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Tech. Q. Master Brew. Assoc. Am., 1993, 30(2), 45-47. English, sp

A flow injection analyzer for determining the bitterness unit of wort and beer.

Sakuma, S., Kikuchi, C., Kowaka, M. and Mawatari, M.

The development and testing of a flow injection apparatus for the automatic determination of wort or beer bitterness are described. Samples of degassed beer or dilute filtered wort are injected into a carrier stream of water containing a surfactant. Immediately thereafter, isooctane and 0.6 N hydrochloric acid are simultaneously added. Mixing in a Teflon tube is followed by separation of the organic phase by means of a Teflon membrane and the measurement of absorbance at 275 nm. Evaluation of the precision of the method, using sets of 100 subsamples from the same sample, yielded coefficients of variation of 0.5 for a beer sample and 0.7 for wort. Comparison with the standard method of the American Society of Brewing Chemists ("Beer 23A" in Methods of Analysis, 7th ed., 1976) showed that the results obtained from identical samples by the two methods normally differed by less than 0.5 bitterness units (BU). The correlation coefficient of the two methods was 1.000.
Keywords : analysis beer bitterness flow injection wort