Blackwell Publishing Journal Backfiles 1879-2005
Process Engineering, Biotechnology, Nutrition Technology
Summary. The diffusion coefficients of water, Dw, and acetone, Da, in aqueous solutions of malto-dextrin have been determined over a range of moisture contents of the malto-dextrin above 10%. At a few selected moisture contents, the diffusion coefficients of ethyl acetate, benzene, carbon tetrachloride, camphor and methane have also been determined. Diffusion coefficients were derived from measurements of sorption and desorption by a malto-dextrin layer.The diffusion coefficient was found to be dependent on both the moisture contents and the size of the diffusing molecule. Over the range of moisture contents investigated, log Dw was found to be proportional to Cw-1 and log Da proportional to Cw-1/2, where Cw is the concentration of water (kg/m3) in the malto-dextrin. For the compounds studied, the logarithm of the diffusion coefficient measured at a moisture content of 20.1% was found to be approximately proportional to the molecular ‘diameter’ of the diffusant.This knowledge helps to explain the phenomenon of flavour retention during the drying of liquid foods.
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