Craft beer wort production (2)

The main process of beer production is fermentation, which converts the sugar contained in the wort into ethanol and carbon dioxide. In order to achieve the preconditions for fermentation, the water-insoluble components in the malt must first be converted into water-soluble components, especially fermentable sugars. The conversion and dissolution of these water-insoluble components is the purpose of wort preparation and also The basis for the fermentation of wort in the main leaven and after leaven. The preparation process of wort includes: crushing of raw materials, saccharification of raw materials, filtration of wort, boiling of wort with hops, wort treatment (clarification, cooling, oxygenation) and other processes. The following describes the preparation of wort through several aspects.

Wort filtration

At the end of the saccharification process, the decomposition and extraction of high-molecular substances in the malt have been basically completed, and the wort must be separated from the grains in the shortest possible time, that is, the water-soluble extract and the residual husk, high-molecular protein , cellulose, fat, etc., the separation process is called wort filtration.

Wort filtration methods can be roughly divided into three types. The first is the filter tank method, the second is the rapid seepage tank method, and the third is the filter press method. The filter press method includes traditional filter presses, bag filter presses, membrane filter presses and chamber filter presses. points.

The commonly used filtration method for fine brewing is the lauter tank method. The principle is to settle and accumulate the insoluble components in the saccharification mash on the sieve plate through gravity filtration to form a natural filtration layer (called the spent grain layer), and the wort relies on gravity to pass through the malt. Wort layer is obtained.

The effective volume of the filter tank is about 75% to 80% of the total volume, and the thickness of the bad layer is the main factor of the filtration resistance, which is determined according to the different methods of malt crushing. Generally due to follow:

The thickness of the bad layer of malt dry crushing is 25-40cm.

The thickness of the bad layer of malt wet pulverization is 40-50cm.

When the lauter tank method is used for filtration, the improvement of the filtration speed is the key to improve the filtration efficiency, and the filtration speed is mainly affected by the viscosity of the wort, the thickness of the filter layer and the filtration pressure. The greater the viscosity of the wort, the slower the filtration; the greater the thickness of the filter layer, the slower the filtration speed, but too thin thickness will reduce the transparency of the wort; the filtration pressure is proportional to the filtration speed (the filtration pressure refers to the liquid level above the spent grains layer) The difference between the pressure and the pressure under the sieve plate), the increase of the pressure difference can speed up the filtration, but it is easy to compact the layer of wheat grains and cause compaction, which reduces the filtration rate.

Wort boil

The clear wort obtained by filtering the mash is boiled, during which hops are added. Wort boiling is an extremely important step in saccharification, which has an extremely important impact on the process control of the next fermentation process until the production of high-quality products. The quality of the boiling process directly affects the improvement of flavor, the formation of coagulum, stability issues and the control of wort concentration.

The greater the boiling intensity, the more conducive to the denaturation and flocculation of protein, and the more clear and transparent wort with less nitrogen content can be obtained. Generally, the boiling intensity should be controlled at 8% to 12%.

Short boiling time is not conducive to the coagulation of protein and the stability of beer. Prolonging the boiling time reasonably is beneficial to protein coagulation and the formation of reduced substances. But too long boiling time will reduce the quality of wort. Under normal circumstances, the boiling time is controlled within 90 minutes.

PHE

Wort treatment

After the wort is boiled, it cannot enter the fermentation immediately, and a series of treatments are required, including: thermal coagulation separation, condensation solidification separation, cooling and oxygenation of the wort and a series of treatments. Due to the different fermentation technology and quality requirements of finished beer, the processing methods are also quite different. The main difference is whether or not the condensate separates.

The requirements for wort treatment in beer brewing are:

(1) The cold and hot suspicious solids that may cause abiotic turbidity in beer should be separated as much as possible.

(2) When the temperature of wort is high, it is necessary to reduce the contact with air as much as possible to prevent oxidation. After the wort is cooled, before fermentation, an appropriate amount of oxygen must be supplemented for the respiration of the yeast in the early stage of fermentation.

(3) In each process of wort treatment, the pollution of harmful microorganisms should be strictly prevented.