Computation of specific optical rotation from carbohydrate composition of exudate gums Acacia senegal and Acacia seyal

Specific optical rotations of 185 Acacia gums are computed from carbohydrate data by a method based upon a linear theory proposed by the authors. Agreement with observed values is in general excellent and, moreover, the differences between the observed and computed values provide a powerful intuitive tool for assignment of individual gum samples to taxonomic categories. This feature is built into the theory that characterises a well-defined category of polysaccharides with a ‘rotation operator’, which linearly translates carbohydrate data into specific optical rotations. Acacia senegal samples are clearly shown to belong to two varieties occurring together in most gum producing areas of Africa.