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Muffin

Muffins

A muffin is an  an American English name for a type of bread that is baked in small portions. Many forms are somewhat like small cakes or c cupcakes  upcakes in shape, although they usually are not as sweet as cupcakes and generally lack frosting. Savory varieties, such as cornbreadmuffins, cornbreadmuffins, also exist. They generally fit in the palm of an adult hand, and are intended to be consumed by an individual in a single sitting. Outside the United States of America, muffin can also refer to a disk-shaped muffin, usually called an English Muffin outside of England. As American-style muffins are also sold in Commonwealth countries, the term muffin can refer  to either product, with the context usually making clear which is meant. There are many varieties and flavors of muffins made with a specific ingredient such as blueberries, blueberries, chocolate chips, cucumbers, cinnamon,, pumpkin, date date,, nut nut,, lemon lemon,, banana banana,, orange, peach, strawberry, boysenberry, almo cucumbers, raspberry,cinnamon nd,, and carrot nd carrot,, baked into the muffin. Muffins are often eaten for breakfast; alternatively, they may be served for tea for tea  or at other meals. History

Chocolate chip muffins baking in an  an oven

Recipes for muffins, in their yeast-free "American" form, are common in 19th century American cookbooks.[1][2] Recipes for  yeast-based muffins, which were sometimes called "common muffins" or "wheat muffins" in 19th century American cookbooks, can be found in much older  cookbooks. cookbooks. A somewhat odd combination of circumstances in the 1970s and 1980s led to significant changes in what had been a rather simple, if not prosaic, food. The decline in home-baking, the  the health food  food movement, the rise of the specialty food coffee  trend all contributed to the creation of a new standard of muffin.[citation needed ] shop, and the  the gourmet coffee Preservatives in muffin mixes led to the expectation that muffins did not have to go stale within hours of baking, but the resulting muffins were not a taste improvement over homemade.[citation needed ] On the other hand, the baked muffin, even if  from a mix, seemed almost healthy compared to the fat-laden alternatives of doughnuts and Danish pastry. "Healthy" grains  and such "natural" things as yogurt  yogurt and variousvegetables variousvegetables  evolved rapidly. But for  muffin recipes using  using whole grains "healthy" muffins to have any shelf-life without artificial preservatives, the the  sugar  and fat content needed to be increased, to the point where the "muffins" are almost indistinguishable from  from cupcakes. The rising market for gourmet snacks to accompany gourmet coffees resulted in fancier concoctions in greater bulk than the original, modestly sized corn muffin. The marketing trend toward larger portion sizes also resulted in new muffin pan types for home-baking, not only for  increased size. Since the area ratio of muffin top to muffin bottom changed considerably when the traditional small round exploded into a giant mushroom, consumers became more aware of the difference between the soft texture of tops, allowed to rise unfettered, and rougher, tougher bottoms restricted by the pans. There was a brief foray into pans that Seinfeld made made reference to could produce "all-top" muffins, i.e., extremely shallow, large-diameter cups. The TV sitcom  sitcom Seinfeld  Tops" " episode in which the character Elaine character  Elaine Benes  Benes co-owns a bakery named "Top o' the Muffin to this in the "The " The Muffin Tops  You!" that sold only the muffin tops. Along with the increasing size of muffins is a contrary trend of extremely small muffins. It is now very common to see muffin pans or premade muffins that are only one or two inches in diameter. Types of muffins

English muffin Main article: Muffin (English) The  English muffin, which predates the American muffin,[citation needed ] is a type of light bread leavened with yeast. It is us ually The two, toasted toasted  and served baked in a flat-sided disc-shaped tin, typically about 8 cm in  in diameter . Muffins are usually split in two, 

 

a toasting fork. Muffins can also be with  butter . Traditionally muffins were toasted in front of an open fire or stove, using a  with eaten cold with a hot drink at c offee shops and diners, or split and filled similar to a sandwich (most famously McMuffin). the  the McDonald's chain's McMuffin). In her  Boston Cooking-School Cook Book , Fannie Farmer  gave recipes for both types of muffins, adding instructions for a rings  on version that is nearly identical to today's "English muffin". Here the raised-muffin mixture was cooked in  in muffin rings a griddle  griddle and flipped to brown both sides, producing a grilled muffin. Farmer indicated this was a useful method when baking in an oven was not p ractical. Corn muffin cornmeal  are popular in the United States. Though corn muffins can simply be muffin Muffins made from cornmeal shaped  cornbread, shaped cornbread, corn muffins tend to be sweeter. Similar to the pan variety, corn muffins can be eaten with butter or as a side dish with stews or chili. Muffin cups

A blueberry  blueberry muffin in a paper muffin cup.

metal,[3] with scallop-pressed edges, giving the muffin a round cup shape. Muffin cups are round sheets of  paper , foil or metal, They are used in the baking of muffins to line the bottoms of muffin tins, to facilitate the easy removal of the finished muffin from the tin. The advantage to cooks is easier removal and cleanup, more precise form, and moister muffins; however, using them will prevent a crust. Pie A slice of an  an  apple pie

A pie is a baked dish which is usually made of a  a pastry  pastry dough casing that covers or completely contains a filling of  or savouryingredients. various sweet or savoury Pies are defined by their crusts. A filled  filled pie pie (also single-crust  single-crust or  or bottom-crust  bottom-crust ), ), has pastry lining the baking dish, and the filling is placed on top of the pastry, but left open. A top-crust  top-crust pie, pie, which may also be called a  a cobbler , has the filling in the bottom of the dish and the filling covered with a pastry or other covering before baking. A two-crust  two-crust pie pie has the filling completely enclosed in the pastry shell.  shell. Flaky pastry  pastry is a typical kind of pastry used for pie crusts, but many things can be and crumbs. crumbs. used, including baking powder biscuits, mashed potatoes, and  Pies can be a variety of sizes, ranging from bite-size to ones designed for multiple servings.

