DETERMINATION OF FERMENTABLE SUGARS AND NITROGENOUS COMPOUNDS IN WORT BY NEAR- AND MID-INFRARED SPECTROSCOPY

Abstract
Near-infrared (NIR) and mid-infrared (MIR) spectroscopy techniques were evaluated for the analysis of brewery worts. Good calibrations were obtained for maltose (SEPNIR 2.6 g/l, SEPMIR 2.0 g/l), glucose SEPNIR 0.6 g/l, SEPMIR 0.4 g/l) and the sum of fermentable sugars (SEPNIR 2.8 g/l, SEPMIR 2.6 g/l) with both methods. Satisfactory calibration was obtained for maltotriose (SEPNIR 1.4 g/l, SEPMIR 1.5 g/l), nitrogen (SEPNIR 122 mg/l, SEPMIR 92 mg/l) and free alpha-amino nitrogen (SEPNIR 29 mg/l, SEPMIR 23 mg/l). MIR spectroscopy gave slightly better results, but sample handling was more difficult than in the NIR region. The NIR measurement is simple and rapid and could be used for on-line process control during mashing. No sample preparation other than filtration is needed.

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