Mash tun is mainly used for the decomposition of malt starch and protein, and the temperature of the mash needs to be gradually raised to keep the mash at a certain temperature for starch saccharification. Mash tun needs to have heating and stirring functions.
Among them, the design of the size of the stirrer is very important. Its rotating speed must be compatible with the diameter of the pot body, and the linear speed must not exceed 3m/s, otherwise it will generate shear force on the mash and change the content of the mash. The basic requirement for the mash stirring device is to make the solid particles for material mixing be suspended and evenly distributed in the liquid, so as to avoid local overheating, scorch, and affect the quality of wort and beer.



The Stirring Paddle is long, wide and symmetrical
 
We know that when heat is transferred to the heating medium by convection, it must be ensured that local overheating will not be caused, so as to keep the heat conduction constant. In addition, the original energy should be fully utilized to shorten the contact time. Therefore, the use of symmetrical paddles that are long and wide (paddle diameter is 0.85~0.90 of the tank body), with the outer edges in the opposite direction, is conducive to this effect. On the one hand, convection can be used to increase heat transfer and reduce the possibility of mash scorching; on the other hand, the use of wide blades can run at lower speeds, reducing the mechanical load caused by shear forces. Previously, the maximum linear velocity could reach 3m/s, but the newly designed blade linear velocity can be reduced to less than 1m/s.
 
Stirring Paddle is angled and has holes
 
Adequate contact is required for full action of enzymes and substrates in the mash. If the Stirring Paddle has the correct inclination angle, it can make the mash form a rotating motion in the pot, and form a rolling mixed mash (full movement and rolling cycle from the inside to the outside and from the bottom to the top), thereby avoiding the heavier in the mash Parts gather in the middle, which can ensure the uniform temperature in the pot (the temperature difference between the upper and lower sides is less than 0.3°C), and promote the full contact between the enzyme and the mash. In addition, the new paddle opening can also reduce shear force and reduce oxygen intake.
 
Stirring device can be lifted
 
When the mash is heating up, the stirring paddle should be at a lower position close to the heating surface, and the heat conduction can be enhanced by generating as strong convection as possible on the heating surface, and at the same time, local overheating or sticking can be avoided. In contrast, during the rest phase, it is advantageous to have the stirring paddle in a higher position. Because the "pumping effect" at this time is obviously better than that at the lower position, and at the lower position, there is only a small suction space.
 
The stirring device adopts frequency conversion adjustment, which greatly enhances the flexibility
 
In actual production, the change of non-water-soluble substances (NHF) is often used as an important parameter to measure the shear force, and the absolute content of non-water-soluble substances depends to a large extent on the structure of the stirring device. The higher the content of non-water-soluble substances (NHF), the greater the shear force on the mash, and the faster the stirring speed at this time. Therefore, in the mashing process, we must reduce the stirring speed as much as possible to reduce the content of non-water-soluble substances (NHF). Therefore, our stirring device adopts frequency conversion adjustment, and the stirring speed can be flexibly adjusted according to the requirements of the mashing process, so as to adapt to the mashing step, so as to control the convection speed of the mash and avoid excessive shearing force. Especially in high-concentration mashing, the new stirring device can show its unparalleled advantages.
 
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Edited by Cassie
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