Abstract
The bacteriological results of Franklin, Underwood, Perkin & Burton (1970) are analysed to show that colony counts of Bacillus stearothermophilus spores in UHT-treated milk are influenced by the inhibitory action of the milk, so that the sporicidal effects of the UHT process as calculated from the results are too high. Only the elimination of the inhibitory factor will allow true sporicidal effects to be determined.