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Determining the original gravity using near-infrared spectrometry and cryoscopy
C∨ejka, P., Kellner, V., C∨ulik, J., Jurkov, M., Horak, T., Polednkov, M.

Close-range near-infrared spectrometry enables the determination of a few analytical values in the wort or in beer. The advantages of this technique include the speed of the determination, the small volume of the sample, the non-destructive nature of the determination, and the suitability of the apparatus for multiple purposes. One disadvantage, however, is the relatively high purchase price. The work involved taking 86 beer samples and comparing the near-infrared spectrometry results for them produced using RAPITEC, a device made by the company Nicolet, with the results for them produced by the analysers SCABA and DSA 48. The applied method supplied better results than DSA 48 but worse results than SCABA. However, the differences were so small that near-infrared spectrometry can be recommended for routine practice. Cryoscopy was tested as the second method. Using a set of 81 beer samples, the original wort was determined with the help of the ADVANCED 3D3 made by the company Advanced Instruments, and the apparent extract was determined using the densitometer DMA 55 made by the company Anton Paar. These two values were used to calculate the content of alcohol, of real extract and of extract from the original wort, and the results were compared with the traditional distillation method. This revealed a high level of correspondence between the two methods.

Descriptors: Beer, Determination of alcohol, beer analysis, near-infra-red spectrometry, cryoscopy, original gravity

Monatsschrift fr Brauwissenschaft 53, No. 11/12, 223-228, 2000