2.1 Main raw materials

2.2 Supporting materials

5.3 Isolation of yeast

5.5 Yeast storage

5.6 Drying yeast

6. APPENDIX

1. TECHNOLOGICAL SCHEME OF YEAST PRODUCTION

1.1 Schematic diagram of production

The technological scheme for the production of baker's yeast at molasses and yeast plants is presented in the Appendix.

The technological process of growing yeast consists of separate main stages: preparation of a nutrient medium, growing yeast, isolation, molding and packaging of compressed yeast, drying and packaging of dried products.

Preparation of the culture medium.

A nutrient medium is understood as solutions of molasses, as well as solutions of nitrogen- and phosphorus-containing salts. Thick molasses from molasses storage is transferred to collection 1, where its daily supply is stored. From the collector 1, the molasses is sent to the scales 2, from where, after weighing, it is transferred to the collector for diluting the molasses 3, where it is diluted with water. This process is called dilution. Then the molasses solution is fed to clarifiers 4, where it is freed from mechanical impurities - this process is called clarification. The clarified molasses is pumped into the supply collectors for molasses 7, from where it is fed to the yeast-growing apparatus.

Nitrogen- and phosphorus-containing salts are dissolved separately in special containers with water and used to feed yeast in the form of solutions, which are fed into yeast-growing apparatus from supply collectors for salts 5, 6. Separate tanks are used for each salt both for dissolving it and for inflow.

Growing yeast.

This stage is the main one in the production of baker's yeast. Cultivation of yeast is the process of multiplication of yeast cells, when from a small number of cells seeded into the nutrient medium, gradually, by a series of successive stages, a large amount of yeast is obtained, which is used in a number of industries, and primarily in baking.

The process of growing yeast consists of two stages: obtaining uterine and commercial yeast. The mother yeast is first obtained in the laboratory of the plant, and then in the shop of pure cultures, for which yeast-growing apparatus 8 and 9 are used. First of all, pure culture yeast (CK) is obtained, and from them - naturally-pure culture yeast (NEC). A pure culture is called a yeast grown from one cell, without admixture of foreign microorganisms. The first stages of CK yeast propagation take place in the laboratory of the plant, then in the workshop for pure cultures and, finally, in a production yeast-growing apparatus designed to breed a pure and naturally pure culture. A naturally pure culture is a yeast that contains a small amount of foreign microorganisms and is used as a seed for growing commercial yeast.

Commercial yeast at domestic yeast factories is obtained in two stages: stage B - seed yeast, which is grown in apparatus 10 and stage C - commercial yeast, which is grown in apparatus 11 with maturation in apparatus 12.

Isolation of yeast.

The grown uterine and commercial yeast is isolated from the culture medium (the medium in which they multiplied), washed with cold water and concentrated to a concentration of 500-600 g / l on special machines - separators 13, 15. For washing the yeast use special tanks 14. Condensed yeast is called yeast milk. After separation, they are sent to special collectors of yeast milk. Yeast milk of uterine yeast is placed in collectors 23, and commercial yeast - in collectors 24. During separation, up to 80% of the liquid is separated.

The final separation of the yeast from the liquid takes place on special machines called vacuum filters or filter presses (16), which are fed with yeast milk from collectors. In this case, the yeast acquires a dense consistency and the form of plates or layers of various thicknesses.

Yeast forming and packaging.

Yeast plates from vacuum filters or filter presses are fed by a conveyor into the bunker 17 of the forming and packaging machine 18, where they are molded into bars of various weights and packed into special label paper.

Drying and packaging of dried products.

In some yeast factories, compressed yeast, bypassing forming, is sent to drying units (dryers), where they are shaped into vermicelli, crushed and then dried. Dried yeast is in the form of granules.

Dried yeast is packed by hand in kraft bags with a polyethylene liner, or in boxes with parchment paper, or packaged on special machines in hermetic packaging - cans.

1.2 Cultivation methods and process indicators

When growing yeast, methods are used that differ in the mode of supply of nutrients, air and the duration of the process. At the same time, there are no-intake, air-supply air-flow methods.

The non-flow cultivation method is used to obtain uterine yeast. According to this method, all nutrients are supplied to the water immediately when the apparatus is loaded. In this case, air is either not supplied at all, or supplied periodically, or a small amount throughout the entire cultivation period.

Air-inflow is the method in which the yeast is grown with a constant supply of air and a gradual inflow of the nutrient medium into the yeast-growing apparatus. This mode is called periodic. It is usually used in the production of the last stages of uterine yeast, as well as commercial yeast.

Air-flow is a method in which the yeast is grown with a constant supply of air and a simultaneous inflow of the nutrient medium into the yeast growing apparatus and the outflow of the culture medium with yeast into the selection. At the same time, within 6-7 hours the yeast accumulates in the yeast-growing apparatus - this period is called cumulative. After 6-7 hours, the outflow of the medium with yeast from the yeast-growing apparatus begins into the selection apparatus - the outflow period, or the selection period, which lasts 20-30 hours or more - an extended or continuous mode.

The accumulation period takes place mainly in the yeast-growing apparatus, where the nutrient medium and air are continuously supplied. In this case, yeast cells, as in the periodic method, go through a lag phase and a phase of logarithmic growth, which lasts continuously. In the first hours, there is synchronous budding of daughter cells with a low coefficient of hourly growth (1.08-1.10), then the increase increases and by the 5th and 6th hours the coefficient of hourly growth reaches the value of 1.20-1, 25. the maximum possible amount of yeast accumulates in the culture medium, the so-called "working biomass", after which a period of continuous propagation, or selection period, begins.

During this period, in the main yeast-growing apparatus, cells are in the stage of logarithmic growth and a constant ratio of cells in size and enzymatic activity is established. The number of large cells is 20%, average 55% and small no more than 25-30%. The qualifying period can last indefinitely if the following conditions are met:

Providing yeast cells with the necessary nutrients and growth substances, as well as oxygen in sufficient quantities;

Continuous withdrawal from the yeast-growing apparatus of metabolic products (metabolism) of cells, inhibiting their growth and reproduction;

Continuous selection of incremental biomass from the main yeast-growing apparatus.

The stationary phase of yeast development in a continuous process begins only in the selection apparatus, where nutrients are not supplied and from where the growing biomass is continuously taken.

Thus, the yeast grown in the main apparatus is characterized by the activity of enzyme systems, i.e. the ability to actively grow and reproduce at a constant rate set for this apparatus and the processed raw material. From the correct conduct of this process in the selection apparatus, mainly the quality of the yeast will whistle.

1.3 Main calculated indicators

Yeast yield

The main indicator of material cost efficiency and the yeast industry is yeast yield. The yeast yield is understood as the amount of yeast referred to processed molasses and expressed as a percentage. The yeast yield B is calculated by the formula:

where D is the amount of yeast obtained, kg; M - the amount of consumed molasses, kg.

The yeast yield in different plants is different and depends on the design of the equipment, the technological scheme, the quality of raw materials and materials, the supply of electricity, water, steam, etc.

Calculation of the consumption of molasses per 1 ton of yeast

At yeast factories, when calculating the consumption of molasses with a content of 46% sugar, the output and production of yeast, which are planned by a higher organization, depending on the technical condition of the enterprise and its capacity, are taken as a basis.

The consumption of molasses M for the plant, as well as for each stage, is calculated by the formula

where D is the amount of yeast, kg; B - yeast yield,%.

2. RAW AND AUXILIARY MATERIALS

2.1 Main raw materials

The main source of yeast nutrients is beet molasses, which is a thick, syrupy liquid.

Characteristics of molasses

The molasses contains sugars (carbohydrates), non-sugar and water. The main part of molasses carbohydrates is sucrose С12Н22О11, the amount of which ranges from 40-50% in some cases, 54-56%. In addition to sucrose, molasses contains invert sugar and raffinose. Invert sugar (a mixture of glucose С6Н12О6 and fructose С6Н12О6) of molasses comes in part from beets, where it is contained in an amount of 0.1-0.2%. The invert sugar content increases significantly in rotten and frozen beets. A significant part of invert sugar is formed as a result of the hydrolytic breakdown of sugar during sugar refining.

The inversion products - glucose and fructose - reduce the sucrose content and deteriorate the quality of molasses, since in the process of sugar refining they turn into acids and dyes. Raffinose is found in beets in the amount of 0.01-0.03%. It is resistant to high temperatures and the action of alkalis in the production of sugar, therefore it completely transforms into molasses and its content sometimes reaches 2%. Raffinose C18H32O16 is a trisaccharide consisting of galactose, fructose and glucose.

