Brewery Setup Blog

Wort Lauter Tun Technology（二）

The wort lauter tun process mainly includes seven processes of topping hot water, waking up, standing, turbid wort reflux, first wort reflux, sparging and spent grain discharge.

(1) First wort reflux

The filtration time of the first wort is generally 75~105min. If the advanced new filter system is adopted, coupled with good tillage operation, the filter time can be reduced to less than 60 minutes. When the reflux wort is clear, the reflux ends, and the valve that enters the boiling pot or temporary wort storage tank is opened to allow the wort to enter. In order to maintain the porosity of the spent grains layer, the filter pressure difference should be kept as small as possible. When the filter valve is opened, it should not be too fast. At the beginning, the opening is controlled at 1/4~1/3, and then the valve is gradually opened according to the clarity of the wort.

During the filtration period, the cultivator can be used to plow the grains to loosen the filter layer and increase the filtration speed. However, the rotation speed of the cultivating knife should be slow, preferably 1/5~1/3r/min. The height of the cultivator can be adjusted up and down, but the minimum distance from the filter plate is 3~5cm. Do not put it too low, so as not to scratch the filter plate with the tiller. Modern filter tanks are often equipped with differential pressure gauges to automatically adjust the speed and depth of tiller.

When the first wort is filtered, amylase can be added to the boiling pot according to the process requirements to further liquefy a small amount of high-molecular dextrin in the wort, so that all of it can be converted into colorless dextrin and sugar, and the utilization rate of raw materials can be improved.

When filtering for 25 to 30 minutes, measure the concentration of the first wort to determine the amount of washing water added. In order to ensure the concentration of the wort after filtration, the concentration of the first wort must be higher than the concentration of the wort to be fermented, which is about 40% to 80% higher. For example, to produce beer with 12°P, the first wort concentration must be 16~20°P. 

(2) Sparging

At the end of the first wort filtration, there are still extracts remaining in the grains. In order to improve economic benefits, it should be washed out thoroughly. This process is called grain washing. The water used for washing the grains is called the water for washing the grains, and the extracted extract is called the second wort. The water containing extracts flowing out at the end of the washing is called the washing raffinate.

A. Washing method

Generally, the washing of grains is carried out in two or three times. The water consumption for the first washing of grains is less (about 20%), and the first wort is discharged from the grains first; the water for the second washing of grains is about 50%, and the content of extracts decreases smoothly; the water for the third washing of grains is about 30%. %, to further wash out the extract from the wheat grains.

B. Wash water

The higher the temperature of the washing water, the faster and more thorough the washing of the grains. However, the water temperature must be controlled within the saccharification temperature range, generally 76°C to 78°C, and the highest should not exceed 80°C. The amount of washing water depends on the quantity and concentration of the first wort and the concentration of wort in the boiling pot, which has a great influence on the yield of wort. In the production of light-colored beer, the concentration of the mash is relatively thin, and the water consumption for washing the grains is less; in the production of dark-colored beer, the saccharification liquid is thicker, and the water consumption for washing the grains should be increased accordingly.

C. Washing process

The whole grain washing process usually lasts 90-120 minutes, and the modern lauter tank is equipped with a well-performing grain cultivator, which can speed up the filtration. When the wheat grains are just exposed, the filtration of the first wort should be stopped and the washing water should be added according to the process requirements. The waste washing water submerges the wheat grains, and the extract in the wheat grains is washed out before washing or in the grains, and the cultivator should be started. Whether the cultivator starts or not depends mainly on the filtration performance of the wheat grains. The quality of the tillage work determines to a certain extent the length of the filtration time and the clarity of the wort. When the specified mixed wort concentration is reached, the washing of grains can be stopped. The concentration of mixed wort is generally controlled at 1.0~1.5°P lower than the final wort concentration (for example, 11°P beer is generally controlled at 9.4~9.6°P), and excessive washing of grains should not be allowed. Otherwise, harmful substances such as tannin, wheat husk bitterness and silicate in the wheat husk will dissolve and enter the wort, which will damage the quality of beer.

(3) Spent grain discharge

When the concentration of the washed wort reaches the specified value of the process, stop washing the grains. Open the drain valve and empty the residual liquid in the wheat grains. Then open the windshield, open the outlet of wheat grains, start the tiller and drop the waste scraper to discharge waste. After the waste is discharged, the tiller and the sieve plate are cleaned for later use.

The dross discharge should be carried out slowly from top to bottom, so as to avoid pipe blockage caused by the dregs coming out too quickly; do not plow the dregs too deeply, so as not to cause deformation of the tiller blade; do not lift the dregs machine beyond the upper and lower limit marks to prevent the tiller blade from scraping the sieve plate. After the residual liquid from washing is finished, adjust the cultivator knife horizontally to discharge the grains.

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