Effect of Hydration and Crystal Form on the Surface Area of Lactose

Abstract

Heating crystalline α-lactose monohydrate at 110 to 130 C, in vacuo, to form anhydrous α-lactose yielded a solid with an expanded surface area as determined by low temperature N2, or Kr adsorption. The BET area (Brunauer, Emmett, and Teller Equation. J. Amer. Chem. Soc., 60:309. 1938.) of the anhydrous sugar was 2.0 m2/g while that of original α-lactose•H2O was only .18 m2/g. Rehydration of the anhydrous form to the monohydrate by exposure to H2O vapor at .72 P0 at 25 C resulted in only a partial reduction in surface area. Only minor differences were observed among the BET areas of several solid forms of lactose and other sugars of similar sieve size indicating only minor differences in porosity or particle shape which may be related to their potential as sorbents for odorous substances in the atmosphere. © 1972, American Dairy Science Association. All rights reserved.