Stainless steel is the preferred material for most brewing equipment due to its durability, resistance to corrosion, and ease of cleaning. Common stainless-steel materials used in brewing and fermentation equipment include SUS304, SUS316, SUS304L, and SUS316L.
However, aside from selecting high-quality stainless steel, an often-overlooked factor in equipment selection is the interior surface polish of the tank.
Let's start with a brief explanation: the irregularities in the surface polish process are referred to as "roughness depth", and this depth can be minimized through appropriate surface polish methods. The most significant measure of surface finish quality is the "average roughness" Ra, which is directly linked to the roughness depth.
The inner surface should be as smooth as possible, with no visible gaps under a microscope. To ensure optimal quality, the surface polish should achieve an average roughness of Ra <1.6μm, preferably below 0.8μm.
Particular attention is needed at the tank's top and conical outlet, where the surface must be smooth to prevent the growth of microorganisms. The size of yeast ranges from 6 to 10μm, making it unable to adhere to the top tank surface after mixing. In comparison, bacteria are much smaller, measuring between 0.7 and 4μm. It’s worth noting that bacteria and smaller wild yeasts can inhabit these tiny pores, causing contamination over time. Therefore, even the welds require meticulous polishing to inhibit microbial growth.
Through grinding and polishing, the Ra value of the stainless-steel surface can be reduced to 0.3-0.6μm, but the processing cost will increase accordingly. Tiantai's brewing and fermentation equipment can be polished to an impressive 0.3-0.4μm without any inaccessible dead corners, ensuring equipment hygiene and safety during use.
Furthermore, it is essential to regularly inspect the microbial condition of the tank's contents over time and after long-term usage. Detecting microorganisms during the production implementing appropriate cleaning and sterilization measures promptly is crucial to avoid quality issues that might affect the finished beer.
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