Ways to increase the lifting force of yeast

[Ways to increase the lifting force of yeast]

Ways to increase the lifting force of yeast

Yeast - This is a kind of microorganisms, yeast fungi, capable of converting some organic compounds into others, simpler in structure. Yeast is used in the food industry: in winemaking, brewing, cheese making and baking - depending on the type of product, several types of fermentation are used, which means several types (strains) of different yeast.

Most often pressed and highly active (instant) yeast is used in the baking industry.

Compressed yeast Is a technically pure culture of Saccharomycescerevisiae yeast, formed into briquettes with a moisture content of 67 - 75%. The culture is prepared by cultivation on special nutrient media by constant accumulation of the biomass of uterine and seed yeast under conditions of intensive aeration of the medium until commercial yeast is obtained by pressing or vacuuming. One gram of compressed yeast contains 10-15 billion cells.

Instant yeast - highly active dried yeast that does not require regradation before being added to the dough, prepared on the basis of certain strains of saccharomycetes using modern cultivation conditions, drying methods and protective additives and / or emulsifiers.

The terms and conditions of yeast storage affect their fermentation activity.

Dry yeast, especially highly active "instant" ones, much less often than pressed ones, have a low lifting force. But they cannot be frozen or used in the formulation of the dough, which includes ice, since the death of yeast cells occurs (it is possible to use instant yeast after dissolving the ice in the dough). It should also be borne in mind that packaged in vacuum bags, they can be stored for up to 2 years in their original (undamaged) packaging, with practically no decrease in fermentation activity, but after opening the package, they must be used within 3 - 4 days.

Compressed yeast is the most dependent on storage conditions. They can be frozen, but before use, the yeast is thawed at a temperature of 0 ... + 4 ° C. The pressed yeast is stored at a temperature of 0 ... + 4 ° C for 24 or 30 days; at a temperature of + 3 ... + 6 ° С for 12 days.

Brown spots that may appear during storage of the compressed yeast are the result of autolysis and represent dead yeast cells. They usually occur when the yeast is stored for too long or when the storage temperature is too high. There are no nutrients for yeast cells in the pressed yeast bar. Storage at a temperature of about 4 ° C limits the activity of cells, but in warmer conditions, oxidation processes begin to occur and cells are destroyed. This means that when using such yeast in the dough, gas evolution will be reduced. Proofing time is significantly increased when the pressed yeast is stored at 10 ° C and 15 ° C. After storage for 14 days at 15 ° C, the time required to proof the dough doubled.

In addition to reducing the gas-forming ability, it is possible to release the contents of damaged cells through destroyed membranes. Yeast cells contain a number of enzymes and other chemicals. The release of proteolytic enzymes and glutathione (a reducing agent) has a bad effect on the baking process, since these substances affect the structure of the gluten of the dough and weaken it.Subsequently, such a dough exhibits insufficient gas-holding capacity, that is, a decrease in volume and a more open porous structure is observed in the finished product. In more severe cases, the dough can become sticky and thus difficult to process.

Therefore yeast with low lift should be pre-activate to strengthen the structure of protein molecules, reduce the activity of proteolytic enzymes, and neutralize glutathione.

To activate yeast, it is most expedient and effective to use liquid nutritional mixtures containing organic substances, in particular carbohydrates, hydrocarbons, organic acids and mineral salts.

Mix for activation using malt and soy flour.

The mixture consists of flour, water and a brew fortified with unfermented malt and soy flour. For brewing: wheat flour - 1.3 ... 2.0 kg; water (95 ... 98 ° C) - 4.0 ... 6.0 l; white malt - 0.2 kg For the preparation of the activation phase: brewing - 5.5 ... 8.2 kg; cold water - 5.5 ... 5.7 l; wheat flour - 1.3 ... 2.0 kg; soy flour - 0.5 kg; yeast - the entire amount according to the recipe.

Extracting yeast in such a mixture lasts from 1 to 3 hours, depending on the method of preparation of the dough, while the lifting force of the yeast decreases from 14 minutes to 8.

Result: The method is effective, but it involves a significant consumption of flour for activation, the use of scarce unfermented malt and does not exclude uneven and incomplete gelatinization of flour starch during the preparation of the brew. This negatively affects the accumulation of maltose in the mixture and therefore the activation effect. Flour consumption for activation is from 2.6 to 4.0 kg to the flour mass in the dough.
Experience in using malt and soy flour can be found in the topic Wheat bread with whole grain, rye on dough and custard malt

Mix for activation using fruit and vegetable powders.

