Heat Resistance And Inactivation of Neosartorya fischeri and Talaromyces flavus ascospores in water, phosphate buffers, fruit juices and fruit juices fortified with sugars and preservatives

This work was designed to the study some heat resistance characteristics of the isolates obtained in relation to fruit processing parameters. The effect of heat (85, 90 , 92.5 0 and 95 C) in combination with common fruit products preservatives (sodium benzoate and citric acid) and sugars (fructose and sucrose) on inactivation of ascospores of N. fischeri and T. flavus was studied in water, phosphate buffers, grapefruit, orange and pineapple juices. The rate of thermal inactivation was highest in medium containing sodium benzoate. The presence of sugars (sucrose and fructose) in juices protected the ascospores against heat inactivation when compared with plain juices. Ascospores of T. flavus had D85 0 C values which ranged from 10.6 to 78.9min; D90 0 C values of <1 to 13.6min and D92.5 0 C values of <1 to 8.1min. Ascospores of N. fischeri had D85 0 C values which ranged from 61.9 to 217.5min; D90 0 C values of 5.0 to 62.6min; D92.5 0 C values of 1.1 to 19.7min and D95 0 C values of <1 to 13.6min. These results mark the high heat resistance of ascospores of heat resistant fungi isolated from the tropics. Heat resistant fungi not only cause spoilage of fruit products but also produce highly toxic and sometimes carcinogenic compounds; these findings are of utmost importance to fruit processing industries which are presently increasing in number in Nigeria and other developing countries. [N.J. Amaeze. Heat Resistance And Inactivation of Neosartorya fischeri and Talaromyces flavus ascospores in water, phosphate buffers, fruit juices and fruit juices fortified with sugars and preservatives. Report and Opinion 2012;4(2):18-26]. (ISSN: 1553-9873). http://www.sciencepub.net/report. 4