Low-cost visible-near infrared sensor for on-line monitoring of fat and fatty acids content during the manufacturing process of the milk.

This paper describes the calibration, validation and testing process of a low-cost on-line visible-near infrared (400-1100 nm) sensor for the monitoring of fat and fatty acids content in milk during the manufacturing process of milk. The optical, mechanical and electronic designs of the sensor have been developed in Tekniker IK4 research centre just as its manufacturing process. The measurement range of the sensor is 400-1100 nm thus it covers the visible range (400-780 nm) and the short-wave near infrared (780-1100 nm). Chemometric techniques were applied with the purpose of obtaining a predictive model for each parameter correlating the spectra obtained by the sensor with the parameters analysed in the laboratory. The models were developed by Partial Least Squares Regression (PLS) obtaining one model for each parameter. The raw milk samples used in this work were provided by CAPSA (Asturias, Spain).