L-Lactic acid, UV method

Enzymatic method for the determination of L-lactic acid. Based on the spectrophotometric measurement of NADH formed through the combined action of L-lactate dehydrogenase (L-LDH) and D-alanine aminotransferase (D-ALT/D-GPT).

This rapid and simple stereo-specific enzymatic method is used for the determination of L-(+)-lactic acid (L-(+)-lactate) in foodstuffs such as milk and milk products (e. g. cheese, yogurt), wine, beer, bread and bakery goods, baking agents and sourdough, dietetic food, fruit and vegetable products (e. g. juices, jam, tomato pulp), meat products, soft drinks and lemonades, vinegar, as well as in animal feed, cosmetics, paper and cardboard, pharmaceuticals and biological samples. See also our test kit for D-/L-lactic acid (cat. n. AK00141).

L-Lactic acid is a common final product of the metabolism of a wide variety of living organisms, including lactic acid bacteria. L-Lactate in wine is also formed during the malo-lactic fermentation ("second fermentation"). The content of L-lactate in beer indicates the presence of Lactobacilli in production. The stereo-specific measurement of the lactate forms is of high interest e. g. in the manufacturing of sour milk products in order to assess the activity of microorganisms. The content of L-lactate in liquid whole egg or in egg powder gives good information about the hygienic situation of the products. Commercial lactic acid may not contain the stereoisomeric forms in the ratio 1:1. Free L-lactic acid in the presence of water/moisture tends to form the dimer lactyl-lactate which does not react in the enzymatic determination; therefore, this material cannot be used for the production of standard solutions.