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Volatiles retention during drying of food liquids

Authors

  • Santosh K. Chandrasekaran,

    1. Department of Chemical Engineering, University of California, Berkeley, California 94720
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  • C. Judson King

    Corresponding author
    1. Department of Chemical Engineering, University of California, Berkeley, California 94720
    • Department of Chemical Engineering, University of California, Berkeley, California 94720
    Search for more papers by this author

Abstract

The retention of trace volatile components in food liquids during low temperature drying processes is analyzed through a ternary diffusion model. Flux equations for both water and trace organic components are solved numerically for typical drying situations. Several effects are found with the ternary analysis which are not evident from a simpler binary model. The sugar-water composition gradient which develops during drying causes an appreciable transport of the trace volatile species. This transport can occur in the same direction as the transport resulting from the concentration gradient of the volatile species, or in the opposite direction, and can result in a local accumulation of the volatile species. Concentration profiles for both water and dilute volatile components were experimentally measured during nearly isothermal drying of gelled slabs of synthetic sugar solutions and natural fruit juice concentrates. The predicted internal maximum in volatiles concentration is borne out by the experiment, and a satisfactory agreement of observed with predicted volatiles retention is found, within the limits of the experiment.

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