History vegetables.The need for nutritious, easy-to-store, easy-to-carry, and long-lasting foods Homemade  meat pie  Homemade pie with with  beef and beef andvegetables sea,, was initially solved by taking live food along with a butcher  butcher or  or  cook. cook. However, this on long journeys, in particular at  at sea took up additional space on what were either horse either  horse-powered -powered treks or small ships, reducing the time of travel before hunter-foraging. additional food was required. This resulted in early armies  armies adopting the style of hunter-foraging

baking  of processed cereals including the creation of  flour , provided a more reliable source of  The introduction of the  the baking food. Egyptian  Egyptian sailors carried a flat brittle  millet  bread called dhourra cake, while the Romans  Romans had brittle  bread  bread loaf  of  millet buccellum.[1] a biscuit  biscuit called buccellum. The first pies appeared around 9500 BC, in the Egyptian Neolithic  Neolithic period or New or New Stone Age, when the use of stone tools shaped by polishing or grinding became common, the domestication of plants and animals, the establishment of  permanent villages, and the practice of crafts such as  as pottery and  weaving. Early pies were known pottery  and ground oats barley. These galettes developed into a as galettes, wrapping honey honey  as a treat inside a cover of ground  oats,, wheat wheat,, rye rye  or barley form of early sweet  sweet pastry  pastry or desserts the  Pharaoh Ramesses II, who or desserts,, evidence of which can be found on the tomb walls of the

 

ruled from 1304 to 1237 BC, located in the  the  Valley of the Kings.[2] Sometime before 2000 BC, a recipe for chicken pie was written on a tablet in  in Sumer .[3] With the knowledge transferred to the Ancient Greeks, Greeks, historians believe that the Greeks originated pie pastry. Then a flour-water paste (add fat, and it becomes  becomes pastry),[4] wrapped around meat, served to: cook the meat; seal in the juices; and provide a lightweight sealed holder for long sea journeys. This transferred the knowledge to the the  Romans who, having conquered parts of Northern Europe and southern  southern  Spain  Spain were far more adept at using salt and spices to preserve and flavour their meat. meat.[2] The 1st century Roman cookbook Apicius cookbook  Apicius  make various mention of various recipes which involve a pie case. case .[5]By 160 BC, Roman statesman  statesman Marcus Porcius Cato (234-149 BC) who wrote  wrote De Agri Cultura Agri Cultura, notes the recipe for the most popular  Placenta.. Also called libum by the Romans, it was more like a modern day day  cheesecake on a pastry base, pie/cake called Placenta often used as an offering to the gods. With the development of the Roman Empire and its efficient road transport, pie cooking spread throughout  throughout Europe.[2] Pies remained as a core staple of diet of traveling and working peoples in the colder northern European countries, with regional variations based on both the locally grown and available meats, as well as the locally farmed cereal crop. The  Cornish pasty  The pasty is an excellent adaptation of the pie to a working man's daily food needs. needs.[2] Medieval cooks were often restricted in cooking forms they were able to use, having restricted access to ovens due to their costs of construction and need for abundant supplies of fuel. Pies could be easily cooked over an open fire, while partnering with a baker allowed them to cook the filling inside their own locally defined casing. The earliest pie-like recipes basket  or  box box)), with straight sealed sides and a top; open top pies were refer to coffyns (the word actually used for a  a  basket referred to as traps.This may also be the reason why early recipes focus on the filling over the surrounding case, with the partnership development leading to the use of reusable earthenware pie cases which reduced the use of expensive flour.[6] The first reference to "pyes" as food items appeared in England  England (in a  a Latin  Latin context) as early as the 12th century, but no unequivocal reference to the item with which the article is concerned is attested until the 14th century (Oxford English Dictionary  sb pie sb pie)).[2] Song birds at the time were a fine delicacy, and protected by Royal Law. At the coronation of eight-year old English  English King Henry VI  VI (1422–1461) in 1429, "Partryche and Pecock enhackyll" pie was served, consisting of cooked  peacock  mounted in cooked peacock its skin on a peacock filled pie. Cooked birds were frequently placed by European royal cooks on top of a large pie to identify its contents, leading to its later adaptation in pre-Victorian times as a porcelain ornament to release of steam and identify a good pie.[2] The  Pilgrim fathers and early settlers brought their pie recipes with them to  The to  America, America, adapting to the ingredients and techniques available to them in the New World. Their first pies were based on berries and fruits pointed out to them by Americans..[2] Pies allowed colonial cooks to stretch ingredients and also used round shallow pans to the  the Native North Americans literally "cut corners," and create a regional variation of shallow pie.[7] Regional variations

Apple pie crust pies with fillings such as steak, cheese, Meat pies  cheese,  steak and kidney kidney,, minced beef , or chicken or chicken  and  and mushroom are popular in Australiaand and New Zealand as take-away snacks. They are also served with chips chips  as an alternative the  the United Kingdom,[8] Australia chips  at British chip shops. to fish and chips Pot pies  pies with a flaky crust and bottom are also a popular American dish, typically with a filling of meat (particularly beef, chicken or turkey), gravy, and mixed vegetables (potatoes, carrots and peas). Frozen pot pies are often sold in individual serving size.

