The Acid Hydrolysis of Lactose and the Preparation of Hydrolyzed Lactose Sirup

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Abstract
A study was made of the factors " affecting the hydrolysis of pure solutions of lactose by heat. The velocity constant (K X 104) for the reaction varied with the time and temp. of hydrolysis and the acid and lactose conc. of the solns. Values for K X 104 ranged from 11 at 100[degree] C to 1904 at 165[degree] C. HCl was used in concs. of 0.001 to 1 mole per 1000 gms. of soln. and it was found to be a more effective catalyst than citric acid. There was a progressive destruction of lactose and of the newly formed hexoses during hydrolysis. This destruction was accelerated by conditions of excessive or prolonged heating and when high sugar and acid concs. were used. Directions were given for the prepn. of a hydrolyzed sirup from lactose. A solubility curve for galactose in aqueous glucose solns. at 25[degree] C was presented. The solubility of glucose at 25[degree] C was 50.8%, galactose 32.09% and a mixture of equal parts of both hexoses 42%. The max. conc. of the 2 hexoses which was soluble at 25[degree] C was 58.3%, consisting of 49.8% glucose and 8.5% galactose. The lactose in skim milk, whey or crude lactose, cannot be hydrolyzed without the use of excessive quantities of acid and the production of undesirable protein decomposition products.