Abstract
Industrial spray drying of milk powder production utilises high solids feed at around 50wt.% or higher; however there are only a few fundamental studies investigating the droplet drying behaviour. The present work studied the shrinkage behaviour of 50wt.% skim milk droplet during drying. Temperature effects on both shrinkage kinetics and total diameter reduction were found to be different from low solids milk drying. A high drying temperature at 110°C led to negligible droplet shrinkage at X range between 1 and 0.3kg/kg. An increase in temperature resulted in larger particles after drying. The high initial solids could sustain the droplet shape and hinder solute diffusion; as such droplet shrinkage behaviour deviates from the description of ideal shrinkage kinetics. A general correlation of shrinkage coefficient b was established for skim milk with initial solids content of 10–50wt.%, useful for estimating droplet shrinkage kinetics within this range.
Published Version
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