Validation of Enzytec™ Liquid D-Lactic Acid for Enzymatic Determination of D-Lactic Acid in Selected Foods and Beverages: Official Method 2024.06 First Action
Year: 2025
Type: article
Abstract: BACKGROUND: D- and L-lactic acid are produced naturally by lactic acid bacteria and are found in fermented milk products, pickled vegetables, and cured meats. D-lactic acid is formed by some microorganisms only, e.g., Lactobacillus lactis and Leuconostoc cremoris. D-Lactic acid is not formed or only in traces by "higher organisms," e.g., by animals. Therefore, the presence of D-lactate may serve as an indicator for microbial contamination or spoilage, assuming that fermentation techniques have not been used. OBJECTIVE: To validate the performance of the Enzytec™ Liquid D-Lactic acid for the determination of D-lactic acid in food and beverages such as milk and (fermented) milk products, fermented vegetable products, wines, beer, fruit and vegetable juices, and eggs and egg powder. METHODS: The kit contains two ready-to-use components, which makes handling easy and suitable for automation. D-lactic acids react in the presence of NAD and D-lactate dehydrogenase to pyruvate and NADH. The NADH formed is equivalent to the amount of D-lactic acid converted. RESULTS: Ascorbic acid, 3-hydroxybutyric acid, and sulfite interfere at concentrations higher than 0.2, 0.2, and 0.05 g/L, respectively. Oxaloacetic acid, pyruvic acid, and D-fructose do not interfere at or below concentrations of 0.2, 1, and 10 g/L, respectively. The calculated LOD when using a test volume of 100 µL is 5.4 mg/L, and the LOQ is 15 mg/L. The practical upper measurement range is 600 mg/L. Relative intermediate precision was between 3.5 and 5.7% for pineapple juice, sauerkraut juice, wine, and liquid egg. A reference material (wine) showed recoveries of 108%. For automation, three applications with different test volumes were validated. Linearity is given from 0.75 up to 3125 mg/L. CONCLUSIONS: The method is robust and accurate and was approved as an AOAC Official Method of Analysis℠. HIGHLIGHTS: The ready-to-use components of the test kit have a shelf life of at least 24 months.
Source: Journal of AOAC International
Authors: Markus Lacorn, Thomas Hektor
Institution: R-Biopharm (Germany)
Language: English
Subfield: Food Science
Domain: Life Sciences
Open Access status: hybrid
Estimated APC paid: $1,868
OpenAlex ID: W4409783559