Apple powder is used to activate yeast. Of the trace elements, it contains the largest amount of sodium, potassium, calcium and magnesium. The sodium ion is of particular importance. Its movement is associated with two mechanisms: passive entry into the cell from the environment and active movement from the cell into the environment using a "sodium pump". With the passive transfer of sodium, sugars and amino acids follow after it into the cell, even against the concentration and potential gradients for these substances. With the active transfer of sodium ion from the cell all the way, passive movement of the chlorine ion along the electrochemical gradient from the cell into the medium occurs, and at the same time the entry of the potassium ion into the cell.

Potassium activates numerous yeast cell enzymes (kinase, dehydrogenase), stimulates the fermentation of maltose and maltotriose; closely related to yeast reproduction and fermentation rate. Calcium stimulates cell proliferation, magnesium activates numerous enzymes (phosphokinases, decarboxylases), and stimulates the fermentation of maltose. The role of vitamins in the life of yeast is due to the fact that they are part of a variety of enzyme systems. Other biologically active substances have also been discovered. Therefore, apple powder is a biologically valuable additive that can be used to increase the fermentation activity of yeast.

When preparing nutrient mixtures, the powder is poured with water at a temperature of 35 ° C and mixed in order to ensure a more complete extraction of soluble substances. The yeast is kept at 33 - 35 ° C for 30 - 60 minutes. The lifting force of the yeast is improved from 12 (no activation) to 7 - 7.5 min. Increasing the dose of the powder is impractical, since this biological indicator of activated yeast improves slightly. As a result of this treatment, the α-glucosidic activity of yeast with the characteristic "bad" changes to the level of "good" and is 90 minutes. The presence of monosaccharides and sucrose in the powder of apple pomace ensures the restructuring of the cell from the respiratory to the fermentative type of vital activity.

The biological activity of the pressed yeast yeast cells is increased by keeping them in a nutrient mixture containing apple pomace powder and water. Powder in an amount of 0.35 - 0.375% by weight of flour in the dough is poured with water (8 - 10%) at a temperature of 34 - 35 ° C and vigorously stirred for 3 - 5 minutes. Pressed baker's yeast is added to the resulting mixture, stirred until a homogeneous suspension is formed and kept for 30-60 minutes at 33-34 ° C.

Result: The effect is to improve the fermentation activity of yeast cells by 1.5 - 1.8 times, to reduce flour consumption and improve the quality of bakery products.

In a dough mixed with yeast activated with apple powder (0.375%), the volume of CO2 released during the fermentation period increases by 58%, and during the proofing period of the blanks - by 55%. Physicochemical indicators of the quality of bread on activated yeast improve, namely: the porosity increases by 18.5%, the dimensional stability of hearth products improves by 22%.

Mix for activation using kvass wort concentrate.

Nutrient mixtures consisting of a concentrate of kvass wort, mineral salts and water are effective. To improve the fermentation activity of yeast, the salts KH2PO4, (NH4) HPO4 and NH4Cl are used as a mineral source.

Kvass wort concentrate is a semi-finished product enriched with sugars (maltose, glucose), amine nitrogen, microelements and vitamins. All substances are contained in doses that stimulate biochemical processes. This component of the nutrient mixture accelerates the restructuring of yeast cells from the respiratory to the fermentative type of vital activity.

To activate yeast cells, it is rational to add 0.02 - 0.025% KH2PO4 and 0.5% kvass wort concentrate to the nutrient mixture and keep them in this mixture for 45 - 60 minutes.

The introduction of mineral salts improves the process of gas formation during the fermentation of semi-finished products, however, the greatest effect is observed with the combined introduction of mineral salts and concentrate. The optimal dosage of (NH4) 2HPO4 is 0.035%, and NH4Cl is 0.025% to the mass of flour in the dough.

Air or oxygen saturation of the yeast suspension with nutrients is carried out in a special container to activate the yeast; the temperature of the compressed yeast suspension should be 30 - 32 ° C in winter and 18 - 20 ° C in summer.

Result: Use of activated yeast improves crumb porosity by 15%, increases the volume of finished products by 40%, improves flavor.

Due to the use of these salts together with the kvass wort concentrate plus aeration of the nutrient mixture during the activation period, an effective restructuring of the activity of the yeast cell occurs from the respiratory to the fermenting type.

To activate the yeast, it is also recommended to use by-products of the main production: ground tomato seeds, rice flour, curd whey, lactic acid starter cultures.

The mixture for activation can be replaced with a complex improver, since most of them contain an active amylolytic enzyme (α-amylase), soy flour and an oxidative enhancer. The dosage of the improver is selected in accordance with the manufacturer's recommendations.

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