 

as  pie à la mode . Many sweet pies are Fruit pies may be served with a scoop of ice cream, a style known in North America as served this way. Cream, as well as sour cream, is also sometimes considered to be an à la mode serving method as well. [citation needed ]

 Apple pie  pie is a traditional choice, though any pie with sweet fillings may be served à la mode. mode. This combination,

and possibly the name as well, is thought to have b een popularized in the mid-1890s in the United States. States.[9] Pie throwing

Main article: Pieing  Cream filled or topped pies are favorite props for humor. Throwing a pie in a person's face has been a staple of film in Mr. Flip  Flip in 1909. 1909.[10] More recently, pieing has also become a political act. comedy since  since Ben Turpin  Turpin received one in  Types of pies

Main article: List of pies Savory pies Chicken Pie A traditional Cornish  Cornish pasty  pasty filled withsteak withsteak and vegetables



Bacon and egg pie



Butter pie



Chicken and mushroom pie



Corned beef pie



Cottage pie (or shepherds' pie)



Game pie



Fish pie



Hom Homity ity pie



Meat pie



Pasty



Pizza pie



Pork pie



Pot pie



Quiche



Scotch pie



Curry pie



Sta Stargaz rgazy y pie



Steak pie



Steak and kidney pie

Sweet pies Pumpkin pie

Blackberry pie  pie and ice cream

Some of these pies are pies in name only, such as the  the Boston cream pie, pie, which is a  a cake. cake. Many fruit and berry pies are very similar, varying only the fruit used in filling. Fillings for sweet or fruity are often mixed, such as strawberry rhubarb pie.

 



Apple pie



Ban Banoffe offee e pie



Blackberry pie



Blueberry pie



Buk o pie



Cherry pie



Chess pie



Cream pie



Custard pie



Fried pie



Key lime pie



Lemon meringue pie



Mince pie



Pecan pie



Pumpkin pie



Rhubarb pie



Shoofly pie—a pie filled with molasses



Strawberry pie



Sugar pie



Sweet potato pie

 Yeast

Yeast

Yeast of the species Saccharomyces species  Saccharomyces cerevisiae

Scientific classification

Domain:

Eukaryota

Kingdom:

Fungi

Phyla and Subphyla

Ascomycota 

Saccharomycotina (true yeasts)



Taphrinomycotina 

Schizosaccharomycetes(fissio (fissio Schizosaccharomycetes n yeasts)

 

Basidiomycota 

Agaricomycotina 



Tremellomycetes

Pucciniomycotina 

Microbotryomycetes

micro-organisms  classified in the   Yeasts are  are  eukaryotic  eukaryotic micro-organisms the kingdom  kingdom Fungi, with 1,500  1,500 species  species currently described[1] estimated asexually  by by  mitosis mitosis,, and many do so via an asymmetric division to be only 1% of all fungal species. species .[2] Most reproduce asexually process called budding. Yeasts are unicellular, although some species with yeast forms may become multicellular through false hyphae, as seen in most  molds.. or false most  molds the formation of a string of connected budding cells known as pseudohyphae, or  [3]

  Yeast Yeast size can vary greatly depending on the species, typically measuring 3–4 3–4  µm  µm in  in diameter , although some yeasts

can reach over 40 µm. [4] By  By fermentation the yeast species Saccharomyces cerevisiae  cerevisiae converts and alcohols - for  converts  carbohydrates  carbohydrates to carbon dioxide  dioxide and  thousands of years the carbon dioxide has been used in in  baking  baking and the alcohol in  in alcoholic beverages.[5] It is also biology  research, and is one of the most thoroughly extremely important as a  a model organism  organism in modern  modern cell biology researched eukaryotic  eukaryotic microorganisms. Researchers have used it to gather information about the biology of the albicans,, are are  opportunistic eukaryotic cell and ultimately human biology. biology .[6] Other species of yeast, such as Candida albicans pathogens  and can cause  pathogens in microbial fuel cause infections in humans. Yeasts have recently been used to generate electricity in  cells,[7] and produce ethanol for the biofuel industry. cells,  Yeasts do not form a single taxonomic or phylogenetic or phylogenetic grouping. The term "yeast" is often taken as for Saccharomyces cerevisiae, cerevisiae,[8] but the phylogenetic diversity of yeasts is shown by their placement in two a synonym  synonym for Saccharomyces separate  phyla, the Ascomycota and the Basidiomycota. The budding yeasts ("true yeasts") are classified in separate the  the order  Saccharomycetales.[9] History

