Asian Journal of Food Research and Nutrition

The effect of room temperature storage on the microbial contents of oranges marketed in Owerri was investigated. The major cause of loss in perishable produces such as the orange fruit include certain pathogenic fungi (Aspergilus niger, Rhizopus sp. Trichophyton sp, Fusiform and Candida tropicalis) and Bacteria (Staphylococcus aureus, Erwinia sp and Bacillus cereus). A total of 24 fresh orange fruit samples were randomly purchased from four (4) different markets in Owerri (six oranges from each). They were processed and inoculated onto sabouraud dextoose agar, Nutrient agar and MacConkey agar by pour plate method. Multiple dilution method was also done for most probable number of coliforms. The result of the study showed that Relief market’s orange fruit sample has the highest number of bacterial counts [20% (174)]. Its yeast and mould counts were 74.4% (646) and 5.5% (48), respectively. This was followed by Ekemegbu market’s orange fruit samples with 21.5% (127) bacteria count, 71.5% (423) yeast count and 7.1% (42) mould count. Then Ekeonuwa with 24.4% (120) bacteria count, 64.8% (319) yeast count, and 10.8% (53) mould count. Following this was the Akwakuma market’s orange fruit samples with 8.1% (53) bacteria count, 82.6% (541) yeast count, and 9.3% (61) mould count. While the other bacteria organisms such as Staphylococcus aureus and Erwinia sp gradually disappeared, Bacillus cereus with Candida tropicallis increased in number in all the markets’ orange fruit samples. This is due to the comparatively lower pH in orange juice since the juice usually show a noticeable decline towards acidity during spoilage. Bacillus was present till the last day of observation (11^th day) because they can survive, grow and sporulate despite changes in water activity, pH and temperature.