In yeast production, the carbohydrate content in molasses is taken into account by the sum of fermentable sugars, which is the total amount of sucrose, invert sugar and 1/3 of raffinose.

Non-sugar molasses are composed of organic and inorganic substances. Inorganic substances contain carbonate, sulfuric acid, chloride, nitric acid and in small amounts phosphate salts of potassium, sodium, calcium, magnesium, iron, ammonium.

The total amount of inorganic substances is determined by the composition of ash, which fluctuates depending on the soil and climatic conditions of growing beets.

When growing baker's yeast, not only the absolute ash content, but also the ratio of ash substances and sugars is of great importance for the accumulation of biomass. So, in full-fledged molasses, for every 100 g of carbohydrates, at least 15 g of ash, or 8-10% in relation to molasses, should fall.

The composition of organic non-sugar molasses includes nitrogen-containing and nitrogen-free compounds. Nitrogen-containing substances consist of the breakdown products of proteins - amino acids, amides and ammonium nitrogen, which are assimilated by yeast. Most of the nitrogen is betaine nitrogen, which is not assimilated by yeast.

Nitrogen-free substances consist of organic acids of oxalic, succinic, glutaric, etc.), volatile organic acids (acetic, formic, butyric, propionic), as well as caramels - the condensation products of carbohydrates formed under the influence of high temperatures in the process of obtaining sugar.

Water in molasses is contained in a free and bound state in an amount of about 20%. In addition, the molasses contains growth substances - biotin, pantothenic acid, inositol, aneurin, riboflavin, pyridoxine, nicotinic and folic acids, and trace elements: cobalt (Co), boron (B), iron (Fe), honey (Cu) manganese ( Mn), molybdenum (Mo). zinc (Zn).

The reaction (pH) of molasses and the presence of harmful impurities in it play an important role in the development of yeast. A complete molasses is considered to be neutral, slightly alkaline (pH 7.1-8.5) and slightly acidic (pH 6.3-6.9) molasses. Sour molasses (pH below 6.5) is not suitable for long-term storage. The presence of a large amount of dyes in molasses inhibits the growth of yeast and degrades its quality.

The content in molasses of such harmful impurities as sulfurous anhydride and volatile acids is not as important today as it used to be, since in recent years molasses with an increased content of sulfurous anhydride have practically not been found at all, and most of the volatile acids are found in molasses in bound state in the form of salts, much less harmful to yeast.

Molasses supplied to yeast factories can be divided into three main groups:

Molasses is normal, corresponding to the established rate;

Inadequate molasses containing insufficient amounts of substances necessary for normal yeast growth;

Defective molasses, content of harmful impurities that inhibit the growth of yeast (volatile acids, sulfurous anhydride, active nitrite-forming bacteria), molasses with increased color.

Normal molasses is processed in yeast production according to the accepted technological regimes without normalizing the composition, that is, basically without adding growth activators and potassium nutrition.

Influence of molasses composition on accumulation

biomass and yeast quality

When growing yeast on molasses, it is important to know the amount of nitrogen in it, assimilated by growing cells, the amount of growth and ash substances.

Nitrogenous substances. Molasses containing an insufficient amount of nitrogenous substances is an inferior raw material for the production of yeast. The criterion for assessing the suitability of molasses for production is the content of easily assimilable amino acids nitrogen. The molasses contains 17 amino acids, while aspartic and glutamic ones predominate, which accelerate the growth of yeast.

Growth substances (biotin). For the normal development of yeast, the presence of substances in the environment that stimulate the accumulation of biomass (biotin, inositol and pantothenic acid) is required. All these growth substances are contained in beet molasses in the following quantities (μg / kg): inositol 5,770,000-8,000,000, pantothenic acid 50,000-110,000, biotin 40-140. In this case, the amount of inositol and pantothenic acid usually corresponds to or slightly exceeds the amount that is necessary for the rapid accumulation of biomass with a high yield of finished products per raw material unit. The content of biotin, even in good quality molasses, usually does not reach the required norm (200-250 μg / kg). Therefore, when evaluating the suitability of beet molasses, the biotin content is a very important indicator.

The biotin content in molasses supplied to yeast factories varies widely - from 40-140 μg / kg and averages 83 μg / kg, and batches of molasses with a higher biotin content (115-140 μg / kg) are rare. Thus, in terms of biotin content, beet molasses does not meet the requirements of modern yeast production.

Yeast grown in biotin-deficient media has a weak enzyme system and therefore slows down its growth. Biotin-rich yeast is prepared for rapid multiplication, since biotin facilitates the assimilation of inorganic nitrogen from the environment by them and thereby promotes the formation of protein substances in the yeast cell. Such yeast contains ready-made enzyme systems, the active group of which is biotin.

Ash substances (potassium). The normalization of the molasses composition as a result of the addition of various biotin sources causes a significant acceleration of yeast growth. However, when processing some batches of molasses, a decrease in the stability of the finished product is observed, which is due to the insufficient potassium content in the molasses. In this case, nutrition is disturbed - ash elements do not enter the yeast cell during the growth process. Meanwhile, the composition of the ash of the yeast cell contains 23-40% potassium.

Potassium can be found in molasses not only in a free state, but also in a bound state, so it does not all participate in metabolic reactions when growing yeast.

The presence of potassium ions in the molasses medium is required for the manifestation of the activity of many enzymes that are involved in redox reactions and are actively involved in the growth and reproduction of yeast.

It is known from the practice of yeast factories that on molasses with a low potassium content, the growth and multiplication of yeast cells deviates from the norm: cell neoplasms slow down, yeast cells with two or three buds appear. This decreases yeast production and ultimately decreases yeast yield.

2.2 Supporting materials

For active yeast growth, it is necessary to add nitrogen, phosphorus, potassium, magnesium, growth substances, as well as drinking water and air to the culture medium.

Sulfuric acid H2SO4 is used to reinforce molasses solution during clarification, to adjust the pH of the culture medium during yeast cultivation, and to purify seed yeast from bacterial infection. In yeast production, sulfuric acid is used, technical contact improved (GOST 2184-67) and battery (GOST 667-73) with a monohydrate content of 92.5-94.0%, arsenic not more than 0.0001%.

Antifoaming agents are used to extinguish foam that forms during the growth of yeast in yeast-growing apparatus. In yeast production, technical oleic acid of grades A and B (GOST 7580-55) is usually used to quench foam, which contains at least 95% fatty acids in the anhydrous product, no more than 0.5% moisture and has a pour point of no more than 10 -16 ° C.

Disinfectants: bleach, technical sodium hydroxide, soda ash, formalin, lactic acid, boric acid, hydrogen peroxide, furacilin, sulfanol, etc.

Boric acid H3BO3 in the form of colorless shiny crystals or white crystalline powder, completely soluble in water, contains at least 99.0-99.8% boric acid (GOST 9656-75). It is used together with lactic acid to treat seed yeast and to suppress the microflora of molasses solution, since a mixture of these acids has a greater antibacterial activity than when using each acid separately.

Hydrogen peroxide (aqueous solution of H2O,) is a colorless transparent liquid with a content of 27.5-40% hydrogen peroxide (GOST 177-71). Possesses antibacterial activity and is used to inhibit the growth of bacteria in seed yeast.

Air. In yeast production, a large amount of air is used to aerate the fermenting liquid, which can contain a significant number of microorganisms (up to several thousand per 1 m3). In this regard, air intake must be carried out above the ridge of the plant's roof. The air must be filtered and cooled. Insufficient purification of the air supplied to the production can cause an increase in the number of bacteria in the culture liquid.

The air in production facilities, usually contaminated with bacteria and yeast cells, causes microorganisms to enter production environments and finished products.

3. PREPARATION OF THE NUTRITIONAL MEDIUM

3.1 Preparation of molasses solution

The process of preparing a molasses solution consists of diluting and clarifying it. Clarify molasses in order to remove coarse suspended particles, colloids, microorganisms and other impurities.

There are several ways to clarify molasses in yeast production. The choice of one method or another is usually determined by the structure of the preparatory department.

Mechanical method. Currently, in most yeast plants, molasses are clarified using clarifiers, where suspended particles are separated by centrifugal force. The specified method of clarification saves molasses, auxiliary materials, steam, in addition, the time for clarification is reduced.

Before starting on the clarifier, the molasses is weighed and diluted with water to a certain concentration (dilution ratio is 1-3), bleach is added at the rate of 2-3 kg (with 33% active chlorine content) per 1 ton of it. After mixing the solution with bleach, give a half-hour "chlorine exposure", then add sulfuric acid to obtain a pH of 4.5 - 5.0 and send it to the clarifier.

