Construction of a model for the rapid detection of acids in strong-flavor original Baijiu based on mid-infrared spectroscopy technology

In order to realize the rapid grading and quality control of strong-flavor (Nongxiangxing) original Baijiu, a rapid detection model for the content of total acid, caproic acid, acetic acid and butyric acid in strong-flavor original Baijiu was established by Fourier transform mid-infrared spectroscopy (FT-MIR) combined with partial least square (PLS) method. The optimal principal component numbers of the model were screened by relative error share, and the model were tested. The results showed that the coefficients of determination R² of the quantitative models for total acid, caproic acid, acetic acid and butyric acid were more than 0.90, the root-mean-square error (RMSE) of both the calibration set and the prediction set was less than 0.041 g/L, the optimal numbers of principal component were 9, 19, 8 and 9, respectively, and the relative errors of the quantitative models were less than 10% for total acid, caproic acid and acetic acid and less than 51% for butyric acid. In summary, the prediction model of total acid, acetic acid and caproic acid based on mid-infrared spectroscopy had good prediction ability, which could provide data support and theoretical basis for the rapid grading and quality control of strong-flavor original Baijiu.