Kinetics of the Synthesis of Lactose Molecular Compounds

¹ Laboratoire de Physicochimie et Génie Alimentaires, Ecole Nationale Supérieure d'Agronomie et des Industries Alimentaires, 2, Avenue de la Forêt de Haye, 54500 Vandoeuvre les Nancy, France

We studied the molecular compounds 5/3ß-lactose and 3-/2ß-lactose, which are due to the physical and chemical association of the two anomeric forms - and ß-lactose. The kinetic parameters of the synthesis were determined: the order of the reaction, the rate constant, and the energy of activation. A nondestructive method employing X-ray diffraction was used for the quantification of lactose in the solid state. The synthesis of 5-/3ß-lactose was almost three times faster than that for 3-/2ß-lactose. Furthermore, the activation energy for the synthesis of 3-/2ß-lactose was twice as high as that for 5-/3ß-lactose. The observed differences could be explained by different synthesis pathways.

Key Words: kinetics • lactose • methanolic medium • molecular compounds

Submitted on October 27, 1997
Accepted on July 17, 1998