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

Ascospores of a Neosartorya fischeri, isolated from pasteurized pineapple juice concentrate, were tested for heat resistance in deionized water, pineapple juice and pineapple juice concentrate, as well as for the 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 heating took place in deionized water, pineapple juice and pineapple juice concentrate, respectively. Heating at 100 degrees C destroyed ascospores beyond detectable levels. Heat resistance increased as the ascopores aged from 1 to 6 months.