Fermentation or fermentation is the main process in the preparation of the most popular foamy drink (at home or at production facilities - no difference). During beer fermentation, sugars that are in bulk are converted by microorganisms into alcohols, together with carbon dioxide and other elements present in the final product in small doses. Therefore, all home brewers need to know how this procedure occurs. Our today's article will tell about this. We hope that the information comes in handy!
Brewer's yeast - who are they?
Beer fermentation is provided by brewer's yeast. Some of their varieties can function at low temperatures (0-15 degrees Celsius), being at the bottom of the tank. They are called grassroots or camp.
Another main variety, more ancient and popular over the centuries in Europe - ale or horse. These microorganisms "work" in heat (the fermentation temperature of beer is 15-27 degrees Celsius). And in the process "hang out" in the upper layers of the wort. But at the end of the procedure, they also fall to the bottom of the tank, and the fermentation rate drops to a large extent.
How to handle yeast
First of all, they are living organisms, therefore, they need to be handled in a delicate way, not exposed to: sudden changes in temperature, change of habitat, increase in pressure, and ethyl content. Indeed, under negative conditions, they can slow down the fermentation of beer, even die. Yeast is usually “fermented” ahead of time in order to quickly begin to perform its direct functions, along with the reduced risk of wort infection.
Therefore, experts recommend that beginners in beer business take a disinfected container half an hour before the introduction of microorganisms into the wort, pour half a glass of water there (boiled, at a temperature of thirty degrees), add a little sugar and pour out dry yeast. Then mix gently, but do not shake, and cover with a kitchen towel.
The introduction of microorganisms in the wort
When the wort is fully prepared for the introduction of microorganisms, you need to once again control the temperature. It is best to introduce yeast in portions so that they feel perfect. Then, gently, not strongly, mix the entire mass in the container.
To ensure the onset of beer fermentation, the temperature scale of the total mass with the introduction of top-type microorganisms should be 23-27 degrees (the dose of the product, as a rule, is indicated on the packaging from the manufacturer and varies in the region of 10 grams per 20 liters of beer). And when using the grassroots - it is in the region of 17-23, gradually decreasing to 9-15 (dosage of 20-50 grams per 20 liters).
- Then we close the dishes tightly, install a water lock, pouring half the liquid into it (boiled water with the addition of available disinfectants). We place the dishes on an elevation so that it is more convenient to pour the final product into bottles or barrels.
- We monitor so that during fermentation, the ambient temperature does not change much. You should not mix, shake, worrying wort.
- The start of fermentation varies - from two hours to a day, it depends on the temperature of the wort, on the general condition and health of microorganisms. Optimum - 20 degrees, since at lower temperatures the process proceeds rather slowly and reaches two to three weeks. And at 25, for example, the first fermentation of beer will be carried out too violently, for about three to five days (at the same time, the drink may have an undesirable aroma and become cloudy, since the yeast is suspended for a long time), and then the beer for a long time will be clarified.
At the finish of the process, there is no foam on the surfaces, and the drink has an unsweetened taste. In this case, microorganisms settle to the bottom of the tank, and beer is clarified. If bottled beer is bottled, then a yeast precipitate forms, which gives the drink an undesirable (so-called sweet) flavor, and if the bottle is opened, the microorganisms rush up, shaking the drink. But you don’t need to delay with transfusion, as there will not be enough yeast in the “crystal” beer, and during the carbonization (secondary fermentation), other forms of microorganisms begin to consume added sugar.
Top fermented beer
Modern mankind knows several methods for making a foamy drink. One of them is horse fermentation. It is produced using the appropriate yeast (Saccharomyces cerevisiae). This process is more ancient in comparison with the grassroots counterpart. This is due to the rather late invention of refrigerators. And until that moment, only in a limited number of breweries did the conditions for a “cold”, that is, bottom fermentation of the drink, appear. Therefore, according to the historians of brewing, top fermentation at temperatures up to 24 degrees Celsius for a long time was predominant, for example, in the Middle Ages and much later. It is characteristic that the top yeast does not divide for a long time after budding and form branched colonies. They form bubbles of carbon dioxide, pushing the accumulation of microorganisms up. Hence another name - ascending fermentation. When mounted, higher alcohols and esters are formed in large quantities, and this cannot but affect the aroma and taste of the final product.
What varieties can be attributed to top fermentation? First of all, it is English ale, Belgian lambic, German altbier and wheat beer. Now interest in the production of this kind of beer in the world has grown sharply, which is associated with an increase in the number and capacity of craft mini-breweries.
Bottom Fermented Beer
Another production method uses saccharomyces pastorianus yeast and is called bottom fermentation. It is the most modern, widespread everywhere in comparison with the top. And a drink prepared by this method can be stored for a long time without pasteurization (by the way, beer prepared by top fermentation is stored for only a few months). The risks of wort infection are also reduced, since the process itself occurs at a much lower temperature (about 10 degrees).
The difference between bottom fermentation: in the process, the maximum concentration of microorganisms is at the bottom of the tank (for the top, yeast accumulation at the top of the wort is typical). After processing carbohydrates, grassroots yeast also precipitates (some of them die, and some hibernate). Grassroots beer is called lager.
In the second round
Secondary fermentation of beer is considered by experts to be extremely necessary, since as a result of the main one, along with ethyl, a lot of by-products are produced that are quite harmful to humans. And they can affect the taste and smell of drinks. During secondary fermentation, a certain amount of sugar is added (carbonization), microorganisms are activated, and harmful products are transformed, ceasing to have a direct effect on taste. This process consists in the maturation of the final product, the main conditions for it are the preservation of yeast activity.