Detection of Residues of Hydrogen Peroxide in Pasteurized Cream

A method used to detect hydrogen peroxide in milk was adapted by changing sample size and precipitant. Cream is mixed with tungstic acid, filtered and hydrogen peroxide in the filtrate is reacted with titanium tetrachloride to produce a stable yellow-colored complex absorbing at 415 nm. Average recovery of hydrogen peroxide from freshly prepared cream was 78% and it decomposed rapidly in refrigerated cream to 50% of original concentration in 24 h before stabilizing. Accuracy was calculated as 10% relative over the range 0-100 μg/g and repeatability was 2 μg/g. A survey of 25 commercial cream samples ex factory and tested fresh revealed that 13 contained from 10 to 60 μg of hydrogen peroxide/g. It was considered this confirmed that hydrogen peroxide had been added. Commercial indicator strips for hydrogen peroxide gave reliable indications of its presence in creams for levels above 10 μg/g.