Changes in particle morphology during drying of drops of carbohydrate solutions and food liquids. 1. Effect of composition and drying conditions (original) (raw)

Abstract

Drying rates and the development of particle morphology were monitored simultaneously for initially uniform size drops falling through a column having a known temperature profile. A sampler with continuously flowing dimethyl sulfoxide solvent was used to determine the extents of drying of the captured particles. Measured water contents were compared with predictions of a model based upon diffusion within a noncirculating, voidless sphere. Drying rates for drops of aqueous solutions of sucrose and maltodextrin agreed well with this model, as did rates for drops of coffee extract drying a t low (189 " C ) air temperature. At higher air temperatures (219 and 254 "C), coffee drops dried at rates greater than predicted by the model. These results correspond t o observed tendencies for particles of partially dried coffee extract to exhibit residual blowholes and for suspended drops to push wet material from the interior of the drops outward through surface ruptures during drying.

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