The useful physiological properties of<unk>  have led to their use in the field of biotechnology. Fermentation of sugars by<unk>  is the oldest and largest application of this technology. Many types of<unk> s are used for making many foods: baker's<unk>  in bread production, brewer's<unk>  in beer fermentation, and<unk>  in wine fermentation and for xylitol production. So-called red rice<unk>  is actually a mold, Monascus purpureus.<unk> s include some of the most widely used model organisms for genetics and cell biology. Alcoholic beverages Alcoholic beverages are defined as beverages that contain ethanol (C2H5OH). This ethanol is almost always produced by fermentation – the metabolism of carbohydrates by certain species of<unk> s under anaerobic or low-oxygen conditions. Beverages such as mead, wine, beer, or distilled spirits all use<unk>  at some stage of their production. A distilled beverage is a beverage containing ethanol that has been purified by distillation. Carbohydrate-containing plant material is fermented by<unk> , producing a dilute solution of ethanol in the process. Spirits such as whiskey and rum are prepared by distilling these dilute solutions of ethanol. Components other than ethanol are collected in the condensate, including water, esters, and other alcohols, which (in addition to that provided by the oak in which it may be aged) account for the flavour of the beverage. Beer<unk>  ring used by Swedish farmhouse brewers in the 19th century to preserve<unk>  between brewing sessions. Bubbles of carbon dioxide forming during beer-brewing Brewing<unk> s may be classed as "top-cropping" (or "top-fermenting") and "bottom-cropping" (or "bottom-fermenting"). Top-cropping<unk> s are so called because they form a foam at the top of the wort during fermentation. An example of a top-cropping<unk>  is Saccharomyces cerevisiae, sometimes called an "ale<unk> ". Bottom-cropping<unk> s are typically used to produce lager-type beers, though they can also produce ale-type beers. These<unk> s ferment well at low temperatures. An example of bottom-cropping<unk>  is Saccharomyces pastorianus, formerly known as S. carlsbergensis. Decades ago, taxonomists reclassified S. carlsbergensis (uvarum) as a member of S. cerevisiae, noting that the only distinct difference between the two is metabolic. Lager strains of S. cerevisiae secrete an enzyme called melibiase, allowing them to hydrolyse melibiose, a disaccharide, into more fermentable monosaccharides. Top- and bottom-cropping and cold- and warm-fermenting distinctions are largely generalizations used by laypersons to communicate to the general public. The most common top-cropping brewer's<unk> , S. cerevisiae, is the same species as the common baking<unk> . Brewer's<unk>  is also very rich in essential minerals and the B vitamins (except B12), a feature exploited in food products made from leftover (by-product)<unk>  from brewing. However, baking and brewing<unk> s typically belong to different strains, cultivated to favour different characteristics: baking<unk>  strains are more aggressive, to carbonate dough in the shortest amount of time possible; brewing<unk>  strains act more slowly but tend to produce fewer off-flavours and tolerate higher alcohol concentrations (with some strains, up to 22%). Dekkera/Brettanomyces is a genus of<unk>  known for its important role in the production of 'lambic' and specialty sour ales, along with the secondary conditioning of a particular Belgian Trappist beer. The taxonomy of the genus Brettanomyces has been debated since its early discovery and has seen many reclassifications over the years. Early classification was based on a few species that reproduced asexually (anamorph form) through multipolar budding. Shortly after, the formation of ascospores was observed and the genus Dekkera, which reproduces sexually (teleomorph form), was introduced as part of the taxonomy. The current taxonomy includes five species within the genera of Dekkera/Brettanomyces. Those are the anamorphs Brettanomyces bruxellensis, Brettanomyces anomalus, Brettanomyces custersianus, Brettanomyces naardenensis, and Brettanomyces nanus, with teleomorphs existing for the first two species, Dekkera bruxellensis and Dekkera anomala. The distinction between Dekkera and Brettanomyces is arguable, with Oelofse et al. (2008) citing Loureiro and Malfeito-Ferreira from 2006 when they affirmed that current molecular DNA detection techniques have uncovered no variance between the anamorph and teleomorph states. Over the past decade, Brettanomyces spp. have seen an increasing use in the craft-brewing sector of the industry, with a handful of breweries having produced beers that were primarily fermented with pure cultures of Brettanomyces spp. This has occurred out of experimentation, as very little information exists regarding pure culture fermentative capabilities and the aromatic compounds produced by various strains. Dekkera/Brettanomyces spp. have been the subjects of numerous studies conducted over the past century, although a majority of the recent research has focused on enhancing the knowledge of the wine industry. Recent research on eight Brettanomyces strains available in the brewing industry focused on strain-specific fermentations and identified the major compounds produced during pure culture anaerobic fermentation in wort. Wine<unk>  in a bottle during sparkling wine production at Schramsberg Vineyards, Napa<unk>  is used in winemaking, where it converts the sugars present (glucose and fructose) in grape juice (must) into ethanol.