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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, and is 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 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, combined with monosodium glutamate to enhance food flavor (see nucleotide condiment). 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

What is yeast for?

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.

What is yeast?

Yeast is some unicellular fungi, not a unit of phylogenetic classification. Yeast is the earliest microorganism used in the history of human civilization. Can survive in an anoxic environment. At present, there are more than 1000 kinds of yeast. According to the ability to produce spores (ascospores and basidiospores), yeast can be divided into three types: the strains that form spores belong to ascomycetes and basidiomycetes. Those fungi that do not form spores but propagate mainly through budding are called incomplete fungi, or "false yeast" (similar to yeast). At present, it is known that most yeasts are classified as Ascomycetes. Yeast is widely distributed in nature, mainly growing in acidic, humid and sugary environments, and is also very important in wine brewing. And the cat will swell up after eating, which is very dangerous.

What is dry yeast? How to use it?

A. Dry yeast is a domestic starter for fermented dough such as traditional flour fertilizer, which has high fermentation stability, is not easy to produce mixed bacteria and has no sour taste.

Easy to use, very convenient to use directly in flour. Buy a bag and try it yourself. There are instructions on the package.

What is semi-dry yeast? What is the difference between dry yeast and fresh yeast?

Masters and bosses in pastry and baking industries all know that the correct use of yeast is the key to making steamed bread or bread with good flavor, easy use and simplicity.

Now many users know that yeast is a food, not a food additive, so you can use it with confidence. But there are many kinds of yeasts, and the products made by different yeasts have different flavors. For example, using high-activity dry yeast, the dough is stable but the flavor is slightly worse; The fresh yeast has a good flavor, but the cold storage conditions are too harsh for users to use. Is there a compromise that can keep good flavor and be easy to preserve?

The answer is yes. Angel Yeast Co., Ltd., a leading domestic yeast enterprise, recently launched this product-semi-dry yeast.

The so-called "semi-dry yeast" has the advantages of good fermentation flavor and strong fermentation ability, and is suitable for making frozen dough; At the same time, it also has the advantages of good fluidity of dry yeast and suitable for weighing and long-term storage. Semi-dry yeast has unique characteristics.

It is reported that semi-dry yeast is the first in China, representing not only a new product, but also the embodiment of Angel's pursuit of maximizing customer value.

Mr. Lu Fa, R&D engineer of Angel Yeast, said that semi-dry yeast has the following advantages:

1, which can realize long-distance transportation and facilitate customers' demand for yeast flavor. Dry yeast will inevitably produce dead yeast during the drying process, which will not only break gluten, but also produce odor, so many professional bakers prefer fresh yeast when choosing yeast. However, due to the influence of transportation, storage, climate, transportation distance and other factors, it is difficult to buy fresh yeast in some southern and remote places, while semi-dry yeast can be transported to places far away from factories because of its shelf life of one year, which is convenient for customers to buy and use.

2. Long-term storage conditions are below-18 degrees Celsius, and no special storage facilities are needed. Fresh yeast is usually stored in cold storage at 0-4 degrees Celsius. In this case, the yeast has metabolism, and then the fermentation activity will decrease. So the shelf life of fresh yeast in this environment is 45 days, and the shelf life is short. However, when stored under frozen conditions, fresh yeast cells are easily damaged because of their high water content, which seriously reduces yeast activity. Many users in the market do not have special freezers, which makes users have great limitations in preservation. Semi-dry yeast can be stored at-18℃, and can be put together with other frozen products such as whipped cream for user's convenience. Compared with fresh yeast, the shelf life of semi-dry yeast can be as long as one year.

3. Semi-dry yeast is also beneficial to the distribution of middlemen. During the short-distance transportation of fresh yeast from middlemen to users, it is also required to be in a cold storage state, and the temperature will rise rapidly if you are not careful, which makes the quality of fresh yeast not guaranteed. The temperature range of semi-dry yeast is-18 degrees Celsius to 4 degrees Celsius. Even if middlemen use ordinary logistics for short-term transportation, it will not have a great impact on yeast quality, which is convenient for middlemen to distribute and the distribution radius can be appropriately increased.

4. Semi-dry yeast can help users reduce the use cost. Semi-dry yeast has a high number of living cells, and dry yeast contains about 15% dead yeast, so its fermentation activity is stronger. Compared with fresh yeast, the dosage of semi-dry yeast is only 0.4 times that of fresh yeast, which can help users reduce costs.

5. Semi-dry yeast is suitable for making frozen dough. There are many dead yeasts in dry yeast, and the gluten is damaged greatly; However, fresh yeast is not suitable for frozen storage, so it is not suitable for frozen dough making. The self-preservation condition of semi-dry yeast is-18℃, which is very suitable for making frozen dough and can effectively improve the shelf life of frozen dough.

Therefore, semi-dry yeast is a great innovation for customers in transportation, storage conditions and use effect, which can bring value to customers. Will be a dark horse in the future yeast market!

What is Angie's yeast made of?

It is made of yeast and emulsifier.

Yeast is divided into fresh yeast and dry yeast. It is an edible and nutrient-rich single-celled microorganism, which is called "inexhaustible nutrient source" in nutrition. Besides protein, carbohydrates and lipids, yeast is also rich in vitamins, minerals and enzymes.

Method for prepare fermented dough by yeast:

The first step is to put a proper amount of noodles in the basin.

Step 2: Take the yeast according to the ratio of flour to yeast of 200: 1, put the yeast into a small bowl and stir it evenly with warm water. The water temperature is similar to the body temperature.