Some factories use molasses sterilization. At the same time, it is diluted with hot water at a temperature of 80-90 ° C and sent to the sterilizer. Sterilization is carried out at a temperature of 105-125 ° C for 15-60 s, after which the molasses solution is cooled to 80-85 ° C and fed to the clarifier.

Sludge acid-cold method. This method is used in yeast production of small capacities (5-10 tons / day) and in the absence of clarifiers. Water and molasses are collected in the mash tun (about 0.75 m3 of water per ton of molasses). After stirring, bleach is poured into the apparatus at the rate of 0.6-0.9 kg of active chlorine, then stirred for another 30 minutes and the mash is left at rest for 30 minutes. During this time, microbes - pests of yeast production - become inactive under the influence of chlorine and gradually die.

After exposure, a stirrer is turned on, sulfuric acid is added until a pH of 5.0 is obtained, stirred for 30 minutes and water is added until the solids content in the molasses is 20-40% (depending on the concentration adopted at the plant) and the mash is allowed to settle for 10-12 hours (until the molasses turns transparent).

The dosage of molasses solution is carried out according to the program using automatic devices or manually.

When clarifying molasses by the acid-cold settling method, the loss of molasses is 1.8-1.4% of the original volume.

To reduce the loss of molasses during clarification in yeast production, we mainly switched from the settling method to mechanical (using clarifiers), which reduces its loss to 0.14%.

3.2 Technological modes of processing molasses of various quality

Modern technology for the production of yeast imposes requirements on the composition of molasses, due to the need to increase the yield of yeast in the commercial stage to 80-90 ° / o per raw material and to maximize the production of yeast from each line of yeast-growing apparatus.

In molasses with a high carbohydrate content (more than 50%), there are few non-sugars necessary for building yeast cells: ash, nitrogen and biotype. In this regard, the ratio of the mass of the listed substances to the mass of sugars significantly decreases, and the excess sugar is spent not on the accumulation of biomass, but is fermented with the formation of alcohol.

Normalization of the composition of defective molasses

When processing molasses containing an insufficient amount of nitrogenous, growth and ash substances, it is necessary to add the missing components. Normalization of the nutrient medium composition leads to stabilization of the yeast yield, and to an improvement in the quality of the finished product.

When growing yeast according to periodic schemes, the nutrient medium is normalized by adding biotype sources (corn extract or destpobiotin), potassium and magnesium salts at the beginning of the growing process. Complete corn extract is served at the rate of 6%, and potassium salts at the rate of 3.5% potassium in molasses containing 46% sugar.

Normalization of the nutrient medium when growing yeast according to a continuous (for example, daily) scheme is carried out as follows: corn extract is served during loading (folds) of the yeast-growing apparatus at the rate of 6%, and potassium salts 3.5% (K2O) to molasses consumed in the storage period. The second time, corn extract and potassium salts are added at the beginning of the outflow period of the medium based on the molasses processed for 6 hours. Subsequently, the missing ingredients are added after 6 hours of the outflow of the medium based on the molasses processed over the next 6 hours.

4. OBTAINING YEAST PURE AND NATURALLY PURE CULTURE

Yeast production begins with a pure yeast culture. At the majority of domestic enterprises, pure culture of yeast (uterine yeast) is obtained according to the VNIIHP regime.

4.1 Scheme of obtaining uterine yeast according to the VNIIKhPa regimen

Culture media. Yeast of a pure and naturally pure culture must have high propagation energy, therefore, for their cultivation, nutrient media rich in organic nitrogen, growth and mineral substances and microelements are used. These nutrient media include malt wort, which is why it is the basis of the nutrient medium used for the propagation of yeast in laboratory stages. In the laboratory of the plant, yeast is produced in four stages.

In the first three laboratory stages, yeast is grown on a fortified medium, which is prepared as follows. To 2000 ml of malt wort with a concentration of 16-18% DM, add 450 ml of tomato or carrot juice, 50 g of glucose, 50 g of maltose and 50 ml of yeast autolysate (2%). The total concentration of the medium is adjusted with water to I2-14% DM, and the pH to 4.8-5.0.

Instead of malt wort, malt extract can be used to prepare the culture medium. Tomato or carrot juice can be replaced with grape juice, but glucose is not added, since this juice contains enough of it for yeast to multiply.

The culture medium is poured into sterile dishes: into four tubes of 5 ml of fortified wort, four small flasks - 50 ml each, four large flasks - 500 ml each. The medium is sterilized in an autoclave in accordance with the general rules of microbiological technology (0.05 MPa for 30 minutes). The medium, which does not contain sugars (for example, yeast water), is sterilized at a pressure of 0.1 MPa for 60 minutes.

The sterilized medium is checked for sterility, for which it is placed in a thermostat at a temperature of 30 ° C for 72 hours. It is considered sterile and is used to obtain CC if it does not become cloudy during this time. Glassware and filters are sterilized with dry steam in an oven at 160 ° C for 60 minutes.

In the last laboratory stage, yeast is grown on mixed media. For its preparation, take 10 liters of malt wort or fortified medium with a density of 12-14% DM, add 5 liters of molasses solution containing 30-32 DM, 25 g of diammonium phosphate and 5 liters of water. The medium is poured into two flasks, 7 l each. Carlsberg and sterilized in an autoclave at 0.05 MPa for 6.0 min.

In the workshop of pure cultures and at the production stage, the yeast CHK and ECHK are grown on a molasses solution with the addition of nitrogen and phosphorus nutrition, growth substances, etc. mineral salts.

Cultivation of ChK yeast in laboratory conditions. Reproduction of a pure culture begins from a pure culture of yeast obtained in test tubes from VNIPKhP, or from a museum culture of a yeast plant. ChK yeast can also be obtained from dried yeast, which is currently the case at a number of domestic plants producing dried yeast.

Growing yeast in the Cheka workshop. It is carried out in the following three stages - the stage of a small inoculator (MIN), a stage of a large inoculator (BIN), and a stage of ChK-1. The volumes of these apparatuses increase from stage to stage, and the amount of yeast mass also increases.

All stages of the ChK workshop are non-inflow, i.e. all nutrients and water are supplied at the beginning of the growing process (at loading).

Cultivation of ChK yeast in production (ChK-II stage). Unlike the previous stages in the production, yeast is grown by the air-inflow method. The main nutrients (molasses solution, nitrogen, phosphorus-containing salts) and water are fed into the apparatus continuously, while growth and mineral substances (potassium chloride, magnesium sulfate, etc.) are fed into the apparatus. This stage usually takes place in an apparatus with a total volume of 30 or 50 m3. The active acidity (pH) is adjusted using an ammonia solution supplied instead of ammonium sulfate in an amount equivalent to nitrogen, maintaining it in the range of 4.5-5.0.

Obtaining yeast ECHK. Pure culture yeast serves as a seed for growing naturally pure culture yeast.

Previously, ECHK yeast was obtained in three stages, of which the first two were conducted in a non-inflow mode, and the last one - in an air-inflow mode. At present, a more promising method for producing ECHK yeast in two stages is recommended. This method has several advantages over the previous one. With this method, the cycle time is reduced, the likelihood of infection of the culture is reduced, the number of workers is reduced, containers are released, the quality of the culture is improved (its enzymatic and generative activity, as well as storage resistance).

With modern two-stage yeast production, at the first stage, they are grown in the Cheka workshop according to the no-supply mode, at the second - in the production department according to the air-supply method.

Stage ECHK-1. It is known that growing yeast on an infected crop reduces the economic effect of using raw materials and the quality of finished products. To cleanse the yeast sown in the yeast-growing apparatus from bacterial infection, the uterine yeast is subjected to acid treatment with sulfuric acid or lactic acid. Acid * treatment is carried out in a special container equipped with a stirrer, where 100 liters of yeast milk (50 kg of yeast with 25% DM) is placed and, during continuous operation of the mixer, either 0.6-1.0 liters of previously diluted (1: 4) concentrated sulfuric acid (density 1.84). so that the acid bath is 25-30%, or 2.5 liters of 40% lactic acid. The medium is kept for 40-60 minutes with continuous stirring, after which it is inoculated into a yeast-growing apparatus, which was previously loaded with a nutrient medium.

When loading, about 4 m3 of water is taken into an apparatus with a capacity of 7.5 m3 and 600 kg of sterile molasses are added in the form of a solution with a density of 35-40% DM; 8.3 kg of ammonium sulfate; 4.3 kg of diammonium phosphate; 1.5 kg of potassium chloride; 0.5 kg of magnesium sulfate and 0.12 g of destiobiotin. The contents of the apparatus are mixed well, water is added so that after inoculation with yeast, the initial density of the culture medium is 10% DM, and the volume is 5.6 m3.

