Aroma retention during the drying of liquid foods

Abstract
Summary. Factors determining aroma retention during the drying of food liquids have been investigated with the aid of a model system. Slabs of an aqueous solution of partially hydrolysed starch, containing a small amount of acetone, were dried in air and the percentage of acetone retained was measured.Acetone was lost almost exclusively during the ‘constant‐rate’ period of drying and its rate of loss could be described in terms of a binary diffusion process. At high moisture contents, the rate of loss of a component from a drying solution is mainly dependent on its volatility, while at low moisture contents the diffusion coefficient of the component becomes the determining factor.Loss of volatile components will be only very slight if, at the onset of drying, the value of the dimensionless group BiwoKwo is sufficiently large. Here BiBiwo is the Biot number for water transport and Kwo is the ratio of the equilibrium water concentration in the gas phase and the water concentration in the solution to be dried. the minimum value of the group necessary to ensure high aroma retention increases with increasing relative humidity of the drying air. This value is larger for a drop than for a slab and is equal to 22 for a droplet under normal spray‐drying conditions.

This publication has 3 references indexed in Scilit: