Lacorn Markus, Hektor Thomas
R&D Food&Feed, R-Biopharm AG, An der Neuen Bergstr. 17, 64297 Darmstadt, Germany.
J AOAC Int. 2025 Jul 1;108(4):595-611. doi: 10.1093/jaoacint/qsaf020.
Produced naturally by lactic acid bacteria, L-lactic acid is found in many fermented milk products and also in pickled vegetables, cured meats, and fish. It serves as a quality parameter in wine, beer, whole egg, whole egg powder, and juices.
To validate the performance of the Enzytec™ Liquid L-Lactic acid for the determination of L-lactic acid in food and beverages such as milk and (fermented) milk products, fermented vegetable products, wines, beer, fruit and vegetable juices, egg, and egg powder.
The method is based on enzymes that are part of a prepackaged kit that contains two ready-to-use components which are suitable for automation. L-lactic acids react in the presence of NAD and L-lactate dehydrogenase to pyruvate and NADH. The NADH formed is equivalent to the amount of L-lactic acid converted.
Ascorbic acid, 3-hydroxybutyric acid, and sulfite were found to interfere at concentrations higher than 0.2, 0.05, and 0.05 g/L in the test solution, respectively. Oxaloacetic acid and D-fructose do not interfere at concentrations at or below 0.2 and 10 g/L, respectively. The calculated LOD when using a test volume of 100 µL is 3.8 mg/L and the limit of quantitation is 10 mg/L. The practical upper measurement range is 600 mg/L. Relative intermediate precision was between 3.0 and 7.3% for pineapple juice, sauerkraut juice, wine, and liquid egg. Certified reference materials (cream cheese and wine) showed recoveries between 100 and 104%. For automation, three applications with different test volumes were validated. Linearity is given from 0.75 to 3125 mg/L.
The method is robust and accurate for manual and automated applications. The method was approved as an AOAC Official Method of Analysis℠.
The components of the test kit have a shelf life of at least 24 months.
L-乳酸由乳酸菌天然产生，存在于许多发酵乳制品中，也存在于泡菜、腌肉和鱼类中。它是葡萄酒、啤酒、全蛋、全蛋粉和果汁的质量参数。
验证Enzytec™ 液体L-乳酸在测定食品和饮料（如牛奶和（发酵）乳制品、发酵蔬菜制品、葡萄酒、啤酒、果蔬汁、鸡蛋和蛋粉）中L-乳酸含量方面的性能。
该方法基于预包装试剂盒中的酶，该试剂盒包含两个即用型组分，适用于自动化操作。L-乳酸在NAD和L-乳酸脱氢酶存在下反应生成丙酮酸和NADH。生成的NADH与转化的L-乳酸量相当。
发现抗坏血酸、3-羟基丁酸和亚硫酸盐在测试溶液中的浓度分别高于0.2、0.05和0.05 g/L时会产生干扰。草酰乙酸和D-果糖在浓度分别为0.2 g/L及以下和10 g/L及以下时不会产生干扰。使用100 μL测试体积时计算得出的检测限为3.8 mg/L，定量限为10 mg/L。实际测量上限为600 mg/L。菠萝汁、酸菜汁、葡萄酒和液体蛋的相对中间精密度在3.0%至7.3%之间。有证标准物质（奶油奶酪和葡萄酒）的回收率在100%至104%之间。对于自动化操作，验证了三种不同测试体积的应用。线性范围为0.75至3125 mg/L。
该方法对于手动和自动化应用均稳健且准确。该方法被批准为AOAC官方分析方法℠。
试剂盒的组分保质期至少为24个月。
