Based on studies of Scharer's original (1938) method for alkaline phosphatase in milk, a modified procedure was developed utilizing two strengths of an organic buffer, 2-amino-2-methyl propanol. This modification, designated the AMP method, has the following advantages: (a) elimination of non-enzymatic substrate hydrolysis resulting from immersion in boiling water; (b) complete reaction of liberated phenol to form indophenol by control of temperature. pH. and volume of 2,6-dibromoquinonechloroimide; and (c) provision of a clear solution for spectrophotometric measurement following protein precipitation and filtration. The method is able to detect less than 0.1% of raw milk in pasteurized milk, and has a precision with a 1-h incubation period equivalent to the Kay and Graham method requiring 24 h incubation. A standard of 1.6 phosphatase activity units is proposed for pasteurized milk on the basis of equivalence to 2.3 Lovibond color units by the Kay and Graham method.
Studies of Scharer's Original Method for Alkaline Phosphatase in Milk with a Modification Utilizing an Organic Buffer
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D. A. SCHIEMANN, M. H. BRODSKY; Studies of Scharer's Original Method for Alkaline Phosphatase in Milk with a Modification Utilizing an Organic Buffer. Journal of Milk and Food Technology 1 March 1976; 39 (3): 191–195. doi: https://doi.org/10.4315/0022-2747-39.3.191
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