Validation of Enzytec™ Liquid Acetic Acid for Enzymatic Determination of Acetic Acid in Selected Foods and Beverages: Official Method 2024.01 First Action.

Background: In the food industry, acetic acid is used as a food additive acidity regulator (code E260), in the form of vinegar as a condiment and in the pickling of vegetables and other foods. For wine and juices there are threshold values for acetic acid. Enzytec™ Liquid Acetic acid is an enzymatic test kit based on acetate kinase activity for the determination of acetic acid.

Objective: The aim of this study was to validate the Enzytec method in a single laboratory for determination of acetic acid in wines, juices, kombucha, beer, sausage meat, sauces/remoulades, and culture media for microbiology.

Methods: The method was evaluated for selectivity, ruggedness, stability, LOD, LOQ, linearity, dilutability, and method performance in wine, juices, beer, kombucha, sauces, culture media, and sausage meat.

Results: The test is specific to acetic acid and shows no relevant interferences. The calculated LOD for a test volume of 100 µL is 2.2 mg/L and the LOQ is 3.8 mg/L. The practical upper measurement range is 1300 mg/L for a test volume of 100 µL. Spiking of wine, juice, kombucha, beer, sauces, sausages, and culture media for microbiology resulted in recoveries between 88 and 103%. Intermediate precision was between 1.8 and 3.8%. For automation, two applications with different test volumes and different measurement ranges were validated. Linearity was demonstrated from 8 mg/L up to 6.2 g/L (depending on the test volume).

Conclusion: The method is robust and accurate for manual and automated applications. The method was accepted as a First Action Official MethodSM.

Highlights: The ready-to-use components of the test kit have a shelf life of 25 months.