HEAT-RESISTANCE OF A NEOSARTORYA-FISCHERI STRAIN ISOLATED FROM PINEAPPLE JUICE FROZEN CONCENTRATE

Ascospores of a Neosartorya fischeri, isolated from pasteurized pineap ple juice concentrate, were tested for heat resistance in deionized wa ter, pineapple juice and pineapple juice concentrate, as well as for t he effect of ascospore age on resistance to thermal inactivation. D-85 degrees C ranged from 19.6 to 29.5 min, D-88 degrees C ranged from 12 .4 to 17.0 min, D-90 degrees C were 4.7 to 7.6 min and D-95 degrees C were 1.7 to 2.3 min. Z-values were 9.1, 9.2 and 8.9 degrees C when hea ting took place in deionized water, pineapple juice and pineapple juic e concentrate, respectively. Heating at 100 degrees C destroyed ascosp ores beyond detectable levels. Heat resistance increased as the ascopo res aged from 1 to 6 months.