Monitoring of total acidity content in continuous vinegar fermentation using a self-made modification of a micro-electro-mechanical system near-infrared spectrometer

This study evaluated the potential of a micro-electro-mechanical system (MEMS) near-infrared spectrometer for the on-line monitoring of total acids in the continuous fermentation process of rice vinegar and white vinegar. A self-made modification of the digital light processing NIRscan nano spectrometer was used for this purpose. As best pretreatment method, the multiplicative scatter correction was used to pretreat the raw spectra, which were subsequently subjected to a partial least square regression calibration. The results showed that total acids could be determined by this experimental setup with root-mean-square errors of predictions of 0.12% (w/v) and 0.27% (w/v) for rice vinegar and white vinegar, respectively. In conclusion, this low-cost MEMS near-infrared instrument can be applied to monitor total acids in the industrial continuous fermentation process of rice and white vinegar.