Display omitted •NIR spectroscopy was applied for monitoring fermentation process of mulberry vinegar.•The calibration performances of two kinds of NIR spectrometers were compared.•The total acids and total polyphenol content can be determined by NIR spectroscopy.•A low-cost MEMS NIR spectrometer can obtain a good prediction performance. This study evaluated the potential of Micro-Electro-Mechanical System (MEMS) and optical fiber Near-Infrared (NIR) spectrometers as a rapid method for monitoring total acids (TA) and total polyphenol content (TPC) in the fermentation process of mulberry vinegar. The NIR spectrometers Digital Light Processing (DLP) NIRscan Nano EVM (MEMS instrument) were used for this purpose, and another NIR spectrometer NIRQuest 512 was used for comparison. The standard Normal Variate (SNV) was selected as the best method used to pre-process spectra, and the competitive adaptive reweighted sampling (CARS) was applied to optimize wavelength variables, which were then subjected to partial least squares (PLS) regression. The results showed that TA and TPC could be determined. For TA, NIRQuest 512 provided a good predictive performance with the root-mean-square error of prediction set (RMSEP) of 0.22% and the R-squared of prediction set (R2P) of 0.977, whiles DLP NIRscan Nano EVM obtained the RMSEP of 0.32% and R2p of 0.950. For TPC, the NIRQuest 512 provided a predictive performance with the RMSEP of 8.11 mgGAE/L (mg gallic acid equivalent/L) and R2P of 0.820, and DLP NIRscan Nano EVM had the RMSEP of 8.22 mg GAE/L and R2p of 0.800. In conclusion, the low-price MEMS NIR instruments DLP NIRscan Nano EVM can be applied to monitor TA and TPC in the fermentation broth of mulberry vinegar.