Interactions of Low Molecular Weight Adsorbates on Lactose

Lactose may serve as a carrier of food flavor, but little is known about its interactions with adsorbates. The adsorptive capacity and binding mechanism of stable anhydrous a-lactose have been investigated in low molecular weight adsorbates. Alcohols adsorb in the highest concentrations, followed by esters and ketones, while aromatic hydrocarbons with n-aliphatic side chains adsorb in the least concentrations. Data are presented for the amounts of substances adsorbed and desorbed over 10 mo. Mixtures involving two, four, and eight components exhibit varying amounts of adsorption and desorption over 10 mo. First order kinetic plots for the compounds in the eight component mixture revealed that there were discontinuous rates of desorption throughout the 10 mo. We suggest there may be at least three distinct mechanisms to account for this variance in the desorption process. Alcohols are adsorbed preferentially over aromatic hydrocarbons when both are in a mixture or when the alcohol is equilibrated with the lactose first. Aromatic hydrocarbons may adsorb on lactose if equilibration with the hydrocarbons is before that with the alcohol. These studies suggest that two active sites are located on the lactose molecule, and their spatial relationship is discussed. Experimental evidence indicates there is a finite limit as to amount of adsorbate sorbed under the conditions employed.