[Investigation on the quality indicators of beers using NIR]

Near infrared spectroscopy (NIR) has been used to determine important indicators of the quality of undeaired beers by a partial least squares (PLS) regression and stepwise multiple linear regression (SMLR). The indicators are original, real extract and alcohol contents. Absorbance spectra in transmission mode of 83 samples were obtained with 1 mm and 5 mm path-length quartz cell. The selected resolving powers are 8, 16 and 32 cm(-1). Air and water were used as background respectively. It was concluded that the calibration and prediction results are similar with different background, pathlength and resolving power. The SMLR method seems to be better than PLS method. The results of this paper provide a foundation for the application and further development of NIR on-line beer analyzer.