The cultivation process is carried out at a temperature of 28 - 30 ° C, pH 4.5-5.0 and constant aeration (30 m3 / h per 1 m3 of medium) until fermentation of the culture medium to a density of 3.0-3.5% DM ... The result is 230 kg of yeast, which serves as the seed for the second stage.

Stage ECHKII. It is carried out in an apparatus with a capacity of 30 or 50 m3 at a temperature of 28-3 ° C; The pH of the medium is maintained at 4.5 and is adjusted with an ammonia solution supplied instead of ammonium sulfate. During the entire process, the medium is aerated with air.

4.2 Isolation and storage of uterine yeast

At the end of ripening, CHK yeast is sent for separation. Isolation of yeast is carried out on separate separators according to a two-stage scheme. The yeast separated on the first separator is continuously transferred without delay to the second separator for thickening. Cold water for washing the yeast is fed to the intermediate collector after the first separation and to the second separator. Yeast washed and let to a concentration of 400-600 g / l, called; yeast milk, sent to the collection, in which they are stored at a temperature not exceeding 6 ° C.

Further condensation of yeast milk is carried out in vacuum filters.

Yeast ECHK is usually stored in compressed form or in the form of yeast milk (suspension of yeast in water), as well as in a dried state at an optimum temperature of 2-4 ° C.

Recently, the method of storing yeast Ch and ECHK in the form of yeast milk has found wide acceptance in the industry. It is the most promising, since it allows you to preserve properties valuable for uterine yeast - generative activity and culture purity.

The generative activity of uterine yeast, stored in a pressed form, is stable only during the first 10 days, with further storage it deteriorates. For example, if the value of generative activity in the original uterine yeast was 0.233, then after 10 days of storage in pressed form it increased to 0.237, and after 20 days it decreased to 0.230 and after 30 days - to 0.226. When storing yeast in the form of yeast milk, the generative activity of yeast improves during the entire period of snoring and after 10 days it increases to 0.238, after 20 days - to 0.248, and after 30 days - to 0.250.

When storing uterine yeast in the form of yeast milk, the enzymatic activity and purity of the culture are also preserved better, while when storing yeast in pressed form, along with a decrease in generative activity, a gradual increase in the bacterial microflora of yeast is observed, which sometimes reaches 50% (according to the ratio of colonies at sowing on Petri dishes). Extraneous microflora mainly consists of lactic acid bacteria and molds.

4.3 Indicators of the quality of the yeast CK and CK

The mother yeast should be a pure culture of saccharomycetes without admixture of extraneous yeast fungi and bacteria, especially putrefactive ones.

When microcopying, large round and oval cells of uniform size are visible. When sowing them on a liquid medium containing sodium acetate, after 5 days a film should not appear (a sign of the presence of non-saccharomycetes), and on solid media, colonies of yeast-like fungi and bacteria should not appear.

CHK yeast should contain 1.3% phosphorus and 2.5% nitrogen, and ECHK yeast - 1.0% phosphorus and 2.0% nitrogen and have high generative activity. The growth rate of active uterine yeast is 0.200-0.350. The generative activity of HK yeast depends on the method of its cultivation. Respiratory type yeast (aerobic, obtained by the air-inflow method) has a higher ability to multiply and grow in comparison with fermentative type yeast (anaerobic, obtained with a slight aeration of the medium). At the same time, cells are formed containing different amounts of biotin, metachromatin, RNA (ribonucleic acid), DNA (deocenribonucleic acid), polyphosphates and differing in composition. Active uterine yeast should have the following characteristics:

Yeast CHK - lifting force 35 - 40 min, maltase activity 70 - 90 min, osmosensitivity no more than 20 min,

Yeast ECHK - lifting force 40-50 min, maltase activity 70-100 min, osmosensitivity no more than 10 min.

The tenacity of good uterine yeast usually exceeds 72 hours.

In addition, yeast of pure and naturally pure culture should contain at least 10% of large cells, no more than 25% of small cells, no more than 10% of budding cells.

5. TECHNOLOGICAL PROCESSES AND MODES OF CULTIVATION OF COMMERCIAL YEAST

5.1 Growing yeast in dilute media

At domestic factories, commercial bakery yeast is usually grown according to the VNIIHPa scheme in two stages (seed stage B and commercial C) with a dilution ratio of 17 raw materials. Polish People's Republic. This is due to the separation of stage B seed yeast in these plants.

Growing yeast in factories with domestic equipment

Stage B. Inoculated yeast is obtained in yeast-growing apparatus with a total volume of 30 m3. The loading of the apparatus is carried out in the following order: water is taken into the yeast-growing apparatus, molasses and ammonium sulfate are added in the form of solutions; then served 215 kg of yeast ECHK in the form of yeast milk. At the end of the sowing, growth substances, viburnum chloride are supplied and the supply of nutrients begins.

In the process of growing yeast, the temperature is maintained at 30 ° C, the amount of air is 80 m3 / h per 1 m3 of medium in the apparatus. In this stage 1100 kg of yeast are accumulated in 11 hours. Ripening of yeast in stage B is not provided.

Stage B. Commercial yeast is obtained in yeast-growing apparatus with a capacity of 100 m3. The inoculation material is the entire contents of apparatus B.

Yeast is produced according to the technological scheme with a 20 or 12 hour propagation period. In the yeast-growing apparatus B, during the first 7 hours, the "working" biomass is accumulated by the air-inlet method (accumulation period). Then, a continuous outflow of it into the selection apparatus (sampling period) begins, where the yeast, under conditions of slight aeration and without the addition of nutrients, matures for 1 hour, after which it enters the separators for isolation.

Simultaneously with the outflow, nutrients (solutions of molasses, salts and water) enter the yeast-growing apparatus according to the program. In necessary cases, growth substances, potassium and magnesium salts are supplied. The amount of medium withdrawn on an hourly basis corresponds to the amount of liquid entering the yeast-growing apparatus, so the level of the medium in it remains constant. The amount of yeast in the main yeast-growing apparatus must also be constant (the yeast growth is taken into the selection apparatus).

Soda, clarified molasses solution, ammonium sulfate solution are collected in a yeast-growing apparatus with a volume of 100 m3, after which the entire contents of apparatus B are transferred; air is supplied simultaneously. After that, growth substances and potassium chloride are fed into the apparatus and the influx of molasses and salts begins. The air consumption in the apparatus is 100 m3 / h per 1 m3 of the medium. At the beginning of the process, the pH of the medium is set to 4.5, at the end of 5.5 to 5.8. By the end of the accumulation period, 3400 kg of yeast is accumulated and the entire useful volume of the stage B apparatus is filled.

From the 8th hour, a gradual selection of the culture medium into the selection apparatus at 11 m3 / h begins, where the aeration of the medium is reduced (the air flow rate is 40-50 m3 / h per 1 m3 of the medium). During the selection period, molasses, ammonium sulfate, and diammonium phosphate are fed into the main yeast-growing apparatus hourly in the form of solutions. The sampling period lasts 12 for a 20 hour yeast breeding period and 4 hours for a 12 hour period.

When the plant operates according to the regime with a 20-hour propagation period, 9300 kg of yeast are obtained from one apparatus.

Growing yeast in factories with equipment manufactured by Poland.

The factories are equipped with yeast-growing plants with a capacity of 100 m3. The yeast is grown in a 12-hour four-step pattern.

Commercial yeast is also grown in two stages.

Stage B. Yeast is grown in an apparatus with a total volume of 100 m3. The apparatus is loaded in the following order: water is taken into the yeast-growing apparatus, molasses and ammonium sulfate are added in the form of solutions. Then serve 620 kg of yeast ECHK in the form of yeast milk. Then add growth substances, potassium chloride and begin the flow of nutrient solutions. Potassium chloride and magnesium sulfate are consumed depending on the content of these substances in molasses and water and are added at the beginning of the yeast growing process.

Stage B yeast is separated in separate separators and stored in yeast milk tanks.

Stage B The accumulation period of the commodity stage lasts 7 hours. During this time, 4000 kg of yeast is accumulated both during the operation of the plant according to 12- and 20-hour schemes.

Water is taken into a yeast-growing apparatus with a volume of 100 m3 and molasses, ammonium sulfate and 1200 kg of stage B yeast in the form of yeast milk are fed in the form of solutions.

