Simple Selective Sodium Ion Electrode Measure of Sodium in Cheese

Abstract

A selective sodium ion electrode method for measuring sodium in cheese was evaluated for accuracy, repeatability, and sensitivity. Sodium in blue, Camembert, Cheddar, processed Cheddar, Parmesan, Mozzarella, salt-free Gouda, and Swiss cheeses in duplicate was measured by ion analyzer with a selective sodium ion electrode. In preparation of samples 1g of cheese was blended in an ionic strength adjustment buffer and filtered through cheese cloth to remove foam. Sodium was measured directly on the filtrate by the selective sodium ion electrode.Cheeses ranged from .05 to 1.72% sodium by a reference atomic absorption method. Correlation of the sodium ion electrode method with atomic absorption was .99. Comparative results of the two methods differed by an average of .06±.04% sodium. Reproducibility was evaluated on 10 replicates for each cheese. Standard deviations were ≤.02% sodium for all cheeses, and coefficients of variation ranged from .006 for blue cheese to .024 for Parmesan and Camembert. Sensitivity of the sodium ion electrode method, as determined by standard additions of .5mg to 2.5mg sodium, was excellent for all cheeses. The sodium ion electrode method may offer industry laboratories a practical alternative to present methods for measuring sodium in cheese.