What is yeast?
History of yeasts
●About 4000 years ago ancient Egyptians used yeast to make bread.
Archaeologists exploring Egyptian heritage sites found early grinding stones and baking chambers for making yeasted bread as well as drawings of 4000-year-old bakeries and breweries.
The left picture shows the bread made by ancient Egyptians. This Egyptian(right) was preparing beer barrel.
●As early as the Yin and Shang dynasties ancient Chinese used yeast to brew liquor. In the Han Dynasty Chinese began using yeast to make steamed bread cake and other pastries;
●In 1680 Dutchman Antonie van Leeuwenhoek observed yeast under a microscope for the first time.
●In the 19th century French scientist Pasteur discovered that yeast plays an important role in brewing alcohol.
●In 1846 the first industrialized production of yeast began in Europe.
●In the mid-1980s modernized production of yeast began in China.
●Angel is the first enterprise to embark upon modernized production of yeast in China and is presently one of the largest yeast producers in the world.
Origin of name of yeast
The word "yeast" comes from ancient Indo-European word gist or gyst meaning boil foam or bubble which vividly describes the function and effect of the matter yeast in brewing and fermentation.
The Chinese characters "酵母" first appeared in the Song Dynasty in a Chinese book on brewing which documented the method for collecting yeast microbe from the surface of the liquid in the brewing jar with full fermentation and the yeast microbe is called .Structure and nutritive
Composition of yeast cell
The yeast used in daily life is a single-cell microbe shaped like an egg. The size of yeast cell is only 5-8μm. Due to its tiniest minuteness a yeast cell is visible only through a microscope.
The outermost layer of yeast cell is the cell wall which plays a major role in protecting the cell and is mainly composed of glucan and mannan.
Through modern technology we can open the cell wall to reach the content of a yeast cell and obtain YE yeast extract through zymolysis. Yeast extract contains proteins peptides amino acids nucleic acids B vitamins and trace elements etc.
Two living modes of yeast
In the anaerobic environment the yeast breaks down the sugar and releases carbon dioxide in a process known as fermentation. In the process of leavening dough the yeast in the dough begins transforming the sugar in the flour into alcohol volatilized in baking and carbon dioxide after oxygen has been depleted so as to expand the dough.
Sugar--> CO2 + alcohol + a little energy
In the aerobic environment the yeast breaks down the sugar into carbon dioxide and water and obtains plenty of energy required by growth which accelerates the reproduction. This principle is utilized to produce yeast microbe in large quantities.
Sugar + O2--> CO2 + water + high energy
Mode of yeast reproduction
Yeast has two modes of reproduction including asexual reproduction and sexual reproduction and the commonest growth mode of yeast is the asexual reproduction through budding or fission.
A small bud or daughter cell will be formed on the mother cell in this reproduction. The nucleolus of mother cell becomes a daughter cell through fission and enters the daughter cell and the bud keeps growing until it is separated from the mother cell and forms a new cell.
Yeast is the only microbe whose annual production worldwide exceeds 1 million tons
Yeast is the only microbe whose annual production worldwide exceeds 1 million tons and is widely used in brewing food medicine feed cosmetics and other industries. The yeast industry has become an independent industrial system in the world with an estimated annual production of more than 1.2 million tons on a dry basis.
As an important innovation in the development of the yeast industry YE yeast extract has been surging ahead since the 1990s. Worldwide production is estimated at more than 100000 tons per annum on a dry basis and the prospects for YE application are brilliant.
Commercial Yeast production process
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Forms of commercial yeast
Intended for large industrialized bread makers and transported by tank truck;
Highly viable and economical;
Can be stored for 10-14 days at refrigerating temperatures of 2-4℃
Cubic yeast products containing about 70% water;
Powerful dough leavening capacity;
Can be stored for about 1 month at temperatures of 0-4℃
Typically vacuum packaged or packaged in aluminum foil bags filled with inert gas;
Shelf life - 1-2 years;
Easy to store transport and use.
Compared to the fresh yeast, it has longer shelf life, with storage conditions at -18 degrees, it can be preserved for 2 years
Active Dry Yeast
form of granules or spherical particles. It offers excellent stability at ambient temperature, a characteristic which makes it very popular in those parts of the world where climatic conditions are less than favourable (i.e. high temperatures and humidity levels).
Yeast is a great contribution to humanity
1. Yeasts with different capabilities form a yeast group army to serving human beings in all fields.
Various yeasts are selected from the nature and are endowed with relevant capacity in specific environment in the method of targeted slaving.
Therefore more and more yeasts with different capabilities form a yeast group army and people can easily select their desired yeast corps from the yeast group army and apply them to various purposes.
For example in the yeast group army there is the yeast with powerful aerogenesis capacity the yeast with powerful alcohol generation capacity at regular temperatures the yeast with powerful alcohol generation capacity at high temperature;
2. Yeast is a bio-factory which contributes many ideal products to human
Someone people calls yeast a bio-factory while others calls yeast a bio-converter for people utilize yeast to develop many efficient bio-products.
People use yeast factory to ferment and culture and transform the inorganic
minerals, such as zinc selenium chromium, into organic selenium yeast, chromium yeast and zinc yeast, to provide human with ideal source of minerals with high bioavailability.
Yeast contains high levels of various nutrients. In the yeast factory people can enrich the yeast as they need and make the yeast rich in B vitamins or nucleic acid so that people can develop health product with high content of B vitamins or nucleic acid;
Yeast is also the good expression carrier of genetic engineering. People utilize the simple life structure stable information expression good fission reproduction of yeast to produce many genetic engineering products in the yeast factory such as various biological vaccine organic acids etc.
Yeast is a globally recognized safe food
Yeast is the best food and the most natural antidote.
