For rapid, direct determination of D-lactic acid concentrations in food and beverage samples as well as biological samples.
Note: Requires access to pipettes for dilution. We offer pipettes that can be purchased separately: 20 uL Pipettes (Catalog: TP-20), 100 uL Pipettes (Catalog: TP-100), or 400 uL Pipettes. (Catalog: TP-400)
Fast and sensitive. Use of 20 or 100 µL sample. Semi-quantitative measurement between 0-180 mg/L (undiluted) D-lactic acid.
Convenient. No expensive lab equipment needed.
Sample treatment and assay can be performed in under 15 minutes.
Wine, beer, milk, etc
Approximately 15 min
LACTIC ACID, or lactate, is generated by lactate dehydrogenase (LDH) under hypoxic or anaerobic conditions. D-lactate is produced in only minor quantities in animals and measuring for D-lactate in animal samples is a means to determine the presence of bacterial infection. Furthermore, since D-lactate is a specific indicator of bacteria fermentation, its measurement can be used to determine the freshness of milk, meat and fruit juices. Elevated levels of D-lactate in wine is an indication of lactic acid bacteria contamination. BioAssay Systems QuantiQuik™ D-Lactate Test Strips are based on D-Lactate dehydrogenase catalyzed oxidation of D-lactate in which the formed NADH reduces a chromogenic reagent. The intensity of product color, is directly proportional to D-lactate concentration in the sample.
What samples have you tested?
The strips have been tested on red wine, white wine, homogenized whole milk, cultured buttermilk, yogurt, malt mash, beer and lemonade.
My sample turns the strip very dark purple, how can I determine the D-lactate concentration?
Very dark purple indicates that the diluted sample concentration is greater than 180 mg/L. To obtain a more accurate concentration, the sample should be further diluted and retested. For example, if the sample was diluted 5×, try diluting 21×.
I don’t have access to a pipetteman. How can I accurately measure out my samples?
We offer exact volume transfer pipettes as an accessory. For samples requiring a 21× dilution, order the 20 µL transfer pipettes (TP20). For samples requiring a 5× dilution, order the 100 µL transfer pipettes (TP100).
Can I store unused reagents for future use?
Yes, unused reagents can be stored according to the assay protocol. The strips should be kept in a dry, cool location and protected from light.
I am running sour beer samples and know that there should be high levels of lactate in the samples. However, the strips are very patchy and only have color in the corners. What is wrong?
The enzymes in the strips need to be around pH 7 to work properly. Your sour beer may be too acidic, so please adjust the pH with NaOH or another base until it is pH ~7 and rerun the strips. If the levels are quite high, you may also want to dilute the sample in water which will make the sample closer to pH 7 as well since high levels of lactate “max out” the strip.
Li, F et al (2021). Limosilactobacillus balticus sp. Nov., Limosilactobacillus agrestis sp. Nov., Limosilactobacillus albertensis sp. Nov., Limosilactobacillus rudii sp. Nov. And Limosilactobacillus fastidiosus sp. Nov., five novel Limosilactobacillus species isolated from the vertebrate gastrointestinal tract, and proposal of six subspecies of Limosilactobacillus reuteri adapted to the gastrointestinal tract of specific vertebrate hosts. International Journal of Systematic and Evolutionary Microbiology, 71(2). Assay: D-Lactic Acid in limosilactobacillus frementation cultures.