See also:  also: History of wine wine  and  History of beer  foam,, English  gist , gyst , and from the  Indo-European  root yes- , meaning boil , foam The word "yeast" comes to us from  from Old English the  Indo-European or  or bubble bubble..[10] Yeast microbes are probably one of the earliest domesticated organisms. People have used yeast for  fermentation and baking throughout history. Archaeologists digging in Egyptian ruins found early grinding stones and baking chambers for yeasted bread, as well as drawings of 4,000-year-old bakeries and breweries.[11] In 1680, the  the Dutch naturalist naturalist  Anton van Leeuwenhoek  Leeuwenhoek first  first microscopically microscopically  observed yeast, but at the time did not consider them to organisms ms, but rather globular structures. 1857, French microbiologist microbiologist  Louis Pasteur  proved in the paper  beliving beliving organis structures.[12] In 1857,  "Mémoire sur l a fermentation alcoolique" alcoolique" that alcoholic fermentation was conducted by living yeasts and not by a broth, cell growth growth  could be increased, but chemical catalyst. catalyst.[11][13] Pasteur showed that by bubbling oxygen into the yeast broth,  effect". ". fermentation was inhibited – an observation later called the "Pasteur "Pasteur effect cerevisiae, so called top By the late 18th century, two yeast strains used in brewing had been identified: Saccharomyces cerevisiae, fermenting  yeast, and  fermenting carlsbergensis,, bottom fermenting fermenting  yeast. S. cerevisiae has been sold commercially by the Dutch and S. carlsbergensis for bread making since 1780; while around 1800, the Germans started producing S. cerevisiae in the form of cream. In 1825 a method was developed to remove the liquid so the yeast could be prepared as solid blocks. blocks .[14] The industrial production of yeast blocks was enhanced by the introduction of the filter press  press in 1867. In 1872, Baron Max de Springer developed a manufacturing process to create granulated yeast, a technique that was used until the first World War .[15] In the United States, naturally occurring airborne yeasts were used almost exclusively until commercial yeast was marketed at the  the Centennial Exposition Exposition  in 1876 in Philadelphia, where  where Charles L. Fleischmann exhibited the product and a process to use it, as well as serving the resultant baked bread. Nutrition and growth

 

 Yeasts are chemoorganotrophs, as they use  use  organic compounds  compounds as a source of energy and do not require sunlight to glucose  and fructose,, or disaccharides such andfructose grow. Carbon is obtained mostly from hexose sugars, such as glucose and  maltose maltose.. Some species can metabolize  metabolize pentose  pentose sugars like ribose,[16] alcohols, and organic acids. Yeast as as  sucrose and alcohols, and  respiration tion (obligate aerobes), or are anaerobic, but also have aerobic species either require oxygen for aerobiccellular aerobiccellular respira methods of energy production (facultative anaerobes anaerobes)). Unlike bacteria, bacteria, there are no known yeast species that grow only anaerobically (obligate (obligate anaerobes). anaerobes). Yeasts grow best in a neutral or slightly acidic pH environment.  Yeasts vary in what temperature range they grow best. For example, Leucosporidium frigidum grows at -2 to 20 °C (28 to 68 °F), Saccharomyces telluris at 5 to 35 °C (41 to 95 °F) and Candida slooffi at at 28 to 45 °C (82 to 113 °F). °F).[17] The cells can survive freezing under certain conditions, with viability decreasing over time. media  or in liquid  broths.. Common media used for the  Yeasts are generally grown in the laboratory on solid growth media liquid broths cultivation of yeasts include  include potato dextrose agar  (PDA) or  potato dextrose broth, Wallerstein Laboratories nutrient peptone  dextrose  dextrose agar (YPD), and yeast mould agar or broth (YM). Home brewers who cultivate yeast (WLN) agar , yeast peptone andagar  as a solid growth medium. The antibiotic  antibiotic cycloheximide is sometimes frequently use dried malt extract  extract (DME) andagar  added to yeast growth media to inhibit the growth of Saccharomyces of Saccharomyces yeasts and select for wild/indigenous yeast species. This will change the yeast process. The appearance of a white, thready yeast, commonly known as kahm yeast, is often a byproduct of the lactofermentation (or pickling) of certain vegetables, usually the result of exposure to air. Although harmless, it can give pickled vegetables a bad flavour and so must be re moved regularly during fermentation.[18] Ecology

 Yeasts are very common in the environment, and are often isolated from sugar-rich material. Examples include naturally grapes,, apples  apples or peaches), peaches), and exudates from plants (such as occurring yeasts on the skins of fruits and be rries (such as as  grapes The ecological  ecological function plant saps or cacti). Some yeasts are found in association with soil and insects. insects .[19][20] The  biodiversity  of yeasts are relatively unknown compared to those of other microorganisms other  microorganisms..[21] Yeasts,  Yeasts, and  biodiversity and rubra, Torulopsis Torulopsis  and including Candida albicans, albicans, Rhodotorula rubra, and  Trichosporon cutaneum, have been found living in  Yeasts are also present in the  the  gut flora  flora of mammals and some between people's toes as part of their  skin flora. flora.[22] Yeasts insects[23] and even deep-sea environments host an array of yeasts. yeasts .[24][25] An Indian study of seven bee species and 9 plant species found 45 species from 16 genera colonise the nectaries of  flowers and honey stomachs of bees. Most were members of the Candida  Candida genus; the most common species in honey stomachs was Dekkera intermedia and in flower nectaries,  nectaries, Candida blankii   .[26] Yeast colonising nectaries of the  the  stinking hellebore  have been found to raise the temperature of the flower, which may aid in attracting pollinators by increasing the hellebore [21][27]

