Real-time modeling of milk coagulation using in-line near infrared spectroscopy

This paper considers the extraction of meaningful information in real-time from near infrared (NIR) reflection measurements of coagulating milk. This information can be used for developing automatic cutting time determination. NIR spectra (1000-2500 nm) recorded during coagulation were compressed by principal component analysis. Using component scores as a function of time, two models are proposed for describing the three milk coagulation processes: kappa-casein proteolysis, micelle aggregation, and network formation. A model for the entire coagulation process and a composite model for the three individual coagulation processes were established and tested on 12 cheese batches. Both models fitted very well (R(2) > 0.99) to the experimental NIR data. An algorithmic procedure is presented that is able to provide real-time parameter estimation for a semi-empirical model describing the kinetics of the milk coagulation processes as well as determining the transition times between the three different coagulation processes. (C) 2011 Elsevier Ltd. All rights reserved.