Milk and dairy products

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, UHT, 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.

Analysis of L-Lactic acid in milk and dairy products

CDR FoodLab® is the chemical analyzer for quality and process control that allows you to determine a wide range of parameters of many foods, animal feeds and pet foods. 

Method

Endpoint analysis. Analysis time: [uni]. Analysis sessions with multiple samples are possible up to a maximum of 16 tests for CDR FoodLab® and 3 tests for CDR FoodLab® Junior.<h3>Sample treatment</h3>Milk: Use milk as is. Fresh cream: Take 4 mL of cream in a centrifuge tube, add 100 µL of diluted HCl (i.e. dilute 200µL of HCl fuming 37% in 1 mL of distilled water), mix and centrifuge for 5 minutes. Take the aqueous solution and filter it, if necessary. Mozzarella or Ricotta cheese or Yogurt: Homogenize the sample. Weight exactly 4 gr of mozzarella or ricotta cheese or yogurt in a proper cup and add 40 ml of NaOH 0,25N solution. Homogenize the sample using a mixer and take the amount for testing.

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.

Test principle

Reaction involved in the analysis of lactic acid in milk and dairy products

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

Calibration curve

Lactic acid analysis in milk and dairy products with the CDR FoodLab® analysis method: correlation curve with the reference method. R² = 0.9975

Milk and Cream

Ricotta, Mozzarella and Yogurt

Reagent test kits

Measuring range

CDR FoodLab® the analyzer for quality control of food, animal feeds and pet foods. Top version

CDR FoodLab®

CDR FoodLab® the analyzer for quality control of food, animal feeds and pet foods. Junior version