 A black yeast has been recorded as a partner in a complex relationship evaporation of  volatile organic compounds. compounds. between  ants, between ants, their  their mutualistic mutualistic fungus, a fungal  parasite  of the fungus and a  fungal parasite a bacterium  bacterium that kills the parasite. The yeast have a negative effect on the bacteria that normally produceantibiotics produce antibiotics  to kill the parasite and so may affect the ants' health by allowing the parasite to spread.[28] Reproduction

 

The yeast cell's life cycle: 1. Budding 2. Conjugation 3. Spore

See also:  also: Mating of yeast   Yeasts, like all fungi, may have asexual and sexual sexual  reproductive cycles. The most common mode of vegetative growth in budding..[29] Here a small bud (also known as a  a  bleb), bleb), or daughter cell, is formed on the yeast is asexual reproduction by  by budding parent cell. The nucleus  nucleus of the parent cell splits into a daughter nucleus and migrates into the daughter cell. The bud continues to grow until it separates from the parent cell, forming a new cell.[30] Some yeasts, budding.[29] including Schizosaccharomyces pombe, reproduce by  by fission  fission instead of budding. Under high stress conditions,  conditions, haploid haploid  cells will generally die; under the same conditions, however, however,  diploid  diploid cells can meiosis)) and producing a variety of haploid spores, which can go on undergo sporulation, entering sexual reproduction (meiosis the diploid. diploid.[31] to mate  mate (conjugate), reforming the  Some pucciniomycete yeasts, particularly species of Sporidiobolus of Sporidiobolus  and and  Sporobolomyces Sporobolomyces  produce aerially dispersed, asexual ballistoconidia.[32] Uses

The useful physiological properties of yeast have led to their use in the field of  biotechnology. Fermentation of sugars by yeast is the oldest and largest application of this technology. Many types of yeasts are used for making many ermentation; rmentation; yeast in in  wine  wine fermentation and foods: baker's yeast  yeast in bread  bread production; brewer's yeast in beerf e So-called red rice yeast yeast  is actually a  a mold, mold, Monascus purpureus. purpureus. Yeasts include some of the most for xylitol for xylitol production production..[33] So-called  widely used  used model organisms  organisms for  genetics  genetics and and  cell biology. Alcoholic beverages Alcoholic beverages  beverages  that contain  beverages are defined as  as beverages contain ethanol (C2H5OH). This ethanol is almost always produced the metabolism  metabolism of  of carbohydrates carbohydrates  by certain species of yeast under anaerobic or low-oxygen conditions. by  by fermentation – the  wine,, beer , or distilled or distilled spirits spirits  all use yeast at some stage of their production. A d istilled beverage is a Beverages such as wine distillation.. Carbohydrate-containing plant material is fermented by beverage containing ethanol that has been purified by  by distillation yeast, producing a dilute solution of ethanol in the process. Spirits such as  as  whiskey  whiskey and rum are prepared by distilling these dilute solutions of ethanol. Components other than ethanol are collected in the condensate, including water,  water, esters esters,,  flavour of the beverage. and other alcohols other alcohols,, which account for the flavour of Beer  Beer being fermented by brewers yeast

fermenting") ") and "bottom cropping" (or "bottom-fermenting "bottom-fermenting"). "). Brewing yeasts may be classed as "top cropping" (or "top " top fermenting [34]

 Top cropping yeasts are so called because they form a foam at the top of the wort during fermentation. An example of a

top cropping yeast is Saccharomyces cerevisiae, cerevisiae, sometimes called an "ale yeast". yeast" .[35] Bottom cropping yeasts are typically used to produce  produce lager -type beers, though they can also produce ale-type beers. These yeasts ferment well at low carlsbergensis. temperatures. An example of bottom cropping yeast is  is Saccharomyces pastorianus, formerly known as S. carlsbergensis. Decades ago, taxonomists reclassified S. carlsbergensis (uvarum) as a member of S. cerevisae, noting that the only distinct difference between the two is metabolic. Lager strains of S. cerevisae secrete an enzyme called melibiase, allowing it to hydrolyse the disaccharide melibiose into more fermentable monosaccharides. Top cropping and bottom cropping, cold fermenting and warm fermenting distinctions are largely generalizations used to by the laymen to communicate to the general public. For more on the taxonomical differences, see Terrance M. Dowhanick, B.SC., PH. D "Yeast - Strains and Handling Techiques" in The Practical Brewer, a publication of the Master Brewers Association of the Americas.

 

The most common top cropping brewer's yeast, S. cerevisiae, cerevisiae, is the same species as the common baking yeast. [36]

 Brewer's yeast is also very rich inessential in essential minerals and the  the B vitamins vitamins  (except B12). B12).[37] However, baking and brewing

yeasts typically belong to different strains, cultivated to favour different characteristics: baking yeast strains are more aggressive, to carbonate  carbonate dough dough  in the shortest amount of time possible; brewing yeast strains act slower, but tend to produce fewer off-flavours and tolerate higher alcohol concentrations (with some strains, up to 22%). of Lambic  Lambic  and specialty sour  Dekkera /Brettan /Brettanomyces omyces is a genus of yeast known for their important role in the production of  ales,, along with the secondary conditioning of a particular Belgian Trappist beer [38]. The taxonomy of the genus ales Brettanomyces has been debated since its early discovery and has seen many re-classifications over the years. Early classification was based on a few species that reproduced asexually (anamorph form) through multipolar budding  budding [39].  Shortly after, the formation of ascospores was observed and the genus Dekkera, which reproduces sexually (teleomorph form), was introduced as part of the taxonomy  taxonomy  [40]. The current taxonomy includes five species within the genera of  Brettanomyces omyces anomal anomalus us,, Brettanomyces Dekkera/Brettanomyces. Those are the anamorphs  anamorphs Brettanomyces bruxellensis, bruxellensis,Brettan custersianus,, Brettanomyces naardenensis, and  custersianus and Brettanomyces nanus, with teleomorphs existing for the first two species, Dekkera bruxellensis andDekkera andDekkera anomala

