The evaluation of Fourier transform infrared (FT-IR) spectroscopy and multivariate data analysis techniques for quality control at aniIndustrial cellar

[摘要] ENGLISH ABSTRACT: The alcoholic beverage industry needs objective analysis of grape juice and liqueur quality. Fourier transform infrared (FT-IR) spectroscopy with multivariate data analysis techniques is widely used in wine laboratories across South Africa for accurate, fast and high sample throughput analyses. In this study the potential of FT-IR spectroscopy is evaluated for the quantification of ammonia in freshly pressed grape juice. FT-IR spectroscopy is evaluated, using two different spectrometers, in respectively attenuated total reflection (ATR) - and transmission scanning modes for the quantification of alcohol, pH and invert sugar in spirit-based liqueurs. The ultimate aim was to implement the PLS regression algorithms developed at an industrial cellar and replace the complex and lengthy reference methods used at the time of this study. Principle component analysis (PCA) was performed prior to the calibration step to identify groupings and patterns within the spectra. The PLS calibration models were developed from samples collected at the cellar and using partial least square (PLS) regression. The models were evaluated using the performance criteria coefficient of determination (R2) and root mean squared error of cross validation (RMSECV) at calibration stage, and root mean square error of prediction (RMSEP) and residual predictive deviation ratio (RPD) at validation stage.The average RMSEP (1.88 mg/L) of the ammonia PLS calibration model was in agreement with the standard error of laboratory (SEL = 1.54 mg/L). The R2 (92.05) and average RPD (3.3) proposed a model with excellent precision for screening purposes that was ready to be transferred for use by the laboratory.The r2 values for the alcohol, pH and invert sugar PLS calibration models obtained in ATR and transmission, indicated good to excellent precision (80

[发布机构] Stellenbosch University