Lactoperoxidase milk pasteurization

A major concern for foods is unwanted microbial growth that can lead to loss of the food. This is especially true for areas where inadequate refrigeration occurs. Calorimetric techniques can be used to assess microbial growth and be done in much less time and more conveniently than traditional techniques. An example is the assessment of microbial growth in milk [40]. Here, three samples are examined raw milk at 30 °C, milk pasteurized at 72 for 15 s, then taken to 30 °C and milk treated with a lactoperoxidase system (LPS)... 

The lactoperoxidase system produces various compounds for antimicrobial protection of milk, the principal one of which is hypothiocyanite (OCNS ) as a result of the lactoperoxidase-catalyzed oxidation of thiocyanate (SCN ) by H2O2. No overheating should take place during the pasteurization process, to avoid damaging lactoperoxidase . 

Antimicrobial activity lysozyme, lactoperoxidase (which is exploited as a component of the lactoperoxidase - H202 - thiocyanate system for the cold pasteurization of milk). 

The occurrence of a peroxidase, lactoperoxidase (LPO), in milk was recognized as early as 1881. It is one of the most heat-stable enzymes in milk its destruction was used as an index of flash pasteurization (now very rarely used) and is now used as an index of super-HTST pasteurization. 

Griffiths (2) studied the thermal stability of the naturally occurring enzymes in milk at temperatures between 65 and 80°C, in order to choose an enzymatic index of adequate pasteurization of milk. For the acid phosphatase, the D-values of 7.38 min at 75°C and 7.87 min at 80°C corresponded to a z-value of 6.6°C for the inactivation of lactoperoxidase, D-values of 0.80 min at 75°C and 0.075 min at 80°C corresponded to a z-value of 5.4°C for amylase (saccharifying activity), D-values of 0.85 min at 75°C and 0.45 min at 80°C corresponded to a z-value of 16.2°C. The naturally occurring enzymes in milk showed lower D-values than those found for GFPuv in the three buffers. However, a z-value of 16.64°C characterized for GFPuv in phosphate buffer solutions at pH 7.0 was similar to that obtained for amylase in milk. 

During the trial, feed samples were taken weekly and analyzed for ehemical-nutritional features. Individual DMI and milk yield were measured daily, and representative milk samples from morning milking were collected every 3-4 d and analyzed for fat, protein, lactose, urea and titratable acidity (FT120, Foss Electric, Denmark) SCC (Fossomatic, Foss Electric) rermeting properties (Formawin, Foss Electric) AR measured either on raw milk either on milk after pasteurization (80 °C x 10 ) (Calamari et al., 2003) some milk enzymes involved in the antimicrobial activity of milk or related to the udder health (GOT, GOT, LDH, lactoperoxidase and xanthine oxidase) (Calamari etal., 2003). Fecal samples were also collected at the end of each period and analyzed for pH and DM. 

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