Question 2: What is yeast? Hello! !
One: What is yeast?
The official name of yeast is yeast.
Microbial products produced by fermentation culture with sugar, starch and other industrial and agricultural by-products as raw materials. It is short for yeast. Yeast is the largest microorganism directly consumed by human beings.
Two: the types of yeast:
There are several classification methods for yeast products. According to the different purposes of human consumption and animal feed, it can be divided into edible yeast and feed yeast. Edible yeast is divided into bread yeast, food yeast and medicinal yeast.
Bread yeast can be divided into pressed yeast, active dry yeast and fast active dry yeast.
① Squeezed yeast: a block product with water content of 70 ~ 73% produced by Saccharomyces cerevisiae. Pale yellow, compact structure, easy to crush and strong fuzzing ability. It can be stored at 4℃ for about 65438 0 months and at 0℃ for 2 ~ 3 months. The product was originally obtained by squeezing and dehydrating the centrifuged yeast milk with a plate-and-frame filter press, so it is called squeezed yeast, commonly known as fresh yeast. When fermenting, its dosage is 1 ~ 2% of flour, the fermentation temperature is 28 ~ 30℃, and the fermentation time varies with factors such as yeast dosage, fermentation temperature and sugar content of dough, generally 1 ~ 3 hours.
② Active dry yeast: a dry yeast product containing about 8% moisture and having fermentation ability. Fresh yeast was obtained by using alcohol mother with dry resistance and stable fermentation power, and then it was made by extrusion and drying. The fermentation effect is similar to that of pressed yeast. Products are packed in aluminum foil bags or metal cans filled with vacuum or inert gas (such as nitrogen or carbon dioxide), and the shelf life is from half a year to 1 year. Compared with pressed yeast, it has the advantages of long shelf life, no need for low temperature storage, convenient transportation and use.
③ Fast-active dry yeast: a new fine-grained product (diameter less than 65438±0mm) with fast and efficient fermentation ability. The moisture content is 4-6%. On the basis of active dry yeast, it adopts genetic engineering technology, through special nutrition ratio and strict proliferation and culture conditions, and dries with fluidized bed drying equipment to obtain a highly dry-resistant Saccharomyces cerevisiae strain. Like active dry yeast, the shelf life is longer than 1 year if it is stored in vacuum or filled with inert gas. Compared with active dry yeast, its particles are smaller and its fermentation ability is higher. When in use, it can be directly mixed with flour and added with water to make dough for fermentation, and can be baked into food after fermentation in a short time. This product only appeared in the market in 1970s, and was well received by consumers.
Food yeast is a dry yeast powder or granular product for human consumption, which has no fermentation and reproduction ability. It can be obtained by recycling yeast mud from brewery or by special cultivation and drying according to the requirements of human nutrition. The United States, Japan and some European countries add about 5% edible yeast powder to common foods such as bread, cakes, biscuits and scones to improve the nutritional value of food. Yeast autolysate can be used as an additive for meat, jam, soup, cheese, bread, vegetables and condiments. It is used as a food nutrition enhancer in baby food and health food. The 5'- nucleotide prepared from yeast autolysis extract can be used as an additive to combine with monosodium glutamate to enhance food flavor (see nucleotide seasoning). The concentrated invertase extracted from yeast is used as liquefier for chocolate with square eggs. Extracting lactase from yeast produced in whey can be used to increase sweetness in milk processing, prevent lactose crystallization in whey concentrated solution, and meet the needs of lactose intolerant consumers.
The preparation method and properties of medicinal yeast are the same as those of edible yeast. Because it is rich in protein, vitamins, enzymes and other physiological active substances, it is made into yeast tablets, such as raw mother tablets, to treat indigestion caused by unreasonable diet. People with weak constitution can regulate metabolic function to some extent after taking it. In the process of yeast culture, if some special elements are added to make the yeast contain trace elements such as selenium and chromium, it will have certain curative effect on some diseases. If selenium-containing yeast is used to treat Keshan disease and Kaschin-Beck disease, it can prevent cell aging to some extent; Chromium-containing yeast can be used to treat diabetes.
Feed yeast is usually made from Candida or Kluyveromyces fragilis by culture and drying. It is a powdery or granular product, which has no fermenting power and dead cells. It is rich in protein (about 30 ~ 40%), B vitamins, amino acids and other substances, and is widely used as a protein supplement for animal feed. It can promote the growth and development of animals, shorten the feeding cycle, increase the amount of meat and eggs, improve meat quality and increase lean meat. & gt
Question 3: What does yeast do? This is a fungus, yellow and white. We often mix flour, make wine, make sauce and so on. Are all chemical changes caused by yeast. Also called yeast or yeast.
Question 4: What does instant dry yeast 1t mean? It is a granular dry yeast dehydrated from fresh yeast. Because of its convenient use and easy storage, it is the most widely used yeast for making bread and steamed bread.
After treatment, instant dry yeast contains emulsifier, which is easily soluble in water and will not agglomerate. Easy to use.
Ordinary dry yeast needs to be dissolved in water to break the particles.
There is no difference in fermentation capacity and dosage between them. The dosage of bread is 65438+ 0.5% of flour.