Step 3, dig a hole in the middle of the noodles and pour in yeast water. Mix the yeast water and flour with chopsticks.

Step 4, prepare warm water, then pour it into the dug hole and stir the noodles with chopsticks to make them flocculent.

Step five, knead the flocculent noodles together by hand, and then knead the noodles hard after feeling soft. Knead into a ball.

Step 6, cover the surface with a layer of gauze and put it in a warm place for about an hour. You can open the middle to see if there is a honeycomb in the middle of the flour. If it is, it means that the flour is fermented.

What kind of additive does yeast belong to?

Saccharomyces cerevisiae, also known as Saccharomyces cerevisiae or budding yeast. Baker's yeast is a kind of yeast with the most extensive relationship with human beings, not only because it is traditionally used for making bread, steamed bread and other foods and brewing wine, but also as a eukaryotic model organism in modern molecular and cell biology, and its role is equivalent to that of prokaryotic model organism Escherichia coli. Baker's yeast is the most commonly used biological species in fermentation. The baker's yeast cells are spherical or oval, with a diameter of 5–10 μ m. The propagation method is bud grafting.

Saccharomyces cerevisiae is the first eukaryotic organism to complete genome sequencing, which was completed in 1996.

The genome of Saccharomyces cerevisiae contains about120,000 base pairs, which are divided into 16 groups of chromosomes. * * * has 6275 genes, of which about 5800 may have real functions. It is estimated that about 23% of its genes are homologous to humans. Saccharomyces genome database contains detailed annotations of yeast genome, which is an important tool for studying eukaryotic cytogenetics and physiology. Another important Saccharomyces cerevisiae database is maintained by the protein Sequence Information Center in Munich.

Before the sequencing project of Saccharomyces cerevisiae began, about 2600 genes encoding RNA or protein were identified by traditional genetic methods. By sequencing the whole genome of Saccharomyces cerevisiae, it was found that there were 5885 open reading frames encoding specific proteins in the whole genome sequence of 12068kb. This means that there is a gene encoding protein in the yeast genome every 2kb on average, that is, 72% of the nucleotide sequence of the whole genome consists of an open reading frame. This shows that the arrangement of yeast genes is closer than other higher eukaryotes. For example, in the genome of nematodes, there is a gene encoding protein every 6kb on average; In the human genome, it takes an average of 30kb or more to find a gene encoding protein. The compactness of yeast genome is due to the short interval between genes and the scarcity of introns in genes. The average length of the open reading frame of yeast genome is 1450bp, which is 483 codons. The longest open reading frame is located on chromosome XII with unknown function (codon 49 10), and a few open reading frames exceed codon 1500. In the yeast genome, there are also genes encoding short proteins, for example, PMP 1 gene encodes a plasma membrane protein lipid composed of 40 amino acids. In addition, the yeast genome also contains: about 140 genes encoding RNA, arranged at the long end of chromosome XII; 40 genes encoding SnRNA, scattered on 16 chromosomes; 275 tRNA genes belonging to 43 families are also widely distributed in the genome.

Sequencing revealed a wide range of base composition changes in the yeast genome. Most yeast chromosomes are composed of GC-rich DNA sequences and GC-deficient DNA sequences in varying degrees and in a wide range. This change of GC content is related to chromosome structure, gene density and recombination frequency. The regions with high GC content are generally located in the middle of chromosome arm, and the gene density in these regions is high; The regions with low GC content are generally close to telomeres and centromeres, and the number of genes in these regions is relatively small. Simchen et al. confirmed that the relative incidence of yeast genetic recombination, that is, double strand breaks, is coupled with GC-rich regions of chromosomes, and the recombination frequency of different chromosomes is different. The recombination frequency of smaller chromosomes ⅰ, ⅲ, ⅳ and ⅸ is higher than the average recombination frequency of the whole genome. ?

Another obvious feature of yeast genome is that it contains many repetitive DNA sequences, some of which are identical DNA sequences, such as rDNA and CUP 1 gene, Ty factor and its derived single LTR sequence. There are a large number of trinucleotide repeats in the open reading frame or gene spacer, which has aroused great concern. Because some human genetic diseases are caused by changes in trinucleotide repeats. There are many highly homologous DNA sequences, which are called genetic redundancy. Many chromosomes in yeast have highly homologous regions with a length of more than tens of kb at the ends, which are the main regions of genetic abundance, and these regions are still undergoing frequent DNA recombination. Another form of genetic abundance is single gene duplication, in which the dispersed type is the most typical, and the other rare type is cluster distribution gene family. Cluster homology region (cluster homology >:>

What is instant dry yeast?

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 are obviously some differences in cost, but the huge sales of instant dry yeast make the cost no longer different.

There is no difference in fermentation capacity and dosage between them. The dosage of bread is 65438+ 0.5% of flour.

What is the common name of yeast powder?

Commonly known as "baking soda" and "baking soda powder"

What is yeast powder and where can I buy it?

Yeast powder is used for fermentation. It is said that you can also add something to it to make a mask ~ ~ ~ You can buy it in general supermarkets, and the package clearly says yeast ~ ~ ~

PS yeast powder is different from the dry yeast sold in ordinary small supermarkets. Never take it seriously. Dry yeast is used to make steamed bread and dried bread slices ~ ~ ~ If the yeast powder you want is used to make facial mask or nutrition, you can go to pharmacies, supermarkets and health food stores such as Wal-Mart, Lotus, Carrefour, and of course it is also sold online.