Thermorésistance des spores de<i>clostridium tyrobutyricum</i>et<i>Clostridium butyricum</i>

Abstract

Summary Clean spores suspensions of 3 strains of Clostridium tyrobutyricum were prepared after culture in dialysis sacs. The survivor curves of the spores heated at 90 °C in 0·033 M phosphate buffer (pH 7·0) or in skim-milk were logarithmic. From the thermal-death-time curves the following values were calculated: D at 121 °C = 0·003−0·012 min and z = 8·4−10 °C when spores were heated in phosphate buffer; D at 121 °C = 0·006−0·008 and z = 9·5−9·9 °C when spores were heated in milk. When clean spores of 2 strains of Clostridium butyricum were heated at 85 °C in 0·005 M phosphate buffer (pH 7·0) the survivor curves were logarithmic, but ‘tails’ were observed after heating in skim-milk. The value of D at 85 °C was lower than that obtained with spores of C. tyrobutyricum .