Question 5: The yeast used does not have the ability of fermentation and reproduction, but is dry yeast powder or granular product for human consumption. It can be obtained by recycling yeast mud from brewery, or it can be specially cultivated and dried according to the requirements of human nutrition. The United States, Japan and some European countries add about 5% edible yeast powder to common foods such as bread, cakes, biscuits and scones to improve the nutritional value of food. Yeast autolysate can be used as an additive for meat, jam, soup, cheese, bread, vegetables and condiments. It is used as a food nutrition enhancer in baby food and health food. The 5'- nucleotide prepared from yeast autolysis extract can be used as an additive in combination with monosodium glutamate to enhance the flavor of food. The concentrated invertase extracted from yeast is used as liquefier for chocolate with square eggs. Extracting lactase from yeast produced in whey can be used to increase sweetness in milk processing, prevent lactose crystallization in whey concentrated solution, and meet the needs of lactose intolerant consumers. Tea Yeast: In the frozen mountain area of Taiwan Province Province, when people make oolong tea, they will first kill the tea leaves and then ferment them at low temperature. After fermentation, the yeast will retire and settle at the bottom. But at this time, the yeast has already absorbed the essence of oolong tea, and after cleaning, disinfection and drying, it has become a tea yeast. There are three kinds of tea yeast in the market: the yield of tea yeast processed as above is low, and there is basically no yield, because it is difficult to collect after being separated from tea; Oolong tea and fermentation broth are dried together and crushed into powder, which is basically oolong tea and contains almost no yeast; Oolong tea extract is combined with beer yeast extract. The product is easy to collect and process, and can be produced on a large scale. Tea yeast has a wide range of uses, and the most popular one is suitable for slimming. Tea yeast containing tea polyphenols, its antioxidant capacity is more than E 10 times higher than that of vitamin e, which can reduce the content of neutral fat in blood and effectively reduce blood lipid. It can also improve the alkaloids of listlessness and lethargy caused by obesity and hyperlipidemia, and make you feel refreshed. Beer yeast-contains more abundant vitamin B, which is three times that of tea yeast, and yeast chromium is twice that of tea yeast. B vitamins can accelerate the metabolism of carbohydrate and fat, consume calories quickly, and make people energetic while losing weight; Yeast chromium reduces neutral fat and helps insulin accelerate sugar metabolism. The concept of real tea yeast should be like this: it contains effective ingredients such as oolong tea to lose weight and has the characteristics of yeast. Beer yeast is also a hot-selling product to lose weight, which shows that yeast itself is effective in losing weight, while tea yeast has the advantage of combining the characteristics of tea and yeast to lose weight, which is healthier, more effective and safer. Yeast used to brew beer. Most of them are different kinds of Saccharomyces cerevisiae. e？ c？ Hansen (1883) began to isolate and cultivate yeast and used it to brew beer. The following yeasts from Karl * * erg Brewery Institute in Denmark are famous. Other famous beer yeasts are German Saaz type bottom yeast and British and Japanese top yeast. The cell morphology is the same as other cultured yeasts, and it is a nearly spherical ellipsoid, which is different from wild yeast. Beer yeast is a typical upper fermentation yeast commonly used in beer production. Besides brewing beer, alcohol and other drinks, bread can also be fermented. The strain is rich in vitamins and protein, and can be used as edible, medicinal and feed yeast, and cytochrome C, nucleic acid, glutathione, blood clot, coenzyme A and adenosine triphosphate can also be extracted from it. In microbial determination of vitamins, biotin, pantothenic acid, thiamine, pyridoxine and inositol are usually determined by beer yeast. The colony of beer yeast on wort agar medium is milky white, shiny, flat and tidy. The asexual reproduction is mainly budding. It can ferment glucose, maltose, galactose and sucrose, but not lactose and melibiose. According to the length-width ratio of cells, beer yeast can be divided into three categories. The cells in the first group are mostly round, oval or oval (cell length and width 2). This yeast is resistant to high osmotic pressure and high salt concentration, and is suitable for producing alcohol from sugarcane molasses. Bread yeast can be divided into pressed yeast, active dry yeast and fast active dry yeast. Squeezing yeast: produced by Saccharomyces cerevisiae, with water content of 70 ~ 73 ... >; & gt
Question 6: What is a real "natural" yeast? In fact, many flavors in wine are produced by yeast fermentation, not from grapes. You may hear the winemaker say, "I only use natural yeast in my fermentation." What does this mean? How about wine with natural yeast? The meaning of "natural" yeast is misinterpreted, because all the yeasts we use in fermentation (including genetically modified organisms and uncommon ones) are natural. The correct statement should be "indigenous" yeast, which means that the yeast used for fermentation is produced from the fermentation environment, not artificially added. The artificially added yeast should be called "cultured yeast". They come from nature, are screened, cultivated and propagated, and then sold to winemakers for brewing. Most winemakers choose to use cultured yeasts because their fermentation is controllable. When using local yeast, brewers have to take great risks. They don't know what will happen, and many local winemakers are not very good at brewing and raw materials, so the taste of the wine will get worse. Why do some brewers take the risk? There are two main reasons. First of all, many winemakers believe that native yeast represents an important part of characteristic wine customs, vineyard characteristics or vineyard conditions. For me, this view does have some dogma, because bad wine always goes bad. Interestingly, most winemakers who choose to use local yeast for local reasons have vineyards and their favorite yeasts. Many winemakers have tried to ferment with native yeast, but some people choose to give up because the improper use of yeast leads to the deterioration of wine. Secondly, many experiments and facts have proved that the aroma and structure of wine brewed with various yeasts produced in nature are more complicated, so many people choose to use local yeasts. As you can imagine, the yeast industry has noticed this problem, and some winemakers have pointed out the differences, so the next time you hear the word "natural yeast", remember that it only represents a part. Brewing is not a job once and for all. What a brewer can use to make good wine, others may use it to make bad wine.
Question 7: What is yeast extract? By name,