[41]

. 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 primary 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 8 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. wort.[42] Wine Fermentation (wine)  Yeast is used in winemaking, where it converts the sugars present in  into ethanol ethanol.. Yeast is normally in  grape juice  juice (must) must) into  already present on grape skins (the white powder called "the bloom"). Fermentation can be done with this endogenous "wild yeast,"[43] but this procedure gives unpredictable results, which depend upon the exact types of yeast species present. For this reason, a pure yeast culture is usually added to the must; must; this yeast quickly dominates the fermentation. The wild yeasts are repressed, which ensures a reliable and predictable fermentation. fermentation .[44] Most added wine yeasts are strains of  S. cerevisiae cerevisiae,, though not all strains of the species are suitable. suitable.[44] Different S. cerevisiae yeast strains have differing physiological and fermentative properties, therefore the actual strain of yeast selected can have a direct impact on the finished wine. wine .[45] Significant research has been undertaken into the development of novel wine yeast strains that produce atypical flavour profiles or increased complexity in wines. wines.[46][47] The growth of some yeasts, such as Zygosaccharomyces Zygosaccharomyces  and and  Brettanomyces, in wine can result in  in  wine faults and Brettanomycesproduces produces an array of  metabolites when growing in wine, some of which are subsequent spoilage.[48] Brettanomyces volatile phenolic phenolic  compounds. Together, these compounds are often referred to as "Brettanomyces " Brettanomyces character", and are often described as "antiseptic "antiseptic" or "barnyard" type aromas. Brettanomyces is a significant contributor to  to wine faultswithin faultswithin the wine industry. industry.[49] Researchers from  from University of British Columbia , Canada Canada,, have found a new strain of yeast that has reduced amines. amines. The and Chardonnay  Chardonnay produce off-flavors and cause headaches and hypertension in some people. About 30 amines in  in red wine  wine and  histamines..[50] percent of people are sensitive to biogenic amines, such as  as histamines Baking  Yeast, most commonly S. cerevisiae, cerevisiae, is used in  in  baking baking  as a  a leavening agent, where it converts fermentable  sugars sugars  present in dough  the  the fermentable dough into the gas carbon dioxide. dioxide. This causes the dough to expand or rise as gas

 

forms pockets or bubbles. When the dough is baked, the yeast 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 yeasts. Most yeasts used in baking are of the same species common in alcoholic fermentation. Additionally, Saccharomyces exiguus (also known as S. minor ), ), a wild yeast found on plants, fruits, and grains, is occasionally used for baking. Sugar and  and vinegar  provide the best conditions for yeast to ferment. In bread making, the yeast initially respires aerobically, producing carbon dioxide and water. When the oxygen is depleted,  depleted, anaerobic respiration  begins, producing ethanol as a waste product; however, this evaporates during baking.[51] respiration It is not known when yeast was first used to bake bread. The first records that s how this use came from Ancient Egypt. [52]

 Researchers speculate a mixture of flour meal and water was left longer than usual on a warm day and the yeasts 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 yeast, a granulated form in which yeast is commercially sold

Today, there are several retailers of  baker's yeast; one of the best-known in North America is is  Fleischmann’s Yeast, Yeast, which ld War II , Fleischmann's developed a  a  granulated granulated  active dry yeast, which did not require was developed in 1868. DuringWor DuringWorld refrigeration and had a longer  shelf life than fresh yeast. The company created yeast that would rise twice as fast, reducing baking time. Baker's yeast yeast  is also sold as a fresh yeast compressed into a square "cake". This form perishes quickly, and must therefore be used soon after production. A weak solution of water and sugar can be used to determine if yeast is expired. In the solution, active yeast will foam and bubble as it ferments the sugar into ethanol and carbon dioxide. Some recipes refer to this as proofing the yeast as it "proves" (tests) the viability of the yeast before the other ingredients are added. When using a  a sourdough starter, flour and water are added instead of sugar; this is referred to as proofing the sponge. When yeast 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. Some bread doughs are kn ocked back after one rising and left to rise again. A longer rising time gives a better flavour, but the yeast can fail to raise the bread in the final stages if it is left for too long initially. The dough is then shaped into loaves, left to rise until it is the correct size, and then baked. Dried yeast is usually specified for use in a bread machine machine;; however, a (wet) sourdough starter can also work. Bioremediation Some yeasts can find potential application in the field of  bioremediation bioremediation.. One such yeast, Yarrowia lipolytica, lipolytica, is known to   TNT (an explosive material), material),[54] and other hydrocarbons other hydrocarbons, such as alkanes, degrade  palm oil  degrade oil mill effluent, effluent,[53] alkanes, fatty acids, fats fats  and oils oils..[55] It can also tolerate high concentrations of salt and andheav heavy y meta metals ls,,[56] and is being investigated for its potential as a heavy metal biosorbent. biosorbent.[57] Industrial ethanol production The ability of yeast to convert sugar into  into  ethanol  ethanol has been harnessed by the biotechnology biotechnology  industry to produce  produce ethanol fuel.. The process starts by milling a feedstock, such as fuel as  sugar cane, cane, field corn corn,, or other cereal other cereal grains, grains, and then adding amylase  enzymes, to break down the starches into complex sugars. A glucoamylase is dilute  sulfuric acid, dilute acid, or fungal alpha amylase then added to break the complex sugars down into  into simple sugars. After this, yeasts are added to convert the simple distilled  off to obtain ethanol up to 96% in concentration concentration..[58] sugars to ethanol, which is then  then distilled Saccharomyces yeasts have been genetically engineered to ferment xylose, one of the major fermentable sugars present in  in cellulosic biomasses, biomasses, such as agriculture residues, paper wastes, and wood chips chips..[59][60] Such a development means ethanol can be efficiently produced from more inexpensive feedstocks, making cellulosic ethanol fuel a more fuels..[61] competitively priced alternative to gasolinefuels Nonalcoholic beverages A Kombucha culture fermenting in a jar  Root beer  and other sweet carbonated beverages can be prod uced using the same methods as beer, except the fermentation is stopped sooner, producing carbon dioxide, but only trace amounts of alcohol,

