. A primary consideration is the yeast: whether to inoculate the grape juice or leave it ‘wild’; whether to inoculate with a specific strain of Saccharomyces or a combination of Saccharomyces strains; or whether to proceed with a non-Saccharomyces species? Whilst the various Saccharomyces and non-Saccharomyces yeasts perform their role during fermentation, the performance is not over until the ‘fat lady’ (S. cerevisiae) has sung (i.e., the grape sugar has been fermented to specified dryness and alcoholic fermentation is complete). Is the wine harmonious or discordant? Will the consumer demand an encore and make a repeat purchase? Understanding consumer needs lets winemakers orchestrate different symphonies (i.e., wine styles) using single- or multi-species ferments. Some consumers will choose the sounds of a philharmonic orchestra comprising a great range of diverse instrumentalists (as is the case with wine created from spontaneous fermentation); some will prefer to listen to a smaller ensemble (analogous to wine produced by a selected group of non-Saccharomyces and Saccharomyces yeast); and others will favour the well-known and reliable superstar soprano (i.e., S. cerevisiae). But what if a digital music synthesizer—such as a synthetic yeast—becomes available that can produce any music genre with the purest of sounds by the touch of a few buttons? Will synthesisers spoil the character of the music and lead to the loss of the much-lauded romantic mystique? Or will music synthesisers support composers and conductors to create novel compositions and even higher quality performances that will thrill audiences? This article explores these and other relevant questions in the context of winemaking and the role that yeast and its genomics play in the betterment of wine quality. Full article

The characteristic flavour and aroma of any beer is, in large part, determined by the yeast strain employed and the wort composition. In addition, properties such as flocculation, wort fermentation ability (including the uptake of wort sugars, amino acids, and peptides), ethanol and osmotic pressure tolerance together with oxygen requirements have a critical impact on fermentation performance. Yeast management between fermentations is also a critical brewing parameter. Brewer’s yeasts are mostly part of the genus Saccharomyces. Ale yeasts belong to the species Saccharomyces cerevisiae and lager yeasts to the species Saccharomyces pastorianus. The latter is an interspecies hybrid between S. cerevisiae and Saccharomyces eubayanus. Brewer’s yeast strains are facultative anaerobes—they are able to grow in the presence or absence of oxygen and this ability supports their property as an important industrial microorganism. This article covers important aspects of Saccharomyces molecular biology, physiology, and metabolism that is involved in wort fermentation and beer production. Full article

Alcoholic beverages are produced following the fermentation of sugars by yeasts, mainly (but not exclusively) strains of the species, Saccharomyces cerevisiae. The sugary starting materials may emanate from cereal starches (which require enzymatic pre-hydrolysis) in the case of beers and whiskies, sucrose-rich plants (molasses or sugar juice from sugarcane) in the case of rums, or from fruits (which do not require pre-hydrolysis) in the case of wines and brandies. In the presence of sugars, together with other essential nutrients such as amino acids, minerals and vitamins, S. cerevisiae will conduct fermentative metabolism to ethanol and carbon dioxide (as the primary fermentation metabolites) as the cells strive to make energy and regenerate the coenzyme NAD⁺ under anaerobic conditions. Yeasts will also produce numerous secondary metabolites which act as important beverage flavour congeners, including higher alcohols, esters, carbonyls and sulphur compounds. These are very important in dictating the final flavour and aroma characteristics of beverages such as beer and wine, but also in distilled beverages such as whisky, rum and brandy. Therefore, yeasts are of vital importance in providing the alcohol content and the sensory profiles of such beverages. This Introductory Chapter reviews, in general, the growth, physiology and metabolism of S. cerevisiae in alcoholic beverage fermentations. Full article