Effect of milk fat and total solids concentration on the kinetics of moisture uptake by ready-to-eat breakfast cereal

When immersed in milk, breakfast cereal easily take up moisture, lose their brittle texture and become soggy. Earlier comparative analysis of the mois ture sorption by breakfast cereal immersed in water and milk indicated that milk solids might play an important role on the sorption kinetics. In this work, the moisture uptake by ready-to-eat corn breakfast cereal immersed i n milk solutions, reconstituted from whole and skimmed milk powder, was mea sured under isothermal conditions at 5, 30 and 55 degrees C. Dilutions betw een 0.25 and 1.5 were tested, with the factor of dilution 1 corresponding t o the standard recommended by the milk powder manufacturer. The Weibull pro babilistic model adequately fitted the experimental data by appropriate cho ice of its variable parameters. The dependence of the model parameters on t emperature and total solids concentration was assessed for both skimmed and whole milk. Fat was found to play a major role on the process mechanism, w hich was attributed to the deposition of a fat layer at the solid matrix su rface, hindering water and solids uptake. Yet, for short times, moisture up take proceeded at a similar rate both in skimmed and whole milk.