A Solubility Method for the Determination of Alpha and Beta Lactose in Dry Products of Milk

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Abstract
A method was developed for the detn. of the 2 forms of lactose in dry products of milk based upon the max. rate of soln. of lactose and the difference in solubility of the alpha and beta modifications. The essential steps consist of adding an excess of alpha-lactose hydrate to a known quantity of the sample, determining the solubility at several time intervals and extrapolating to zero time to obtain the total initial solubility. The beta-lactose content may be ascertained easily, since below 55 mmols./100 ml. of water the total initial solubility is the sum of the initial solubility of the alpha-hydrate and of the quantity of beta-lactose present. With the beta-lactose known, the alpha modification is calculated by difference from the total lactose.