Kvasny Prum. 2008; 54(4): 108-114 | DOI: 10.18832/kp2008007

How to use the NIR spectroscopy in a brewery laboratory.Peer-reviewed article

Adam BROŽ, Petr KOŠIN, Jan ŠAVEL, Josef PROKEŠ

¹ Budějovický Budvar, n. p., České Budějovice; e-mail: adam.broz@budvar.cz

² Vysoká škola chemicko-technologická v Praze, Ústav kvasné chemie a bioinženýrství

³ Výzkumný ústav pivovarský a sladařský, a. s., Sladařský ústav Brno; e-mail: prokes@brno.beerresearch.cz

The Near Infrared Spectroscopy (NIR) belongs to the group of molecular vibration spectroscopy. It is a rapid instrumental method enabling the forecast of important qualitative indicators of raw materials as well as intermediate products during beer production. In the article, attention was aimed at malt extract, malt proteins, soluble nitrogen in congress wort, relative extract at 45 °C and Kolbach index. The samples used were produced at the micromalting plant of the Research Institute of Brewing and Malting, Plc. The spectra in the NIR range were measured by the MPA apparatus (Multi Purpose Analyzer) of the company Bruker Optics, with installed OPUS 5.5 chemometric software, by means of which mathematical calibration models were made. The models were verified by internal validation, validation graphs were made, all this was followed by external validation, first with the samples from the micromalting plant, then with the samples delivered by commercial malting plants. The results were assessed on a statistical basis. For ensuring the control of models, the NIR spectroscopy represents a suitable method especially in such cases where a high number of real-time analyses without a long delay between sampling and the result of the analysis are required. From the measured spectrum, it is possible to predict more characteristics at a time. A worse precision can be compensated here by the speed of the analysis and absence of treatment of solid or liquid samples.The Near Infrared Spectroscopy (NIR) belongs to the group of molecular vibration spectroscopy. It is a rapid instrumental method enabling the forecast of important qualitative indicators of raw materials as well as intermediate products during beer production. In the article, attention was aimed at malt extract, malt proteins, soluble nitrogen in congress wort, relative extract at 45 °C and Kolbach index. The samples used were produced at the micromalting plant of the Research Institute of Brewing and Malting, Plc. The spectra in the NIR range were measured by the MPA apparatus (Multi Purpose Analyzer) of the company Bruker Optics, with installed OPUS 5.5 chemometric software, by means of which mathematical calibration models were made. The models were verified by internal validation, validation graphs were made, all this was followed by external validation, first with the samples from the micromalting plant, then with the samples delivered by commercial malting plants. The results were assessed on a statistical basis. For ensuring the control of models, the NIR spectroscopy represents a suitable method especially in such cases where a high number of real-time analyses without a long delay between sampling and the result of the analysis are required. From the measured spectrum, it is possible to predict more characteristics at a time. A worse precision can be compensated here by the speed of the analysis and absence of treatment of solid or liquid samples.

Keywords: spectroscopy, NIR, laboratory, quality, malt, validation

Published: April 1, 2008