A high-solids steam injection process for the manufacture of powdered infant milk formula
2013
Murphy, Eoin G. | Tobin, John T. | Roos, Yrjö H. | Fenelon, Mark A.
Introduction of more energy efficient processing practices, such as increasing the initial solids content from which powder is manufactured, is of interest to the infant formula industry. This study evaluated the use of an inline rotor-stator mixer followed by direct steam injection to disperse and heat-treat (110 °C, 3 s) high-solids (60% w/w) formulations, for the production of powdered infant milk formula. As a control, 30% w/w infant milk formulations were subjected to a typical process, i.e. heat treatment in a tubular heat exchanger, valve-type homogenisation, evaporation (to 55% w/w solids content) and spray drying. Both formulations were dried using a three-stage dryer with two-fluid nozzle atomisation at inlet and outlet temperatures of 187 °C and 85 °C, respectively. Formulations subjected to the steam injection process had significantly (P < 0.05) lower viscosity compared to control formulations at equivalent solids contents (55% w/w). This was partly attributed to lower levels of whey protein denaturation (76.2 ± 0.09%) compared to indirect heat treatment in the control process (87.0 ± 0.5%) as measured by high-performance liquid chromatography. Prior to spray drying, volume mean particle size of both processes was not significantly different (P > 0.05), 2.04 ± 0.22 and 1.82 ± 0.04 μm for the control and high-solids steam injection processes, respectively. Powders produced by both processes had statistically similar (P > 0.05) surface free fat content, wettability and dispersibility. The study showed that it is possible to produce quality model infant milk formula powders from a high-solids concentrate while considerably reducing process complexity. ©INRA and Springer-Verlag France 2013.
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