After longer periods of storage, filtered beer loses its clarity and brilliance, especially when it is cooled, to the point that haze or a sediment layer forms in the beer. In order to eliminate sensitivity to cold and to avoid undesirable haze or turbidity, beer is often treated with clarifying agents, which allow beer to remain free of haze for months longer than it would without such treatment. Because it is valuable to gain some insight into the stability of packaged beer as early as possible, methods of analysis have been developed that provide information immediately after the packaging process regarding the propensity of a beer to form haze.
The expected haze-free shelf life of beer is best determined by employing so-called forced aging methods.
Suitable for all beers
Forced aging is the most practical means for determining the duration of shelf life and the potential for haze formation in beer. In the forced aging test, an appropriate number of bottles (at least five) are subjected alternately to temperatures of either 40 °C (untreated beer) or 60 °C (stabilized beer) and 0 °C until the turbidity increases by > 2 EBC formazin units as a result of forced aging.
By multiplying the value determined in performing the test, expressed in ‘days of shelf life at 40 °C or 60 °C’, by a factor specific to beer (conversion factor), it is possible to predict how long a beer will remain free of turbidity or haze in the package.