 

and a significant amount of sugar is left in the drink. Kvass inEastern Kvass,, a fermented drink made from  from rye, is popular inEast ern Euro Europe pe; with  acetic acid bacteria is used in the preparation it has a recognizable, but low alcoholic content. Yeast in  in symbiosis  symbiosis with include:  Brettanomyces of kombucha of kombucha,, a fermented sweetened  sweetened tea. tea. Species of yeast found in the tea can v ary, and may include: bruxellensis,, Candida stellata, bruxellensis stellata,Schizosaccharomyces pombe, Torulaspora delbrueckii  and and  Zygosaccharomyces bailii . [62]

 Kombucha is a popular beverage in Eastern Europe and someformer some former Soviet republic republics s under the name chajnyj 

grib (Чайный гриб), which means "tea mushroom". Kefir  Kefir and and kumis are made by fermenting milk with yeast and bacteria. [63]

Nutritional supplements See also: Tibicos  Yeast is used in nutritional supplements popular with  with vegans  vegans and the health conscious, where it is often referred to as yeast". ". It is a deactivated yeast, usually S. cerevisiae. cerevisiae. It is an excellent source of protein and vitamins, "nutritional yeast B-complex  vitamins, whose functions are related to metabolism, as well as especially the B-complex minerals  and cofactors required for growth. It is also naturally low in  in  fat and and  sodium. sodium. Some brands of nutritional other  minerals yeast, though not all, are fortified with vitamin B12, which is produced separately by  by bacteria. bacteria. Nutritional yeast, though it has a similar appearance to brewer's yeast, is very different and has a very different taste. Brewer's yeast is a good source of B-complex vitamins but, contrary to some claims, it contains little or no  no vitamin B12.[64] Nutritional yeast has a nutty, cheesy flavor which makes it popular as an ingredient in in  cheese substitutes. It is often used by vegans in place of  Parmesan cheese cheese.. Another popular use is as a topping for popcorn. It can also be used in mashed and fried potatoes, as well as in scrambled eggs. It comes in the form of flakes, or as a yellow powder similar in texture to cornmeal, and can be found in the bulk aisle of most natural food stores. In Australia, it is sometimes sold as "savory yeast flakes". Though "nutritional yeast" usually refers to commercial products, inadequately fed prisoners have used "home-grown" yeast to prevent vitamin deficiency deficiency..[65] Probiotics Some probiotic supplements use the yeast    to maintain and restore the natural flora in the gastrointestinal yeast S. boulardii  tract. S. boulardii has children,[66][67] prevent reinfection boulardii has been shown to reduce the symptoms of acute diarrhea  diarrhea in children, difficile,[68] reduce bowel movements in diarrhea-predominant of Clostridium of Clostridium difficile, diarrhea-predominant  IBS patients patients,,[69] and reduce the incidence traveler's,,[71] and and  HIV/AIDS [72]   associated diarrheas. of antibiotic of antibiotic,,[70] traveler's Aquarium hobby aquarium  hobbyists to generate  in  planted aquariums.[73] A  Yeast is often used by aquarium generate carbon dioxide  dioxide (CO2) to nourish plants in  homemade setup is widely used as a cheap and simple alternative to pressurized CO2 systems. While not as effective as these, the homemade setup is considerably cheaper for less demanding hobbyists. There are several recipes for homemade CO 2, but they are variations of the basic recipe: Baker's yeast, with with  sugar , baking soda  and soda and  water , are added to a plastic bottle. A few drops of vegetable oil at the start reduces surface tension and speeds the release of CO2. This will produce CO2 for about 2 or 3 weeks; the use of a bubble counter determines production. The CO2 is injected in the aquarium via a narrow hose and released through a diffuser that helps dissolve the gas in the water. The CO2 is used by plants in the photosynthesis  photosynthesis process. Science Diagram showing a yeast cell

