PREDICTION OF TRACE METALS IN CHINESE RICE WINE BY FOURIER TRANSFORM NEAR-INFRARED SPECTROSCOPY

ABSTRACT. The feasibility of near-infrared (NIR) spectroscopy for rapid determination of potassium, calcium, magnesium, zincum, and iron in Chinese rice wine was studied. The 28 samples were of different ages (1, 3, and 5 years). The content of trace metals (potassium, magnesium, zincum, and iron) was measured by atomic absorption spectroscopy (AAS) to check the accuracy of NIR determination. NIR transmission spectra were collected in rectangular quartz cuvettes of different optical path-lengths (1, 2, 5, and 10 mm). Calibration models were established by partial least squares (PLS) regression. The PLS models of the NIR spectra group of the 5 mm optical path-length gave the best calibration result. In addition, the results for potassium, calcium, and magnesium were promising. The determination coefficients of validation (R2 val) for the three trace metals were 0.81, 0.79, and 0.88, and the root mean square errors of prediction (RMSEP) were 17.40, 24.80, and 2.20 mg L−1, respectively. However, the results for zincum and iron were less satisfactory. The corresponding R2 val values were 0.51 and 0.52, respectively. Overall, the results of this study indicated that the NIR spectroscopic technique could offer screening capability for potassium, calcium, and magnesium in Chinese rice wine. Further research is needed using a larger number of Chinese rice wines over a wider range of wine age to refine the screening method