Wort Filtration Process (2)

〖First wort filtration〗

The filtration time of the first wort is generally about 60min. If the advanced new filter system is adopted, combined with good tillage operation, the filter time can be reduced to less than 60min.

When the reflux wort is clear and the reflux is over, open the valve that enters the boiling pot or the wort temporary storage tank to allow the wort to enter. In order to maintain the looseness 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, it should be controlled at 1/4-1/3 opening, and then gradually open the valve according to the wort brightness and filtration time requirements.

During the filtration period, the plowing machine can be activated to loosen the filtration layer and improve the filtration speed. However, the rotation speed of the tiller should not be too fast, 1/5-1/3r/min is appropriate. The height of the tiller should be from top to bottom, but the minimum distance of the final filter plate is about 3cm, which should not be too low to avoid damage to the filter plate by the tiller.

When filtering for 15-20min (or according to the specific situation), measure the first wort concentration. In order to ensure the wort concentration after filtration, the first wort concentration must be about 40% higher than the stereotyped wort concentration. For example, to produce beer at 12°P, the first wort concentration must be around 16°P.

Factors Affecting First Wort Filtration

• Wort viscosity

The higher the temperature, the lower the viscosity of the wort and the faster the filtration speed.

• Grain resistance

Filtration begins with the least resistance and becomes larger and larger as the filtration process progresses.

• Filter operation

Filtration operations are not static and must be adjusted as the trough resistance changes. Moreover, there are many factors that affect wort filtration, such as malt quality, saccharification method, composition of pulverization, filter sieve plate load and filter plate structure, initial filtration operation, etc. The filtration operation should be flexibly adjusted according to some practical factors.

• Malt quality

The malt of good quality has relatively few upper and lower grains in the filter layer. The research shows that under the same pressure, in the first wort filtration stage, the lower grains and the spent grains play a leading role; in the washing stage, the upper grains play a leading role. It can be seen that, in order to speed up the filtration rate of the first wort, it is necessary to reduce the generation of lower particles.

Using good quality malt, the obtained wort has low viscosity, relatively loose spent grains, fast filtration speed and short filtration time. Usually, the lower the wort viscosity, the shorter the filtration time. But there are exceptions, such as strong stirring during mashing, and the husk in the mash is broken. Even if the viscosity of the wort is low, the filtration time is still long.

• Dosage of excipients

Particles such as protein, hemicellulose, starch grains and lipids that are not broken down during mashing will affect the filtration speed of wort. The amount is related to the degree of dissolution of the malt and the type and amount of added grains. Sometimes adding β-glucanase to saccharification is a measure that is beneficial to filtration, which can improve filtration.

• Crushing method

The filtration speed of wet pulverization is significantly higher than that of dry pulverization and humidification pulverization.

The thickness of the dried grains layer is about 35cm, the wet grinding is about 40cm, and the wet grinding is about 55cm. It can be seen that when the wheat husks in the crushed materials are well preserved, and the volume of the wheat husks is large, the formed wheat grains layer is relatively thick, and the feeding amount per unit sieve plate area can also be increased from 200g/m2 to 225kg/m2 Even 300kg/m2.

Inspection of the first wort

The quality of the first wort is very important, it is a sign to check the quality of the malt and the results of the mashing operation. Among them, the color, brightness, smell, taste and iodine reaction of wort are easy to check.

The color of the first wort is checked at each filtration, from which it is possible to predict the color of the blended, hot and cold wort and finished beer.

It is more important to check the clarity of the wort at the different stages of filtration. Generally, after 10 minutes of filtration, the clarity should reach a satisfactory level. When the wort layer is tight, although the clarity of the filtered wort is improved, it is obviously difficult to filter. However, when plowing grains, it has a certain impact on the clarity of the wort.

It is necessary to measure the quantity and concentration of the first wort in time, so as to calculate the yield of the first wort and the addition amount of the dregs water. Under normal circumstances, when a small atmospheric filter tank is used to produce wort, the first wort yield is generally about 50%.

The first wort yield is calculated according to the following formula:

The first wort yield ≈ the first wort volume (hL) × 0.98 × the first wort concentration (°P)/feeding amount (100kg)

The coefficient used to calculate the amount of the first wort is different from that of the hot wort, because the temperature of the first wort is only 70℃ and the shrinkage is small, so the correction coefficient is 0.98.

• Sink

When the first wort filtration is close to the end, there are still residual extracts in the spent grains. In order to improve economic efficiency, it should be thoroughly washed out. This process is called spent grain washing. The water used for washing grains is called grain washing water, and the washed wort is called second wort. The water containing the extract that flows out at the end of the washing is called the residual liquid.

〖Washing method〗

Under normal circumstances, washing the bad is carried out in two or three times. The water consumption of the first washing of the wort is about 30%, and the first wort is discharged from the wort first; the water of the second washing of the wort is about 50%, so that the content of the extract can be smoothly reduced; the water of the third washing tank is about 20%, and further The extract from the spent grains is washed out.

Washing waste with water

Although the higher the water temperature for washing the grains, the faster and more thorough the grain washing will be. However, there are also requirements. The water temperature must be controlled within the saccharification temperature range, generally 76°C~78°C, and the highest should not exceed 80°C; if the temperature is too low, the residual sugar is not easy to be washed, and it is easy to contaminate bacteria; if the temperature is too high, the It will affect the filtration of wort, enhance the oxidation of wort, deepen the color of wort, and affect the taste and flavor of future beer.

The amount of washed wort depends on the quantity and concentration of the first wort, the concentration of the full pot of wort and the evaporation of the boiling pot. For light-colored beer, generally saccharified with dilute mash, the water consumption for washing the tank is less; for the production of dark-colored beer, generally thick mashed and saccharified, the amount of water used for washing the dregs should be increased accordingly.

〖Disposal spent grains〗

When the concentration of the washed grains wort reaches the specified value of the process, stop washing the grains. Open the drain valve to dry the residual liquid in the grains, then open the windshield, open the grains discharge port, start the grain tiller and drop the grains scraper to discharge grains. After the waste disposal is completed, clean the cultivator and the sieve plate, and set aside.

The waste removal should be carried out slowly from top to bottom, so as not to cause the pipeline blockage due to the rapid discharge of the waste; do not plough the waste too deeply, so as not to cause the deformation of the tiller; the lifting and lowering of the tiller should not exceed the upper and lower limit marks, so as not to damage the sieve plate by the tiller. .

The grains discharged after filtration has a water content of 70% to 80%. 100~130kg of wet wheat grains can be obtained per 100kg of feeding amount.

Wheat grains contain a small amount of sugar and a large amount of protein, which are rich in nutrients and easily rancid. Therefore, effective processing must be carried out immediately.