(1) Field of the Invention
This invention relates to a process for preparation of beta-lactose.
(2) Description of the Prior Art
The treatment of alpha-lactose monohydrate with various alcohols at their boiling points (at normal atmospheric pressure) led to the quantitative conversion to anhydrous alpha-lactose. This latter form of lactose does not possess the high solubility in water of beta-lactose. Subsequently, alkaline alcoholic media, at the boiling point of the alcohol, were used resulting in quantitative formation of beta-lactose. The disadvantage of this procedure is that it requires extensive washing of the beta-lactose product with alcohol in order to remove the caustic media. If the caustic media is not removed completely, the beta-lactose would not be usable, and could be harmful, in food formulations.
P. F. Sharp, U.S. Pat. No. 2,319,562, discloses a process for heating solid alpha-lactose monohydrate at temperatures of 130.degree. C. or higher leading to the quantitative formation of a form of alpha-lactose with greater solubility in water than the lactose monohydrate. The disadvantage of this procedure is that at the temperature required to remove the water of crystallization the lactose undergoes some decomposition resulting in a brown colored product.
Beta-lactose can be produced by crystallization from an aqueous solution above 93.5.degree. C. The disadvantages of this procedure are, that large amounts of lactose remain in the mother liquor because of the high solubility of beta-lactose in water, and residual water in the product can lead to formation of considerable amounts of alpha-lactose monohydrate.