Determination of Tartaric Acid of Fruit Vinegars Using Near Infrared Spectroscopy and Chemometrics

Near infrared (NIR) spectroscopy combined with chemometrics was investigated for the determination of tartaric acid of fruit vinegars. A total of 180 samples were prepared, and 135 samples were selected for the calibration set, whereas the remaining 45 samples for the validation set. Partial least squares (PLS) analysis was the calibration method as well as extraction method for latent variables (LVs) which were employed as the inputs of least squares-support vector machine (LS-SVM) model. Simultaneously, the effective wavelengths (EWs) were selected by regression coefficients. The EW-LSSVM model was better than both PLS and LV-LS-SVM model. The correlation coefficient (r), root mean square error of prediction (RMSEP) and bias for validation set were 0.998, 0.210 and 0.003 by EW-LS-SVM, respectively. The results indicated that NIR spectroscopy combined with LS-SVM method could be utilized as a high precision and fast way for the determination of tartaric acid of fruit vinegars.