<unk>  is normally already present on grape skins. Fermentation can be done with this endogenous "wild<unk> ", but this procedure gives unpredictable results, which depend upon the exact types of<unk>  species present. For this reason, a pure<unk>  culture is usually added to the must; this<unk>  quickly dominates the fermentation. The wild<unk> s are repressed, which ensures a reliable and predictable fermentation. Most added wine<unk> s are strains of S. cerevisiae, though not all strains of the species are suitable. Different S. cerevisiae<unk>  strains have differing physiological and fermentative properties, therefore the actual strain of<unk>  selected can have a direct impact on the finished wine. Significant research has been undertaken into the development of novel wine<unk>  strains that produce atypical flavour profiles or increased complexity in wines. The growth of some<unk> s, such as Zygosaccharomyces and Brettanomyces, in wine can result in wine faults and subsequent spoilage. Brettanomyces produces an array of metabolites when growing in wine, some of which are volatile phenolic compounds. Together, these compounds are often referred to as "Brettanomyces character", and are often described as "antiseptic" or "barnyard" type aromas. Brettanomyces is a significant contributor to wine faults within the wine industry. Researchers from the University of British Columbia, Canada, have found a new strain of<unk>  that has reduced amines. The amines in red wine and Chardonnay produce off-flavors and cause headaches and hypertension in some people. About 30% of people are sensitive to biogenic amines, such as histamines. Baking<unk> , the most common one being S. cerevisiae, is used in baking as a leavening agent, where it converts the food/fermentable sugars present in dough into the gas carbon dioxide. This causes the dough to expand or rise as gas forms pockets or bubbles. When the dough is baked, the<unk>  dies and the air pockets "set", giving the baked product a soft and spongy texture. The use of potatoes, water from potato boiling, eggs, or sugar in a bread dough accelerates the growth of<unk> s. Most<unk> s used in baking are of the same species common in alcoholic fermentation. In addition, Saccharomyces exiguus (also known as S. minor), a wild<unk>  found on plants, fruits, and grains, is occasionally used for baking. In breadmaking, the<unk>  initially respires aerobically, producing carbon dioxide and water. When the oxygen is depleted, fermentation begins, producing ethanol as a waste product; however, this evaporates during baking. A block of compressed fresh<unk>  It is not known when<unk>  was first used to bake bread. The first records that show this use came from Ancient Egypt. Researchers speculate a mixture of flour meal and water was left longer than usual on a warm day and the<unk> s that occur in natural contaminants of the flour caused it to ferment before baking. The resulting bread would have been lighter and tastier than the normal flat, hard cake. Active dried<unk> , a granulated form in which<unk>  is commercially sold Today, there are several retailers of baker's<unk> ; one of the earlier developments in North America is Fleischmann's<unk> , in 1868. During World War II, Fleischmann's developed a granulated active dry<unk>  which did not require refrigeration, had a longer shelf life than fresh<unk> , and rose twice as fast. Baker's<unk>  is also sold as a fresh<unk>  compressed into a square "cake". This form perishes quickly, so must be used soon after production. A weak solution of water and sugar can be used to determine whether<unk>  is expired. In the solution, active<unk>  will foam and bubble as it ferments the sugar into ethanol and carbon dioxide. Some recipes refer to this as proofing the<unk> , as it "proves" (tests) the viability of the<unk>  before the other ingredients are added. When a sourdough starter is used, flour and water are added instead of sugar; this is referred to as proofing the sponge. When<unk>  is used for making bread, it is mixed with flour, salt, and warm water or milk. The dough is kneaded until it is smooth, and then left to rise, sometimes until it has doubled in size. The dough
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