Thermal Inactivation Kinetics of Aflatoxigenic Aspergil-lus flavus and A. parasiticus Conidia Isolated from Ethiopian Hot Red Pepper Powder

Thermal food processing is known to inactivate harmful microorganisms in foods. However differ-ent microbes have varying degrees of heat resistance. During this study, thermal inactivation characteristics of aflatoxigenic Aspergillus flavus and A. parasiticus conidia isolated and charac-terized from Ethiopian hot red pepper powder were determined by the survivor curve method in digital water bath to realize their fate and stability under thermal food processing. The experiment was done at 55, 65, 75, 85 and 95 oC with exposure time of 30, 45, 60, 75 and 90 min., and also at different NaCl concentrations for A. flavus. The D-values for A. flavus and A. parasiticus ranged from 119.1-14.1 and 147-17.1 min. respectively with Z-values of 35.2 and 34.4 oC in the written order. Both fungi were found sensitive to the moist heating following the first-order kinetics model. Aspergillus parasiticus was found resistant than A. flavus. The D-values for A. flavus at 2-8 % NaCl ranged from 119.7-188.6, 36.1-41.5, 29.6-32.9, 20.4-21.7 and 45.6-48.9 min. at 55, 65, 75, 85 and 95 oC, respectively. The NaCl decreased thermal sensitivity of the conidia and affected the linearity of inactivation. These results may serve as baseline information for postharvest pepper-based food preservation. However, for its practical application, we recommend further detailed studies on respective food processing practices and food matrix.