From the 7th hour, the period of selection of the medium begins, which lasts 4 hours when working according to the scheme with a 12-hour reproduction period and 12 hours with a 20-hour period. 11 m3 of the medium is taken into the selection apparatus every hour. In the yeast-growing apparatus, molasses, ammonium sulphate and water are also served in the form of solutions. Growth substances and KC1 are served at the 6th and 12th hour of fermentation (20-hour period). A total of 6,000 kg of commercial yeast is obtained when operating according to the scheme with a 12-hour breeding period and 10,000 kg of yeast according to the scheme with a 20-hour period.

5.2 Yeast maturation process

The process of growing yeast ends with its maturation. The quality of baker's yeast largely depends on the ripening stage. During this process, a restructuring of enzyme systems occurs from active synthesis of biomass to metabolic processes that support only normal cell functions.

By the end of the yeast cultivation process, when the supply of nutrients is stopped, the yeast-growing apparatus contains yeast cells of different ages, with different biological activity (old, daughter cells that have already given several generations, and young, just budded, as well as mature cells). Their ratio may be different, and this is largely due to the mode of conducting the technological process and the activity of the original culture. Daughter cells are in the stage of forming enzyme systems. Young cells have an active enzyme system aimed at protein synthesis. During the budding period, they are characterized by reduced durability. For synthesis, they use the nutrients contained in the mash. In mature cells, enzyme systems are balanced. Under certain conditions, such cells can retain their inherent properties for a long time, so the ripening process should provide the maximum number of mature cells (budding should be completed).

The yeast ripening regime acquires especially great importance when working according to the air-flow method, since cells with an active enzyme system aimed at the synthesis of biomass enter the selection apparatus all the time.

During maturation, cells consume residual nutrients. The budding process ends. The budding cells grow and the biomass increases mainly due to cell growth.

5.3 Isolation of yeast

At the end of the cultivation and maturation process, the yeast is isolated from the culture medium, first on separators, then washed several times with cold water, condensed and yeast milk with a yeast concentration of 300-700 g / l is obtained. Then it is sent to vacuum filters for the final isolation of the yeast.

Separation. Several methods are known for isolating and washing yeast.

Yeast washing in one washing apparatus with continuous water supply and continuous separation of washing water on separators is carried out until the yeast is washed from the mash. Then the water supply to the washer is stopped, the washed yeast milk is condensed and fed first to the milk collectors, and then to the final separation.

Washing in two washers. The yeast milk obtained after separating the mash from the yeast is washed first in one, then in another washing apparatus, after which it is concentrated on the same separators and sent to the yeast milk collectors, and from there to filter presses for the final separation of the yeast from the washing water.

Two-stage separation. The yeast is separated and thickened in different separators. The culture medium of the yeast of the yeast-growing apparatus is fed to the first stage of the separators. The separated yeast is pumped through an intermediate tank, into which cold water is supplied for washing, to the second stage, where additional washing and thickening of the yeast takes place. The washed and condensed yeast is sent to the collectors of yeast milk, in which it is stored at a temperature not exceeding 6 ° C (the optimum temperature is 2 - 4 C).

Three-stage separation. Separation of yeast from the medium, washing and thickening of yeast milk take place on different separators. At the first stage, the yeast is separated from the mash. Unwashed yeast through an intermediate tank, which simultaneously receives cold water for washing, is fed to the second stage of separators, where the yeast is separated from the washing water. Then they enter the second intermediate tank, which is also supplied with cold water. Here the yeast is washed again, after which, together with the washing water, they are pumped to the third stage of the separators, where the yeast is thickened to a concentration of 450-700 g / l.

The most effective in comparison with the first two are the stepwise separation schemes, which provide better washing, thickening and high quality of the finished yeast.

5.4 Forming, packaging and transporting yeast

The yeast pressed on a vacuum filter or filter press goes to the forming machine, where it is moistened if necessary to give the required consistency of the yeast mass.

The yeast is sent to packing and filling machines, forming the yeast mass in the form of rectangular bars 1000.500.100 and 50 g.

5.5 Yeast storage

At domestic yeast factories, baker's yeast is mainly stored in refrigerators, wrapped in special paper, at a temperature of 1-4 ° C and a relative humidity of 82-96%.

5.6 Drying yeast

Dried baker's yeast is obtained from compressed yeast. Drying yeast is one of the most effective ways to preserve its enzyme systems, since it cannot be stored for a long time in compressed yeast.

The essence of the yeast drying process is to remove water from the pressed yeast. At the same time, their moisture content decreases from 72 to 8-10%.

The main task of the drying process is to remove only free moisture. If you remove chemically bound moisture from the cell, the structure of the protoplasm will be disrupted and the cell will die.

Chemically bound moisture n is that residual moisture of dried yeast (7-8%), which is not removed during drying.

A number of methods for drying yeast are known: in a sedentary layer, in suspension, by spraying, sublimation, under residual pressure.

In all dryers, yeast is dried with heated air. However, the air temperature is different due to the design of the dryers. For example, in a vacuum dryer, the temperature of the yeast 30 ° C in the first period of drying is maintained when the drying air is heated to 60 ° C due to strong evaporation of moisture. In chamber and belt dryers, evaporation is slower than in a vacuum one, therefore, it is possible to maintain a temperature of 30 ° C in the yeast when the air entering the dryer is heated only to a temperature of 45-48C. In the spray dryer, due to the very fast drying of the yeast, no overheating of id is observed even at an inlet air temperature of 140 ° C.

The yeast drying process consists of the following operations of feeding compressed yeast into a forming machine, shaping them in the form of granules, feeding yeast granules into the dryer, drying process, feeding dried yeast into a "cooling hopper, packaging finished products

6. APPENDIX

Technological scheme of yeast production using mash: 1 - collectors for molasses: 2 - scales; 3 - collection for dilution of molasses; 4 - clarifier: 5 - collection for diammonium phosphate solution; 6 - collection for a solution of ammonium sulfate; 7 - supply collectors for clarified molasses; 8 - separation of pure yeast culture; 9 - yeast-growing apparatus of the CHK and ECHK yeast; 10 - yeast-growing apparatus of stage I of commercial yeast: 11 - yeast-growing apparatus of stage II of commercial yeast; 12 - selection apparatus; 13, 15 - yeast separator; 14 - washing tanks: 16 - filter press or vacuum filter: 17 - hopper: 18 - forming and packing machine: 19 - sand filter; 20 - collection for mash sent into circulation; 21 - microwave apparatus for sterilizing the mash sent into circulation; 22 - measuring tank for brew; 23 - collection of yeast milk of uterine yeast; 24 - collection of commercial yeast yeast milk.

Yeasts are living organisms that have long been cultivated by humans and used to prepare food and drinks. If you ask what yeast is made of, then it will be impossible to answer in one word. The fact is that they existed on earth even before the birth of human civilization.

Unique microorganisms

Yeast is a living microorganism that can feed and reproduce. They are very sensitive to changes in temperature and food composition.

Yeast mushrooms exist in nature everywhere. They feed on biological raw materials, and in the process of metabolism, that is, fermentation, they produce new chemical compounds. The number of these microorganisms in nature is so great that if we compare it with the number of grains of sand in the seas and on land, then yeast spores will be many times greater. Needless to say, there are also a great many varieties of yeast fungi. Some are good for our health, while others are harmful. All live yeast intensively emit carbon dioxide and alcohol fractions.

Types of mycetes used in the production of bread dough

In the food industry, and in our case in the baking industry, only some species are used, namely those that, eating a nutrient substrate, emit a large amount of carbon dioxide. It is thanks to the bubbles of this gas that the bread turns out to be porous. Its quality is even determined by how the loaf behaves, if you squeeze it until the opposite sides join and release it. If it straightens to its original state, it means that the bread is of high quality.

There is also a lot of yeast of this class. In the modern baking industry, mushrooms from the Saccharomycete family are most often used for the manufacture of soft bread.

Baker's yeast and leaven

What yeast is made of for baking bread, every baker knows. It is best to start a conversation about bread yeast with a story about leaven. It is mentioned in ancient books dating back several millennia. Sourdough and baker's yeast are one and the same thing. Bread leaven is a product that has always been treated with special care. All actions with her were surrounded by many signs and rituals. The products from which the initial sourdough was made was chosen with great care. The most successful was kept and cultivated, passed on from generation to generation.

