Prediction of colloidal stability of highly stabilised beers by modified Chapon's tannoid content test
Abstrakt
The tannoid content test, introduced by Chapon, is accepted as a recommended MEBAK analytical method for the detection of haze-forming polyphenols in beer and other intermediates. Under certain conditions, the results can be used directly for predicting the colloidal stability of beer.
Its disadvantage is that it does not provide detectable results for beers stabilized by high doses of polyvinylpolypyrrolidone (PVPP). A test modification is proposed that increases the test sensitivity and gives non-zero results, even for highly stabilized samples that are not measurable by the standard test.
The modification is based on adding saturated ammonium sulphate solution (SASS) to the sample to reach 9% saturation (0.5 mL of SASS to 5 mL sample volume) before the actual test performance. The results of the modified test can simply be converted to results obtained by the standard method.
Tannoid content correlates linearly with the content of haze-forming polyphenols and with chill haze produced after defined accelerated aging. In a set of beer samples of one brand having different degrees of stabilization, a high correlation was determined between test results and long-term colloidal stability.
The modified test can be used as a rapid and simple test for checking the stabilization process. It is particularly suitable for Pilsner type beer of long (more than 6 months) colloidal stability controlled by stabilization on the side of polyphenols.