Evaluation of MEMS NIR spectrometers for on-farm analysis of raw milk composition

Today, measurement of raw milk quality and composition relies on Fourier-transform infrared spectroscopy to monitor and improve dairy production and cow health. However, these laboratory analyzers are bulky, expensive and can only be used by experts. Moreover, the sample logistics and data transfer delay the information on product quality, and the measures taken to optimize the care and feeding of the cattle rendering them less suitable for real-time monitoring. An on-farm spectrometer with compact size and affordable cost could bring a solution for this discrepancy. This paper evaluates the performance of Micro-Electro-Mechanical-System (MEMS) based near-infrared (NIR) spectrometers as on-farm milk analysers. These spectrometers use Fabry-Pérot interferometers for wavelength tuning, giving them the advantage of very compact size and affordable price. This study discusses the ability of MEMS spectrometers to reach the accuracy limits set by ICAR for at-line analyzers of the milk content regarding fat, protein and lactose. According to achieved results, the transmission measurements with the NIRONE2.5 spectrometer perform best, with an acceptable root mean squared error of prediction (RMSEP=0.21% w/w) for the measurement of milk fat and excellent performance (RMSEP≤0.11% w/w) for protein and lactose. In addition, the transmission measurements using the NIRONE2.0 module give similar results for fat and lactose (RMSEP of 0.21 and 0.10% w/w respectively), while the prediction of protein is slightly deteriorated (RMSEP=0.15% w/w). These results show that the MEMS spectrometers can reach sufficient accuracy for at-line and in-line fat, protein and lactose prediction.