In addition to clarification (i.e., removing yeast), beer must display physical stability with respect to haze. Colloidal instability in beer is caused mainly by interactions between polypeptides and polyphenols. Amino acids make up polypeptides which, in turn, make up proteins. Polypeptides and polyphenols combine to produce visible haze that reduces a product's physical shelf life. Reducing the levels of one or both of the precursors using suitable stabilizing treatments will extend physical stability.
Polypeptides responsible for haze formation originate mainly from barley. Polyphenols in beer originate from barley and hops. Polyphenols are mostly lost throughout the brewing process, particularly during mashing, boiling, wort cooling, and maturation.
To remove polypeptides or polyphenols and to improve its physical stability, a number of methods are employed for reducing chill haze. This procedure is often referred to as "chillproofing."
Over the years a number of chillproofing agents have been used to enhance beer haze stability (i.e., reduction of beer proteins and/or polyphenols). Each agent has its pros and cons, and many are used in combination, to suit the brewers own requirements and plant constraints.
Brewhouse Procedures Used for Stabilizing Beer
It should be noted that neither, stabilization or clarification or for that matter filtration are end-all measures for correcting mistakes made in the production process. Therefore, from the very beginning, it is necessary to perform stringent quality control paying attention from the selection of raw materials all the way through to conditioning, filtration, and packaging. Some of the techniques that a brewer can employ to achieve colloidal stability are as follows:
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