Lactic acid in milk and dairy products
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Lactic acid is produced by the fermentation of lactose due principally to the microbic activity. Its concentration is correlated to the total bacterial charge; hence, a chemical test aimed to determine the concentration of lactic acid is a useful index of the good state of preservation of food. In addition, thermal treatment for example in UHT milk destroys the bacterial charge but does not modify lactic acid concentration and therefore lactic acid value can be used to investigate the "history" of the product. The test can be done even in powdered food as powdered milk, whey and additives after reconstitution with water. This chemical test is used to determine lactic acid concentration in cheese, ricotta, mozzarella, yogurt since its value has to be kept under fixed law limits.
Download pdf datasheet Lactic acid analysis on milk and dairy products
Instrument
Reagents
R1 (pre-filled in test tube): Phenolic derivatives - phosphate stopper
R1a (dropper): catalyst
R2 (lyophylic): Lactate oxidase Peroxidase
Test method
Test type End Point
Color reading at 545 nm or 505 nm
Test time: 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
Lactic acid , in presence of the lactate oxidase and the peroxidase, reacts with a phenolic derivative and forms a violet complex whose intensity, measured at 505 nm, or at 545 nm, is directly proportional to the concentration of lactic acid in the sample. CDR innovative method is simple and fast and thanks to the reduced handling of the sample, it minimizes the risks for the operator to be contaminated.
Sample
Milk as is.
Diluted samples: yogurt
Homogenized samples in a diluted soda solution: cheese, mozzarella, ricotta.
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Kit
The reagents are provided in sealed bags, each containing 10 test tubes. They have a 12 months duration, starting from the production date. Stocking requirements are described on the bag label.
Reagents do not contain dangerous solvents and are ready for use.
| CODICE KIT | VOLUME CAMPIONE | RANGE |
| *300375 (100 Test) *300376 (20 Test) |
0-50 µL homogenized cheese | 0,01-1,75 g% |
| *300204 (10 test) *300076 (20 test) |
100 µL milk as is | 2 – 200 ppM |
Datasheet
