Some basic rules for hygienic design
Hygienic design can go very far. As with all guidelines, it is an art to maintain the balance between the pursuit of the most appropriate hygienic designed installation and its functionality. By taking into account some basic rules, the cleanability of your process line will already significantly improve without significant costs.
Select materials in function of ingredients and chemicals
The first step to a hygienically designed process line is the right material. Stainless steel is the material of choice for pipes, tanks and other process components. But there are so many different types of stainless steel: which type best fits your application? And what about the seals that are in direct contact with the food in your process line? The choice of the most suitable materials is dependent on three basic elements:
- The processed ingredients, such as chocolate, eggs, enhancers, and so on
- The used cleaning agents and disinfectants
- The temperature
Take care of the finishing grade of all contact surfaces
A process line may be made out of the most suitable materials, but if there are small pits, inclusions or cracks in the surface, problems will arise. If surface is too rough, good cleaning will be hard to reach and bacteria will have the opportunity to attach themselves to the surface. Therefore, it is recommended that the surface that comes in contact with the food product has a degree of roughness ( Ra ) of less than 0.8 micrometers.
Provide hygienic connections without sharp transitions or splits
Avoid metal-to-metal joints, crevices, blind corners and edges. Welded connections are absolute priority. If this is not possible, metal-to-metal connections should contain a rubber gasket for a complete closure.
Avoid threaded connections where possible , because the thread is a potential breeding ground for bacteria. In practice, bolts and nuts are often used to fasten for example agitators. If such connection are necessary, do not forget the right rubber seal.
Read the full article (published in the newsletter of STW Food Gate ).