Spectrophotometric Determination of Hydrogen Peroxide in Milk

Abstract

Cultures of coagulase-positive staphylococci freshly isolated from milk from mastitic udders of cows and clinical sources together with Staphylococcus aureus 196E were treated with 0.05% hydrogen peroxide in reconstituted nonfat dry milk (11% solids) at 37.8, 48.9, 54.4, and 57.2 C. The same cultures were treated in milk at 54.4 C without hydrogen peroxide. Cultures isolated from clinical sources were more resistant to hydrogen peroxide treatments at 37.8 C than those obtained from milk. At higher temperatures, no relationships were observed between origin of cultures and resistance to hydrogen peroxide. Destruction rates of all cultures increased markedly with increases in treatment temperature. The cultures were more resistant to heat treatments at 54.4 C than to hydrogen peroxide treatments at this temperature. Comparisons of the resistance of the individual cultures to the different treatments showed that: those cultures which were more resistant to heat treatments at 54.4 C in absence of hydrogen peroxide were also more resistant in the presence of hydrogen peroxide at this temperature; and that there was no correlation between resistance of the cultures to hydrogen peroxide treatments at 37.8 C and resistance to treatments at 54.4 C with and without hydrogen peroxide.