For the rapid and specific concurrent assay of L-lactic acid (L-lactate) and D-lactic acid (D-lactate) in beverages, meat, dairy and food products. (100 determinations per kit; 50 of each).
INTRODUCTION:
D- and L-lactic acid are found in many foods and beverages. Produced naturally by lactic acid bacteria, D- and L-lactic acid are found in many fermented milk products such as yoghurt and cheese, and also in pickled vegetables, and cured meats and fish. L-Lactic acid is supplemented into foods and beverages (E270) where a tart flavour is desired, and is widely used as a non-volatile acidulant. In the egg industry, L-lactic acid is a quality indicator, where levels above
200 mg/kg indicate spoilage by contamination or incubation. Similarly, the quality of milk and fruit juice can be established by measurement of the D- and L-lactic acid content. In the wine industry, the course of malolactic fermentation is monitored by following the falling level of
L-malic acid, and the increasing level of L-lactic acid. The production of D-lactic acid can indicate wine spoilage. In the chemical industry, both D- and L-lactic acid are raw materials in the production of
compounds such as polylactides and biologically degradable polymers, and applications also exist for these acids in cosmetics and pharmaceuticals.
KITS:
Kits suitable for performing 50 concurrent determinations of D- and L-lactic acid are available from Megazyme. The kits contain the full assay method plus:
Bottle 1: (x2) Buffer (25 mL, pH 10.0) plus D-glutamate and sodium azide (0.02% w/v) as a preservative.
Stable for > 2 years at 4°C.
Bottle 2: (x2) NAD+.
Stable for > 5 years at -20°C.
Bottle 3: D-Glutamate-pyruvate transaminase suspension
(2.2 mL).
Stable for > 2 years at 4°C.
Bottle 4: L-Lactate dehydrogenase suspension (1.1 mL).
Stable for > 2 years at 4°C.
Bottle 5: D-Lactate dehydrogenase suspension (1.1 mL).
Stable for > 2 years at 4°C.
Bottle 6: D-/L-Lactic acid standard solution (5 mL, 0.15 mg/mL of each) in 0.02% (w/v) sodium azide.
Stable for > 2 years at 4°C.