Determination of Sorbic Acid in Cheese by High Performance Liquid Chromatography

Sorbic acid (E, E-2, 4-hexadienoic acid) is added as a preservative to cheese because of its fungistatic and antimicrobial activity.

A facile method for the analysis of sorbic acid that is applicable to sliced processed cheese and grated cheese products.

A cheese sample and dry-ice mixture was blended and sorbic acid was extracted with methanol and analyzed by HPLC-ultraviolet with external standardization. A large sample size was used to overcome sample inhomogeneity due to imprecise sorbic acid addition techniques during production and sorbic acid migration through the fat over time.

The method was shown to be accurate for both processed cheese and grated Cheddar cheese, with acceptable spike recovery (93.7, 103.7%, respectively), and no bias (α = 0.05) against an international reference method (p = 0.59, p = 0.13, respectively) was found. Acceptable precision was confirmed for both processed cheese slices and grated Cheddar cheese, with repeatability of 5.3% and 4.3% relative standard deviation, respectively, and intermediate precision Horwitz ratio values of 1.3 and 1.7 for processed cheese slices and grated Cheddar cheese, respectively. Method detection limit and ruggedness experiments further demonstrated the suitability of this method for routine compliance testing.

A method for high-throughput, routine testing of sorbic acid is described. The method was subjected to single-laboratory validation and was found to be accurate, precise, and fit-for-purpose.