Does the milk redox potential correlate with the variability of microbes and somatic cell counts?

The objective of this study was to determine the response of thermodynamic milk property to a bacterium metabolism and somatic cell concentration. Red ox potentials were investigated in 208 milk samples with different somatic cell concentration and in 92 milk samples with various bacterium compositio ns. The following parameters were determined: the start level of the redox potential as well as the level after adding 10, 20 and 30 mug of 1,4-benzoq uinone (pbc) to the samples. From 92 samples, 61 were free of microbes and in the remaining 31, differen t bacteria were found: 18 samples contained Staphylococcus, one Staph haemo lyticus, one Streptococcus, 9 Corynebactenium, and 2 Coliforms. The analyse s of the redox potentials showed the advantage of thermodynamic stability o f the bacterium-free milk samples, compared with the microorganism-containi ng milk. it is visible in the lowest zero potential (133.8 mV), and the sli ghtest slope after the addition of pbc. In contrast, the initial values of the Corynebacterium-containing milk were significantly higher (167.5 mV); a fter pbc addition the potentials showed a more intensive decrease. There wa s no significant influence of the investigated range of somatic cell concen tration on the thermodynamic property of milk.