Quality bread is a guarantee of good health

The fact is that different types of mushrooms exist under different conditions. And even if the dough made from yeast bred on the same raw material turns out to be very tasty, this does not mean that this leaven will show itself in the same way the next time it is used. There is always the possibility that the original mushroom culture has been replaced by a new one. This is not visible to the naked eye, but the next batch of bread may turn out to be tasteless and even unhealthy. It is no coincidence that in ancient times one of the ways to destroy an enemy tribe or other community was this. The scout penetrated the enemy's camp and spoiled the leaven, since it was believed that bread and water were the most important food for a person. Health and life depend on the quality of these two products. What does yeast do to the product? They change its appearance, consistency, composition and properties. To understand the mechanism of their work, you need to figure out how and from what baker's yeast is made.

Hop sourdough

Take one glass of hop cones, cover with two glasses of water and put on fire. Simmer until the liquid is halved. Cool to 37-40 degrees and strain. Put one to two tablespoons of sugar and half a glass of flour in the hop broth. Cover with gauze. This is necessary in order for the yeast to receive oxygen, otherwise they will die. Place the container in a dry, warm place away from direct sunlight and drafts. In two days, you will have a culture of baker's yeast, the very sourdough that, taking a little, can be reused in baking. Typically, 1 kg of flour requires 50 to 100 g of sourdough.

Unusually tasty bread is made from barley malt sourdough with honey and hops. Malt is flour milled from sprouted and dried grains. Its microbiological composition is fundamentally different from the composition of flour made from polished grain.

The secret to delicious beer - malt, hops and yeast

Hops and barley malt are what brewer's yeast is made from. The brewing process is extremely simple. Whole grain of barley is soaked for germination. Rye grains are also what beer yeast is made of. However, due to its specific taste, barley is more commonly used. It is imperative to germinate. Yeast does not like unsprouted grain - it contains a lot of starch and little sugar. When the embryo is activated, that is, germination, the amino acid present in it, amylase, is activated in the grain. Amylase also hydrolyzes starch into mushroom-digestible sugar. The sprouted grain, called malt, is allowed to rest for a while to ensure the most complete fermentation, then ground, mixed with water and boiled with the addition of hop cones. The result is wort - an excellent feed for brewer's yeast.

Two types of yeast are used for beer. Some ferment the drink on the surface and live at a temperature of + 14-25 degrees Celsius. This so-called top yeast forms a frothy head on the surface of the wort. At the end of the process, the mass fermented with horse yeast sinks to the bottom. There, another colony begins to work - grassroots yeast. They work in colder conditions - at temperatures from +6 to +10 degrees.

The difficult art of the baker

In the olden days, before the advent of electric ovens and refrigerators, the process of making bread and preserving the leaven was almost a mystery. The sourdough was not lent, and when they made bread (this process took at least two days), they tried not to make noise, not to slam doors and dampers. We watched the dough in order to have time to knead it in time and not let it sour. Failure to comply with the prescribed conditions is fraught with the development of another yeast culture, since different yeasts require different temperatures, density and composition of the nutrient substrate. Good yeast can be replaced by bad yeast. It was believed that a bad person's bread is always tasteless. They tried to buy bread only from a certain master.

Yeast is a source of vitamins essential for health

Yeast ferments the bread base in such a way that it changes in chemical composition. Good bread consists only of flour, water and sourdough, in which there is a small amount of sugar for a pleasant taste of bread - a consequence of the fermentation of flour with yeast. Yeast enriches bread with B vitamins and vitamin D. When baked in a Russian oven, most of the nutrients were retained. It is unclear if this was known in the olden days, but the oven temperature had three characteristics - before, after and during baking. The mild, even heat during the preparation of the bread was below the boiling point of water. In very high temperatures, the product burns on the outside and does not bake on the inside.

Modern dry yeast, unlike sourdough, is very convenient, as it is less capricious and more stable. Even an inexperienced housewife can bake excellent bread from them. In this regard, a natural question arises: "And what is dry yeast made of?"

Sugar, water, air and a temperature of 30-50 degrees - the optimal environment for saccharomycetes

Since yeast is living organisms, by and large, they are not made, but grown from the usual yeast fungi used in the manufacture of bread - Saccharomycetes, that is, bacteria that feed on sweet things - sugar, sucrose, fructose, etc. for baking yeast feed, beet mass waste is used - molasses. Sugar beet is what raw yeast is made of at domestic enterprises.

Molasses

Yeast grows very quickly on this product. Molasses, also called black molasses, is a thick, viscous liquid of very dark color. One ton of substrate grows up to 750 kg of yeast. Molasses from beets or sugarcane is what the pressed and instant baker's yeast is made of. Currently, with large production volumes and high demand for ready-made yeast, these are the most common bases for the cultivation of saccharomycetes. However, these mushrooms can grow well on other mushrooms rich in natural sugars. If you use a starchy substrate - potatoes or grain, then it should be fermented.

The safety of a modern proving product

Thus, it is obvious: what baker's yeast is made of in modern production does not pose any harm to health. With proper storage and use of modern dry fast-acting yeast, you can not be afraid that new crops that are harmful to health will develop in them, because in food production only those yeasts are used that have been well studied for resistance to various transformations. Moreover, they are significantly safer than home-made "wet" sourdough. In dry yeast, metabolic processes are in a static state. Metabolism begins only with the addition of sugar and liquid - water or milk.

Having figured out what yeast is made of for baking bread, you have to decide which one to give preference - raw pressed or dry instant (instant).

Pressed

The yeast mass grown on molasses is separated, that is, it is strained. Water is added to the yeast and separated again. As a result of several procedures, the yeast mass acquires a grayish color and a viscous consistency. The vacuum apparatus removes excess moisture. This process is called sublimation. The resulting gray, plastic, clay-like substance is cooled, divided into portions, formed into briquettes, packed into and sold. Store such a product in the refrigerator at a temperature of minus 2 degrees Celsius and an ambient humidity of about 72-75%. The shelf life is 12 days. In the retail sale of such yeast nowadays you can not always find. In this case, I would like to know what they are made of if they are such a rare product. After all, we very often tend to think that the products that adorned store shelves 20 years ago were much better than the current ones. It is possible that this is so, but not with regard to yeast.

It turns out that the point is not what the pressed bakery yeast is made of, but the fact that they are extremely inconvenient to use. It is extremely difficult to withstand the required humidity and temperature in the dry cold conditions of a modern household refrigerator. The 12-day period also limits the housewife. Usually, yeast dough is baked on weekends. A whole pack of compressed yeast is too much for one time. For a family of 4, even with invited guests, half a pack is more than enough, and until next weekend, such yeast cannot be kept active.

Dry

They have long and firmly taken their place in our kitchens. It must be said that, despite the modern electronic technologies that are used by the manufacturers of this product, dry yeast was known even in pre-Christian times, when the leaven was dried in order to preserve it during transportation over a long distance. What dry yeast is made of is no different from what pressed yeast is made of. This is the same sweet syrup and, in fact, the saccharomycetes themselves.

The process of their production is longer, because the grown and partially dehydrated yeast mass should be dried and turned into granules. There are three types of dry yeast. These are dry active yeast, dry active instant and dry active instant instant. Sugar syrup and saccharomycetes are what fast yeast is made of. Only the dewatering technology is different. If for ordinary dry yeast low-temperature drying is used according to the Russian stove technology, then the instant ones are dried in vacuum by sublimation. With the first method of drying, a product with a rather weak vital activity is obtained. Despite the fact that the life of such yeast is 12 months, they barely reach its end, so significantly losing the property of fermenting baking that it is advisable to buy them only at the beginning of the expiration date stated on the package. Therefore, when reading the accompanying inscription on the packaging, carefully study not only the information about what the baker's yeast is made of, the composition of the product, its calorie content, the name of the manufacturer, but also the date of manufacture of the yeast and its validity period.

Emulsifiers and antioxidants

If you are against the addition of emulsifiers and antioxidants to the product, then use compressed yeast or starter culture. However, do not forget that they may contain microflora and chemical elements that are not useful for health. Emulsifiers are added to the raw yeast mass before drying. All the thick mass is poured onto a pallet in a vacuum chamber. A vibration is created there, it separates the dried substrate into small fractions, which are then packaged into an Emulsifier and an antioxidant is added to the yeast to prevent unwanted growth of fungi and prevent them from sticking together before they are used in the dough. Do not think that these additives are included in the composition in order to harm our health. This opinion is deeply mistaken and very strongly smacks of amateurism and “yard competence” in matters of molecular chemistry. Sometimes you even hear this: “Everyone knows perfectly well what yeast is made of. The composition of good yeast is just saccharomycetes and nothing else! " However, vegetable oil is poured even into the pressed yeast so that it does not begin to actively multiply before it gets into the sweet solution. After asking what dry yeast is made of (the composition is described on the package), you can see that the product contains natural yeast, emulsifier E 491, antioxidant E 320, starch or rehydrating agent. Those cases where only yeast is included in dry yeast and nothing else, only indicate that the manufacturer did not indicate complete information about the composition of his product, and by no means about the absence of stabilizing and disinfecting impurities. People with a sense of humor say that fear of food can kill much faster than food itself. This also applies to food additives.

