The production of a beer (Lager, Ale, Porter, Stout) benefits from filtration as the method for controlling the flavour, stability, appearance and shelf life of the packaged product. The areas where filtration is used fall into 4 categories:
- Incoming Water
- Rough Filtration
- Trap Filtration
- Sterile Filtration
Different brews use different processes, meaning one, two or all three of these filtration stages may be required dependent upon the Brewer’s desires for the final product. Challenges to the brew may be in the form of haze from polyphenols, appropriate yeast levels, the presence of spoilage organisms, the desired colour, flavour, brightness of appearance and their customer’s requirements for shelf life. These challenges can be overcome using the solutions that Sterner recommends.
- Haze from polyphenols
- Appropriate yeast levels
- The presence of spoilage organisms
- The desired colour & flavour
- The brightness of appearence
- Your customer's requirements for shelf life
Rough filtration is the removal of bulk solids such as grist and bulk yeasts. Process filtration often uses bags for this purpose as bags allow a high flow rate, remove a large volume of solids and are quick and easy to change out, making them economic to use. Bags are available with options of nylon mesh, polypropylene and polyester with traditional single-layer, extended life double-layer and high-efficiency multi-layer with Micro fibres incorporated for fine sediment removal. Bag filtration is commonly used to remove bulk solids, e.g. grist and bulk yeasts.
Incoming Water for Brewing Liquor
Incoming mains or borehole water would typically be filtered via an RO system for brewing liquor production and boiler feed. Microbreweries and craft brewers will often filter the incoming water with carbon cartridges to remove chlorine and other chemicals, which could affect the taste of the beer.
During the filling of sterile beer kegs and bottles, the beer is typically filtered to 0.45µm either with one pleated cartridge or a two / three stage system (typically 5µm > 1µm > 0.45µm). This is for clarification and to prevent microorganisms spoiling the final packaged product.
Beer is stored in sterile tanks, which have 0.1µm or 0.2µm air vent filtration to prevent ingress of bacterial contamination.