Lesson 6 - Process Aids and Additions

CSS or controlled stabilisation system is a proprietary solution for chill proofing. It consists of modular vessels containing a cross-linked agarose (a polysaccharide) bead bed of 100-300 μm bead diameter.

The CSS stabilisation system targets the adsorption of polyphenols and ensures gentle and effective beer stabilisation. The stabilising agent always remains within the system. This is unlike PVPP, where a small percentage is lost each time it is regenerated. Polyphenols are adsorbed by the agarose and are only removed from it again during regeneration. The agarose does not enter the beer and it does not adversely affect the other beer quality components. Therefore, the sensory characteristics, foam stability, beer colour, and the bitterness units of the beer will not change.

After primary filtration, a proportion of the filtered beer (you must determine the actual amount for your particular beer) passes through the agarose bed and polyphenols are adsorbed onto the beads. The proportion increases as the beads become saturated, until primary filtration ends. The agarose bed is regenerated with caustic soda when the primary filter is being re-prepared for a new filtration run. This regeneration process using caustic removes accumulated organic material such as polyphenols from the agarose beads. This in turn exposes the surface for further adsorption. The CSS system is considered to be a cost-effective alternative to a regenerable PVPP plant.

Figure: Principles of CSS treatment