Created on Wednesday, 03 November 2010 13:41

L-Lactic acid in milk

Lactic acid is produced by the fermentation of lactose mainly through microbial activity. Its concentration depends on the total bacterial count and can be a useful indicator of the good state of preservation. In addition, the heat treatment at high temperatures, such as UHT milk, reduces the microbial load but does not alter the concentration of lactic acid, which thus becomes an indicator of the "history" of the product. The test can also be run on derivatives in powder (whey, milk, additives) after reconstitution in water.


FoodLab Touch easy, rapid and reliable analysis of milk and dairy productsFoodLab Touch: allows you to easily perform a wide panel of analyses in milk and dairy products.
It is not necessary skilled staff nor a laboratory for the analysis.
Results are correlated with reference method results.
It is free of service and maintenance cost .
You can also perform analysis of egg, tomato, vegetable purees, cheeses and fats.


Test type: End Point
Colour reading at 545 nm or 505 nm
Time of test: 8 minutes:
It is possible to carry out several test sessions with a maximum of 14 samples.
Calibration can be performed by aligning the test to reference values.

Test principle

Ac.L-Lactic + der. Fenolico lactic acid reaction chinoneimina + H2O

L-Lactic acid is oxidized to pyruvate by an enzymatic reaction that produces H2O2. H2O2, in the presence of peroxidase and a phenolic derivate, forms a colored complex whose intensity was read at 545nm and is directly proportional to the concentration of L-lactic acid in the sample.

Calibration curve

Comparative tests on samples of whole milk between the reference method and the FOODLAB method, performed in a leading company in production of milk, confirmed a very good alignment between the two systems.

Lactic acid test in milk: FoodLab vs Reference Method


Reagent test kit *300075 suitable for 100 tests, contains:

  • 1 box includes: 5 x reagent test kit *300076.

Reagent test kit *300076, suitable for 20 tests, contains:

  • R1: 2 packages with 10 pre-filled cuvettes with 1 mL of buffer.
  • R1a: dropper with an activator.
  • R2: dropper with enzymatic solution.


Use milk as is
Diluted samples: yogurt.
Homogenized samples in a diluted soda solution: cheese, mozzarella, ricotta.

Measuring range
(mg/L ac. lattico)
Sample volumeResolution
(mg/L ac. lactic)
2 - 200 100 µL 0,1 +/- 5% CV<3%

For samples with a value of lactic acid >200 ppm (milk) or >150 ppm (cream) use half of the sample volume (50 μL) and multiply the result by 2.

Click and Discover more about FoodLab Touch:
Tests in few minutes, reference methods compliant.
Easy to use also by unskilled staff


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