Making bread from dough mixed with instant instant yeast is a pleasure. The instant yeast "Saf-moment" has proven itself very well. Knowing what the Saf-moment yeast is made of, and this is indicated on the label, you have much more confidence in the manufacturer than if he had not written that a rehydrating agent was introduced into the yeast mass to control the moisture level. This yeast does not need to be diluted in sweet milk or sugar syrup. They will perfectly raise the dough if you pour them directly into the flour or knead into the finished dough.

Ode to Saccharomyces and Vacuum

What to prefer - yeast or sourdough, everyone decides for himself. However, we figured out what yeast is made of. It is very difficult, or rather impossible, to grow not saccharomycetes on sugar molasses, but any mushrooms dangerous to health. Alcohol and carbon dioxide released by these little workers destroy the pathogenic microflora, and vacuum sublimation and sealed packaging ensure the absence of unsanitary impurities. Sourdough is a good thing, but is it possible to make it as sterile?

The technological process of growing yeast consists of separate main stages: preparation of a nutrient medium, growing yeast, isolation, molding and packaging of compressed yeast, drying and packaging of dried products.

Preparation of the culture medium.

A nutrient medium is understood as solutions of molasses, as well as solutions of nitrogen- and phosphorus-containing salts. Thick molasses from molasses storage is transferred to collection 1, where its daily supply is stored. From the collector 1, the molasses is sent to the scales 2, from where, after weighing, it is transferred to the collector for diluting the molasses 3, where it is diluted with water. This process is called dilution. Then the molasses solution is fed to clarifiers 4, where it is freed from mechanical impurities - this process is called clarification. The clarified molasses is pumped into the supply collectors for molasses 7, from where it is fed to the yeast-growing apparatus.

Nitrogen- and phosphorus-containing salts are dissolved separately in special containers with water and used to feed yeast in the form of solutions, which are fed into yeast-growing apparatus from supply collectors for salts 5, 6. Separate tanks are used for each salt both for dissolving it and for inflow.

Growing yeast.

This stage is the main one in the production of baker's yeast. Cultivation of yeast is the process of multiplication of yeast cells, when from a small number of cells seeded into the nutrient medium, gradually, by a series of successive stages, a large amount of yeast is obtained, which is used in a number of industries, and primarily in baking.

The process of growing yeast consists of two stages: obtaining uterine and commercial yeast. The mother yeast is first obtained in the laboratory of the plant, and then in the workshop of pure cultures, for which yeast-growing apparatus 8 and 9 are used. First of all, pure culture yeast (CK) is obtained, and from them - naturally-pure culture yeast (NEC). A pure culture is a yeast grown from one cell, without admixture of foreign microorganisms. The first stages of CK yeast propagation take place in the laboratory of the plant, then in the workshop for pure cultures and, finally, in the production yeast-growing apparatus designed to breed a pure and naturally pure culture. A naturally pure culture is a yeast that contains a small amount of foreign microorganisms and is used as a seed for growing commercial yeast.

Commercial yeast at domestic yeast factories is obtained in two stages: stage B - seed yeast, which is grown in apparatus 10 and stage C - commercial yeast, which is grown in apparatus 11 with maturation in apparatus 12.

Isolation of yeast.

The grown uterine and commercial yeast is isolated from the culture medium (the medium in which they multiplied), washed with cold water and concentrated to a concentration of 500-600 g / l on special machines - separators 13, 15. For washing the yeast use special tanks 14. Condensed yeast is called yeast milk. After separation, they are sent to special collectors of yeast milk. Yeast milk of uterine yeast is placed in collectors 23, and commercial yeast - in collectors 24. During separation, up to 80% of the liquid is separated.

The final separation of the yeast from the liquid takes place on special machines called vacuum filters or filter presses (16), which are fed with yeast milk from collectors. In this case, the yeast acquires a dense consistency and the form of plates or layers of various thicknesses.

Yeast forming and packaging.

Yeast plates from vacuum filters or filter presses are fed by a conveyor into the bunker 17 of the forming and packaging machine 18, where they are molded into bars of various weights and packed into special label paper.

Drying and packaging of dried products.

In some yeast factories, compressed yeast, bypassing forming, is sent to drying units (dryers), where they are shaped into vermicelli, crushed and then dried. Dried yeast is in the form of granules.

Dried yeast is packed by hand in kraft bags with a polyethylene liner, or in boxes with parchment paper, or packaged on special machines in hermetic packaging - cans.

Characteristics of products, raw materials and semi-finished products. Yeast - unicellular microorganisms belonging to the class of saccharomycete fungi. The yeast cell contains on average 67% water and 33% dry matter. The dry matter of the yeast cell contains 37 ... 50% proteins, 35 ... 40% carbohydrates, 1.2 ... 2.5% crude fat and 6 ... 10% ash substances.

The quality of baker's yeast is determined by the requirements of the bread technology. They should have a dense consistency, break easily, have a gray with a yellowish tinge and a characteristic yeast odor, fresh taste, moisture content no more than 75%, acidity (in terms of acetic acid) no more than 120 mg per 100 g of yeast on the day of production, and no more than 360 mg after 12 days. Resistance at a temperature of 35 ° C of yeast, developed in yeast factories, not less than 60 hours, and on alcohol - 48 hours, lifting force (rise of the dough to 70 mm) - not more than 70 minutes.

It is planned to release dried baker's yeast of the highest and 1 grades in the form of granules, noodles, cereals or powder from light yellow to light brown. The moisture content in yeast of the highest grade is 8%, in yeast of the 1st grade - 10%. Dough rise up to 70 mm for premium grade - 70 min, for grade 1 - 90 min. Preservation from the day of production for dried yeast is at least 12 months for the premium grade and 5 months for grade 1.

Indicators of the quality of yeast, yeast milk (water suspension): concentration of yeast - not less than 450 g / l in terms of humidity 75%, lifting force not more than 75 minutes, acidity not more than 120 mg per 100 g of yeast per day of production and not more than 360 mg after 72 hours

Features of production and consumption of finished products. Yeast production is based on the ability of yeast cells (microorganisms) to grow and multiply. The technology of baker's yeast in yeast factories is based on biochemical processes associated with the transformation of nutrients of the culture medium with active aeration into the cellular substance of yeast. During aeration, yeast oxidizes the sugar of the nutrient medium to water and carbon dioxide (aerobic respiration). The heat energy released during this is used by the yeast for the synthesis of cellular matter and metabolic processes. Under aerobic conditions, significantly larger biomasses are accumulated in the substrate than during anaerobic respiration.

The composition and concentration of the nutrient medium for the cultivation of yeast determines the rate of their reproduction and the final yield of products. For the constructive and energy metabolism of yeast, sugars, nitrogen compounds, ash elements and atmospheric oxygen are used.

Baker's yeast is cultivated on molasses media diluted with water. Sugar of such a medium is easily absorbed by yeast. The theoretical yield of yeast biomass with 75% moisture content is within 97 ... 117% in relation to the mass of molasses containing 46% sugar. In factory conditions, the yeast yield is only 68 ... 92%.

Yeast is used in baking as a causative agent of alcoholic fermentation and baking powder. They are also used to obtain kvass, vitamins, medicines and nutrient media. Yeast factories produce pressed and dried yeast, as well as yeast milk. Only pressed yeast is produced at molasses distilleries. Liquid yeast and bread leavens are prepared directly at bakeries.

Molasses and distilleries produce 15% of baker's yeast from their total output. This yeast is obtained as production waste during the separation of mature alcoholic brew, 1 m 3 of which contains 18 ... 35 kg of yeast. The yield of compressed yeast is up to 3.5 kg per 1 dal of alcohol. The cost price of baker's yeast obtained at distilleries is 30% lower than that of yeast yeast.

Stages of the technological process. The process of obtaining baker's yeast in yeast factories consists of the following stages:

- preparation of the nutrient medium;

- growing yeast;

- isolation of yeast from the brew;

- forming and packaging yeast;

- yeast drying (if necessary).

Obtaining yeast from an alcoholic brew at distilleries consists of the stages:

- isolation of yeast from mature brew by separation;

- washing and concentrating the yeast suspension;

- ripening of yeast;

- final washing and concentration of yeast;

- pressing, forming and packaging yeast;

- storage.