Several yeasts, particularly S. cerevisiae, cerevisiae, have been widely used in genetics  genetics and cell biology. This is largely humans for the study of  because S. cerevisiae is a simple eukaryoticcell, eukaryoticcell, serving as a  a model for all eukaryotes, including humans  fundamental cellular processes such as the  the cell cycle, DNA replication,recombination recombination,, cell division and and  metabolism metabolism.. Also, yeasts are easily manipulated and cultured in the laboratory, which has allowed for the development of p owerful standard techniques, such as yeast two-hybrid, synthetic genetic array array  analysis and  and tetrad analysis. Many proteins important in

 

homologues  in yeast; these proteins include cell cycle human biology were first discovered by studying their  homologues proteins, signaling proteins, and protein-processing  protein-processing enzymes. On 24 April 1996 S. cerevisiae was announced to be the first eukaryote to have its genome, consisting of 12 million base pairs, fully sequenced as part of the Genome project.[74] At the time, it was the most complex organism to have its full genome sequenced, and took seven years and the involvement of more than 100 laboratories to accomplish accomplish..[75] The second yeast species to have its genome sequenced was  was  Schizosaccharomyces pombe, which was completed in 2002.[76][77] It was the sixth eukaryotic genome sequenced and consists of 13.8 million base pairs.  Yeast extract Main article: Yeast extract  Marmite  and  Marmite and Vegemite, Vegemite, products made from  from yeast extract Marmite and Vegemite have a distinctive dark colour 

 Yeast extract is the common name for various forms of processed yeast p roducts that are used as  as  food additives  or flavours. additives or flavours. They are often used in the same way that  that monosodium glutamate glutamate  (MSG) is used, and like MSG, often contain free glutamic acid. The general method for making yeast extract for food products such and  Marmite  Marmite on a commercial scale is to add salt to a suspension of yeast making the solution hypertonic, as as  Vegemite and digestive  enzymes break their  which leads to the cells shrivelling up. This triggers autolysis, where the yeast's  yeast's digestive ownproteins  down into simpler compounds, a process of self-destruction. The dying yeast cells are then heated to ownproteins complete their breakdown, after which the husks (yeast with thick cell walls which would give poor texture) are separated. Promite  (Australia) Australia); Marmite Marmite,, Bovril and and  Oxo (the (the  United Kingdom, Republic of   Yeast autolysates are used in  in  Vegemite  Vegemite and andPromite Ireland  and South Africa Ireland Africa)); and Cenovis (Switzerland Switzerland). ). Pathogenic yeasts

A photomicrograph  photomicrograph of  Candida albicans albicansshowing showing hyphal outgrowth and other morphological characteristics.

pathogens  where they can cause infection in people with compromised  Some species of yeast are  are opportunistic pathogens compromised immune systems. Cryptococcus neoformans is a significant pathogen of immunocompromised people causing the disease termed cryptococcosis. This disease occurs in about 7–9% of AIDS of  AIDS patients in the USA, and a slightly smaller percentage polysaccharide capsule, which helps to (3–6%) in western Europe. Europe.[78] The cells of the yeast are surrounded by a rigid polysaccharide  prevent them from being recognised and engulfed by  by  white blood cells in the human body.  Yeasts of the  the  Candida  Candida genus are another group of opportunistic pathogens which causes oral and vaginal  vaginal infections infections  in membranes  of humans humans, known as candidiasis.Candida candidiasis.Candida is commonly found as a commensal yeast in the  the mucus membranes and other warm-blooded animals. However, sometimes these same strains can become pathogenic. Here the yeast cells sprout a hyphal outgrowth, which locally penetrates the  the  mucosal membrane, membrane, causing irritation and shedding of the tissues.[78] The pathogenic yeasts of candidiasis in probable descending order of virulence for humans are: C. albicans, albicans, C. tropicalis, C. stellatoidea stellatoidea,, C. glabrata, C. krusei   , C. parapsilosis, C. guilliermondii   , C. viswanathii   , C. lusitaniae and and  Rhodotorula mucilaginosa. [79]Candida glabrata  is the second most common Candida pathogen after C. after C. bloodstream((candidemia). candidemia).[80] the bloodstream albicans,, causing infections of the urogenital tract, and of the  albicans Food spoilage

 Yeasts are able to grow in foods with a low pH, (5.0 or lower) and in the presence of sugars, organic acids and other easily metabolized carbon sources. sources.[81] During their growth, yeasts metabolize some food components and produce metabolic end products. This causes the physical, chemical, and sensible properties of a food to change, and the food is spoiled.[82] The growth of yeast within food products is often seen on their surface, as in cheeses  cheeses or meats or meats,, or by the fermentation of  as syrups and and   jams. jams.[81] The yeast of  sugars in beverages, such as juices as juices,, and semi-liquid products, such as  the  the Zygosaccharomyces Zygosaccharomyces  genus have had a long h istory as a spoilage yeast within the food industry. This is mainly due to

 

ethanol,, acetic acid acid,, sorbic acid,  acid, benzoic acid acid,, the fact that these species can grow in the presence of high high  sucrose, sucrose, ethanol and sulphur dioxide dioxide  concentrations,[83] representing some of the commonly used  used food preservationmethods. Methylene blue is used to test for the presence of live yeast cells.

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