Prediction of Marked Age of Mature Vinegar Based on Fourier Transform Near Infrared Spectroscopy

To evaluate the applicability of near infrared (NIR) spectroscopy for discrimination between mature vinegar with different marked age (1 year, 3 years, and 5 years), transmission spectra were collected in the spectral range from 800 nm to 2500 nm in 1, 2, and 5 mm optical path-length rectangular quartz cuvettes with air as reference at room temperature. Discriminant models were developed based on discriminant analysis (DA) together with raw, first and second derivative spectra. The calibration result for raw spectra was better than that for first and second derivative spectra. The percentage of samples correctly classified for raw were 100% for 1 year old, 100% for 3 years old and 97.5% for 5 years old, respectively. In validation analysis, for 1 year, 3 years, and 5 years old sample groups, the percentage of samples correctly classified was 100%, 100%, and 100%, respectively. The results demonstrated that NIR spectroscopy could be used as a rapid and reliable method for classification of mature vinegar with different marked age.