Studies on D10 Values (Y- Irradiation) of Five Postharvest Fungal Pathogens and their Effect on the Biochemical Properties of Fresh capsicum Fruits

Fungi are increasingly implicated as the agents of spoilage of economically important fruits and vegetables. Five postharvest fungi of pepper fruits namely Aspergillus niger, A. fumigatus Colletotrichum capsici, C. trumcatum and Fusarium solani were tested for their population responses to gamma irradiation. These fungi were irradiated at dose 0.2, 0.4, 0.6 and 0.8KGy at a dose rate of 1.08KGy/hour. Stumbo equation was used in generating D10 values of the organisms. The fungi were inoculated on the pepper fruits for 8 days and their biochemical/physiochemical properties (pH, total ascorbic acid, total titratable acidity and soluble solids) and physiological weight loss were assessed. Complete randomized block design was employed. GenStat 12th edition was used with one- and two-way Anova for D10 values and biochemical parameters respectively. The D10 values ranged from 0.714 to 0.995 KGy with Fusarium solani being the most radio resistant whereas Colletotrichum species were also more susceptible to the lethal effect of gamma irradiation. Generally, fungi inoculated pepper fruits had higher biochemical values compared to the control samples. Gamma irradiation decontaminated fresh pepper fruits of their bioburden thereby extending their postharvest life since these fungi when present are either pathogenic or saprophytic to the pepper fruits. Deteriorating activities of fungi also have adverse effect on the physiochemical properties of pepper fruits.