Simultaneous Measurement of Total Acid Content and Soluble Salt‐free Solids Content in Chinese Vinegar Using Near‐infrared Spectroscopy

Abstract: Total acid content (TAC) and soluble salt‐free solids content (SSFSC) in Chinese vinegar are 2 important indicators in the assessment of its quality. This paper shows the feasibility to determine TAC and SSFSC in Chinese vinegar by near‐infrared (NIR) spectroscopy. Synergy interval partial least square (Si‐PLS) algorithm was performed to calibrate the regression model. The number of PLS factors and the number of intervals were optimized simultaneously by cross‐validation. The performance of the model was evaluated according to root mean square error of prediction ( RMSEP ) and correlation coefficient ( R ) in the prediction set. The optimum Si‐PLS model for TAC was achieved with RMSEP = 0.264 g/100 mL and R p = 0.9655; the optimum Si‐PLS model for SSFSC was achieved with RMSEP = 1.93 g/100 mL and R p = 0.9302. The overall results demonstrated that NIR spectroscopy combined with Si‐PLS could be utilized to determinate TAC and SSFSC in Chinese vinegar, and NIR spectroscopy has a potential to be used in vinegar industry.