Characteristics of equipment complexes. The line starts with a complex of equipment for the processing of raw materials, consisting of apparatus for the preparation of nutrient media, separators-clarifiers for molasses and steam-contact units for sterilization.

The leading complex of the line is represented by yeast-growing apparatus equipped with an aeration system for saturating the suspension with oxygen, and blowing machines.

The next complex of the line consists of apparatus for separating yeast, which includes yeast separators, filter presses and drum vacuum filters.

The most energy-intensive set of equipment for the line is drying plants, represented by conveyor belt dryers, installations with a vibrating boiling bed, as well as vacuum and freeze dryers.

The final complex of the line equipment consists of machines for forming and wrapping yeast briquettes.

In fig. 2.16 shows the machine-hardware diagram of the line for the production of baker's yeast.

The device and principle of the line. Molasses arrives at the factories in rail tank cars 1 ... It is poured into an intermediate collection 2 and pumped by a gear pump 40 to the collection 3 mounted on scales 4 ... Molasses through intermediate collection 5 flows into the molasses storage 6 ... Through an intermediate collection 7 molasses enters the mixer 8 , where it is diluted with water, acidified and then pumped 20 pumped into a sterilizer 9 ... Then the molasses goes to the heat exchanger for cooling. 10 and for cleaning in a clarifier 11 ... The purified diluted molasses is divided into two streams, one of which enters the supply unit 12 a nutrient medium for obtaining yeast CHK and ECHK, and the other into the apparatus 13 to obtain two stages of commercial yeast. From the collection 14 water, according to the technological regulations, is sent to various devices ( 15 …19 , 21 , 22 and etc.). In the workshop for pure yeast cultures, the culture medium is sterilized in a sterilizer 15 , after which it enters the inoculators of pure cultures: small 16 and big 17 .

Figure: 2.16. Machine-hardware diagram of the bakery yeast production line

Pure yeast cultures are grown sequentially in two stages in yeast-growing apparatus. Yeast of pure cultures ChK-1 and ECHK-1 is sent to the yeast-growing apparatus 18 , and yeast pure cultures ChK-2 and ECHK-2 - into the apparatus 19 ... Naturally pure culture 1 a yeast pump is fed to the separator for concentration 24 and further to the intermediate collection 25 ... In the second stage of concentration, a separator is used for this yeast. 26 , collection of concentrate 27 .

After cooling in the heat exchanger 10 yeast milk enters the yeast brewing apparatus 21 at the first stage of growing commercial yeast. From this apparatus, yeast mass with a significantly higher concentration of microorganisms through a separator 28 , collection of commercial yeast concentrate 29 pump is fed to the heat exchanger-cooler and then to the yeast-growing apparatus 22 to the second stage of obtaining commercial yeast. From the apparatus 22 yeast enters the selection apparatus 23 ... The thickening of commercial yeast goes sequentially in three stages in separators 30 , 32 and 34 ... In the first two stages, the yeast mass is washed with water and sent sequentially to the collectors 31 and 33 ... Condensed yeast milk collection 35 after cooling by a pump it is pumped to the vacuum filter 36 ... Further pressed yeast from the collection 37 go to automated lines for molding and filling. Air is an important technological factor in the production of baker's yeast. Filtered 38 air blowing machine 39 returns back to the technological cycle ( 16 …19 , 21 , 22 ). Exhaust air containing CO 2 and other impurities is removed from the apparatus into the atmosphere. Stations of nutrients, defoamers, antiseptic solutions are equipped with special measuring tanks 41 …45 ... From these measuring tanks, solutions of these substances are sent to the apparatuses 16 …22 .

One of the lucrative niches for small businesses is the production of various semi-finished products. These include various types of yeast. Yeast is widely used in winemaking, brewing, bakery and even alcohol. Their production process is quite simple and profitable. This allows you to recoup your initial investment within a year.

Our business valuation:

Initial investment - 10,000,000 rubles.

Market saturation is medium.

The complexity of starting a business is 8/10.

Yeast types

At the moment, all existing types of yeast can be divided into 2 large categories - pressed and dry. The first ones contain about 70% moisture. This does not allow them to be stored for a long time. For the same reason, their export is practically impossible. But on the other hand, most of the bakery shops are designed to work with them.

The second are dry granules, which must be dissolved in water before use. At the moment, for ease of use, a new type of dry yeast has been made - instant. There is no need to dissolve them in water before use. They are immediately added to the flour. All yeast produced in Russia must have a corresponding certificate of conformity.

Where to begin?

To open a yeast plant in Russia, you first need to find the necessary premises. Since this type of activity relates to food production, special attention should be paid to compliance with sanitary standards. This will be controlled by the relevant sanitary and epidemiological services. Therefore, at this stage, the easiest way is to rent a ready-made room intended for the production of food products.

In addition to sanitation, attention must be paid to the specifics of production. For example, yeast production technology requires compliance with a certain temperature regime. Therefore, the heat insulation of the workshop must be performed at the proper level. At the same time, do not forget about air conditioning systems. A temperature rise above + 40 ° will negatively affect the quality of the yeast.

If we distribute production by area, it will look like this:

1. Production line 280 m 2;
2. Premises for a pumping station not less than 48 m 2;
3. Power shop 48 m 2.

After preparing the production premises, you need to calculate the required number of personnel. For a small production, producing about 500 kg of products per day, 45-50 workers will need to be hired. Most of them, about 30-35 people, will be ordinary workers.

Equipment

Commercial yeast production involves the use of the following equipment:

1. Yeast. Or, in another way, containers for planting yeast grown in the laboratory. Their number depends on the volume of production.
2. Inoculator or, in a simple way, a vat for seeding. It grows yeast.
3. The skimmer. Its main purpose is to separate the foam formed during fermentation.
4. Transfer pumps.
5. Separators. With the help of them, the separation of yeast from the mash is carried out.
6. Washing tank.
7. Plasmolysis.
8. Dryer.
9. Packing line.

All of the above yeast making equipment can be used to make pressed, dry or baker's yeast.

Production technology

The production of baker's yeast is carried out using the same technology. The differences are only in the methods of their final processing. The technological scheme of their production consists of 3 main stages:

1. Growing. This stage is subdivided into 2 main processes. During the first, the uterine culture is grown. During the second, commercial yeast is grown.
2. Isolation from the brew. First, the flotation process takes place, that is, the yeast culture is removed from the mash. Then it is thickened in separators.
3. Dehydration. At this stage, the yeast is plasmolyzed and finally dried.

In general, the production of compressed yeast is reduced to creating favorable conditions for the growth of the yeast fungus. By favorable conditions is meant a controlled nutrient medium consisting of easily digestible sugars. The main raw material for the production of yeast is molasses and mash based on it. In the process of growing, yeast assimilates amino acids from them.

As they develop, they will absorb nutrients from it, so food has to be periodically added, and the mass itself will be enriched with oxygen. After reaching a certain volume, the growth of the mass is stopped forcibly. Next, the yeast is separated from the nutrient medium, that is, it is separated. The final final stage in the manufacturing process is the formation of the finished product.

Traditionally, the production of nutritional yeast in Russia is carried out by pressing. Pressed yeast briquettes are yeast cells isolated from the nutrient medium that have undergone special purification. They contain 68% water and 32% yeast cells.

Dry yeast is made in a similar manner. With one exception, other yeast strains with increased resistance to drying are used in the production process. During drying, the compressed yeast is passed through an extruder. It forms a kind of "vermicelli" from them, which is then cut into granules. The pellets themselves are then sent to the dryer, where they are converted into dry pelleted yeast under the influence of warm air.

The production of feed yeast is carried out in a similar manner, with one exception. The yeast strains used do not require sterile conditions. Their feature is also that they give a higher biomass yield. The production of alcoholic yeast also has its own characteristics. Wort from malt is used as a nutrient medium for them.

Perspectives

According to statistics, the yeast business is developing quite dynamically. On average, sales of such enterprises grow by 5-7 percent per year. This is due to the constantly growing sales market.

Most of the imported analogues of dry yeast imported into the territory of Russia have risen in price due to high customs duties, which made them uncompetitive in comparison with the products of domestic producers. Therefore, the yeast business has a future.

Success secrets

The secret of the success of yeast production, like any other type of business, lies in the quality of the products. Also for large consumers the stability of supply is very important. To reach the required level, the technology needs to be constantly improved by introducing new ideas into it.

It is also necessary to have in its staff a team of highly professional technologists who will closely control the production process and monitor the quality of products.