Alternative Test for Phosphorous in Cheese

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Abstract
A modified test for P in cheese based on quantitative precipitation, filtration and indirect titration of mg quantities of P is presented. The procedure was designed specifically for Cheddar cheese and was used to analyze a wide range of Cheddar samples including some with atypically high and low Ca and P. A modification of the procedure permitted measurement of total ash, Ca and P in the same cheese sample. With reagent adjustments it is possible to test other cheese varieties as well as other diary products. Average recovery of P from 10 replicate solutions containing known amounts of Ca and P was 99.1 .+-. 0.7%. Average recovery of P added to 10 replicate Cheddar cheese samples was 98.8 .+-. 1.5%. Ten Cheddar cheeses were analyzed in duplicate by the proposed method and by atomic emission. Results of the 2 methods differed by an average of 0.015% P, a significant difference, but the methods were strongly correlated (r = 0.94). Duplicate analyses by the proposed method were conducted on 54 Cheddar cheese samples ranging from 0.427 to 0.555% P. The average difference between duplicate measurements was 0.011 .+-. 0.009% P. The principle of the proposed test and modifications required for cheese analysis are discussed.