BIPHASIC THERMAL DEATH TIME CURVES AT HIGH AND ULTRAHIGH TEMPERATURES OF BACILLUS SUBTILIS HU 1 SPORES
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Abstract
Spores of Bacillus subtilis HU1 suspended in whole milk and /or distilled water subjected to high and ultrahigh temperatures ranging from 85 to 14°C. Resulting survivor and thermal death time (TDT) curves were shown to be non-linear for all temperatures investigated; convex survivor curves at most heating temperatures were observed. TDT curves observed in all studies were concave and biphasic. The z-value using milk as the menstruum were 57°C for heating temperatures of 121-140°C, and 20°C, for heating temperatures of 110-121°C. Distilled water as the menstruum yielded z-values of 58°C and 16°C for heating temperatures of 120-140°C and 110-121°C respectively.
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