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

Abstract

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. EnzytecTM 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.