Modern process control techniques in the production of dried milk products - A review

Abstract

Advanced process control techniques are being developed for the manufacture of milk powder. Further developments depend on determining with accuracy the multivariate aspects of thermodynamic properties of a concentrated food in the course of milk powder manufacture. Viscosity must be measured and modelled as a function of total solids, temperature, time and shear rate for each product over the range of conditions encountered in the falling film evaporator and the spray dryer, and, in addition, density and heat transfer coefficients must be determined and modelled versus total solids and temperature for spray drying. Some of these parameters are difficult to measure exhaustively, due to the interactive effects of time, temperature and shear rate. Research needs to be directed at characterising the changing thermodynamic properties of milk at all stages in its transformation to powder and at identifying an appropriate mix of first-principle and empirical models. Future developments are likely to involve models for stickiness, thermodynamic models of spray drying, online monitoring of atomisation and measurement / modelling of particle surface conditions. © INRA, EDP Sciences, 2005.