--American M.D nutritionist: Henry G.Bieler
Yeast powder can improve the condition of most people in the world caused by nutritional imbalance
--American nutritionist: Adelle Davis
Yeast is almost the only natural food integrating rich high-quality protein and a complete range of B vitamins in the current nature.
--Japanese famous nutritionist: Akazawa
Application fields of yeast
I. Food industry
1. Food fermentation
The bread and steamed bread made of yeast are more nutritional healthy and hygienic.
Yeast transforms the carbohydrate decomposed by starch in the flour into carbon dioxide and other chemical elements and makes the dough fluffy under the effect of the gas. Yeast fermentation natural nutritional convenient and fast fundamentally resolves the shortcomings of traditional fermentation method such as sour dough fermentation, low fermentation unhygienic and easy to turn sour.
The alcohol produced by breakdown of sugar gives the dough a special flavor and enhances the taste of bread and steamed bread.
In the fermentation process yeast can also break down the phytic acid in the flour that inhibits human body to absorb minerals and allow people to easily obtain mineral nutrition as calcium iron zinc etc.
Various yeast fermented food
Chinese traditional pastries
Deep-fried dough sticks
Fermented rice product
2. YE applied in flavor field
Scientific research has found that the pleasant taste that people can feel mainly comes from three substances: glutamate inosinic acid and guanylic acid.
Kelp is rich in glutamic acid champignon is rich in guanylate and carp is rich in inosinic acid. The combination of the three substances will form the most enjoyable taste.
Taking the natural edible yeast as the raw material YE yeast extract adopts modern bio-technology to decompose the protein nucleic acid etc. in the cell into nutritional flavoring which is rich in a variety of nutrients as glutamic acid inosinic acid and guanylic acid as the international popular new top-grade flavoring. In the developed countries and regions YE has replaced traditional flavoring and been widely applied in food and flavor as an important iconic ingredient with clean label.
3. Beverage and alcohol field
The reason why yeast can transform sugar into alcohol is that the yeast cell contains some proteins known as enzymes. These enzymes are good biological catalysts which break down the organic matter as glucose and other carbohydrates provide the energy required by their activity reproduction and the metabolite forms alcohol as a result of biochemical reaction.
Application instance of yeast brewing:
Wine and fruit wine
II. Human health
Yeast is an ideal nutrition source for human beings and its nutritional characteristics can be summed up as three lows and four highs; that is low fat low sugar and low calorie and high-quality protein high-quality complete B vitamins high-quality minerals and high-quality dietary fiber. Yeast is an ideal health food without cholesterol that conforms to the modern human dietary structure.
In the fermentation process yeast can transform inorganic trace elements into safe organic trace elements with high bioavailability such as yeast selenium yeast zinc yeast chromium etc.
The polysaccharide material such as beta-glucan in yeast cell wall is a highly active immune substance and an ideal immunopotentiator. Yeast is also a source for health actives such as nucleic acids, glutathione, peptides etc.
Yeast can also be used as probiotics. Discovered in the 1920s and after nearly a century of research, Saccharomyces Boulardii has been found to have a significant effect on anti-diarrhea caused by various factors. Certain strains of Saccharomyces cerevisiae can also maintain the balance of intestinal flora.
All of those nutrition characters make yeast an ideal ingredient which can be widely applied in health foods, dietary supplements and medicines.
III. Industrial fermentation
New bio-energy: Fuel Ethanol
With the current energy shortages around the world the production of fuel ethanol through yeast fermentation has become an inevitable trend.
In the alcohol thick mash fermentation the yeast can transform the sugar in cassava cereal crops into fuel ethanol with the thickness of 96%. At present the technology using timber waste paper straw and other cellulose as raw material and utilizing yeast fermentation to produce new energy has achieved great progress; this invention can effectively obtain ethanol from cheaper raw materials and this new energy will gradually replace gasoline fuel due to its unparalleled advantages.
As a high-quality organic nitrogen source of culture medium yeast extract YE is a powder paste or liquid product rich in protein amino acids small peptides nucleotide B vitamins trace elements and other nutrients produced by bread yeast beer yeast or wine yeast in the process of autolysis or enzymatic hydrolysis through a separation and concentration or spray-drying process.
At present as an important culture medium source yeast extract is widely applied in the laboratories and factories.
Yeast extract is essential to the production of long-chain dibasic acid. As the important fine chemical intermediate long-chain dibasic acid can synthesize a series of high value added special chemicals as spices special nylon polyamide hot melt adhesive etc. the production of long-chain dibasic acid is completed through the yeast catalysis.
Chiral drug synthesis
The oxidoreductase in the yeast cells is a chiral synthesized catalyst which can catalyze and reduce the substrate with carbonyl and synthesize chiral products with optical activity. According to this principle yeast has been widely used in the catalysis and synthesis of chiral drugs as Tomoxetine/Fluoxetine β-lactam antibiotics L- Carnitin paclitaxel fenfluramine aminoglutethimide etc.
IV. Animal nutrition and health
Yeast has become one of the most extensively used microbiological feeds in the global breeding industry.
The yeast-based biological feed is highly effective in regulating animal gastrointestinal environmental balance improving the body immunity promoting feed digestion and absorption improving the production performance of animal improving animal product quality and reducing pollutant discharge.
Feed-purpose high-activity dry yeast
V. Petrochemical industry
Yeast can selectively utilize paraffin in the oil as carbon source so as to reduce the paraffin content in the oil product reduce the solidifying point improve the oil fluidity at low temperatures; as such it has successfully applied in the production of oil with low a solidifying point. Yeast can also be used to decompose pollutants the ocean rivers lakes and bodies of water. .