Milking yeast (is not a fantasy)

[Alex_Sor]

Milking yeast is not a fantasy.

Introduction.

Classical fermentation (wort fermentation process) is a familiar process. Bacteria (yeast fungi) eat up sugar and release carbon dioxide and ethyl alcohol in the process. Everything is very good, but yeast eats sugar and defecates with alcohol at the same time 🙂 And then we boil the mixture together with the bacteria, kill them, and release alcohol and with it the by-products of the yeast's vital activity, including "heads", "tails" and various toxic substances.

What if you don't kill the yeast? We don't kill a cow when we want milk? We don't kill bees when we want honey?

This idea has occurred to people more than once, and it was even tested. The results were very interesting and positive. But how to take alcohol away from yeast without killing it? It's very simple - you need to create a vacuum! High vacuum so that the alcohol boils at 20-28 degrees Celsius, while the yeast does not die, and carbon dioxide and alcohol, as well as light (aromatic) impurities (heads, ethers) are removed from the mixture.

Experiments have shown that the use of vacuuming fermenting wort leads to an increase in the degree of fermentation of sugars. Increase in the total degree of fermentation of sugars by an average of 10%. As a result of the removal of yeast metabolites from the mixture, the alcohol yield increases in terms of fermented sugars. Thus, under vacuum, the alcohol yield is 74% of the theoretical, while at atmospheric pressure it reaches only 50%.

Alcohol quality problem.

In recent years, the industrial production of edible ethyl alcohol has been characterized by a significant increase in the requirements for physicochemical and organic the leptic quality of alcohol. Much attention is paid to the modernization of rectification plants, which provide deep purification of alcohol from impurities formed during technological processes.

A further increase in the physicochemical and organoleptic quality of alcohol can be achieved on the basis of technological solutions aimed at preventing or significantly reducing the formation of impurities during its production. As you know, under anaerobic conditions, the yeast cell Saccaromyces cerevisiae receives energy for reproduction and growth by converting glucose into ethyl alcohol. Besides actually plastic metabolism, part of this energy is spent in the so-called maintenance metabolism, associated, among other things, with the work of active transport systems against the gradient of the osmotic pressure of the environment. Since alcohol is the strongest factor in osmotic pressure, its accumulation during fermentation gradually leads to energy starvation of cells, cessation of growth and biosynthesis of alcohol, and their death. The process of suppression of vital activity and the death of yeast begins to manifest itself noticeably even when the alcohol content in the medium is 6-8% vol. and is accompanied by a number of metabolic changes and, accordingly, a sharp an increase in the amount of polluting metabolites. In this regard, when selecting industrial strains-producers of ethyl alcohol, one of the most important features is their osmotolerance. (i.e. the ability not to die at alcohol concentrations of 12-15%). Along with the impurities intensively formed by alcoholic yeast at the end of the fermentation period, impurities are also formed by the polluting microflora.

For example, isopropanol is one of the impurities that are most difficult to separate by brago rectification, it is formed by clostridia that get into the wort with soil residues and grain weed. Increasing the level nya aseptic processes of fermentation and yeast generation also leads to a decrease in the content of impurities in alcohol and an increase in its organoleptic quality. The mash column, in which the mash is boiled under atmospheric pressure, is also a powerful generator of impurities. The content of some impurities in the brew distillate, for example, acetaldehyde, increases several times in relation to the original brew. New growths that were not contained in the brew are also added. The use of a vacuum in the distillation of the mash is known to significantly reduce the formation of impurities at this stage.

When obtaining alcohol from grain, practically only starch, which makes up 52-54% of dry matter of grain, is used for the biosynthesis of alcohol. The rest is displayed with bard. The dry matter of stillage contains about 28% of crude protein, in which up to 40% of bypass proteins are especially valuable for cattle. Therefore, the grain stillage of distilleries is It is, in principle, a very valuable feed resource for animals.

Studies have established that the course of fermentation in a vacuum is characterized by a number of distinctive features that make this technology very attractive, especially for the production of high-quality alcohol:

1) Under vacuum conditions, alcohol is distilled directly in the fermentation tank at the fermentation temperature, and it is removed from the liquid phase immediately by to the extent of its formation. Thus, fermentation takes place at practically zero alcohol concentration in the brew.

2) The rate of alcohol formation (hence, the productivity of the equipment) increases 2-3 times.

3) The viability of the yeast and its activity is maintained at the original level, throughout the entire fermentation cycle.

3) The yield of alcohol per ton of starch remains within the limits of not lower than the established norms. At the same time, the accumulation of yeast biomass increases in times.

4) It becomes possible to increase the mixing module up to a 1:1 level.

5) In the fermentation tank, when working with such hydromodules, there is practically no foreign microflora. There are no impurities typical for polluting microflora, for example isopropanol.

6) At the exit from the fermentation tank, the concentration of alcoholic distillate is 35%, which makes it possible to send it directly to the epuration, excluding the beer column from the rectification unit.

7) At the end of the fermentation cycle, due to the evaporation of water, the dry matter content in the liquid phase of the fermentation tank increases to 26-30%. This creamy, fluid-retaining liquid containing 32-36% crude protein is essentially a concentrated vinasse, ready for final drying.

 

I will not bore you with details 🙂 I will give just one tablet, which contains data on the chemical analysis of various components during the "milking of bacteria" in comparison with conventional fermentation and classical distillation.

(Control is classic fermentation)