Abstract:
The effect of Aloe vera gel on microorganisms associated with the deterioration of sweet orange (Citrus sinensis) fruits was investigated. Sweet orange fruit were obtained from selected markets and farm in Akure, Nigeria. Microorganisms associated with the deterioration were identified using microbiological techniques. A total of nine fungi and six bacteria were isolated from the orange fruits. Fungal isolates include Aspergillus flavus, A. niger, Fusarium oxysporium, Penicillium digitatum, Rhizopus stolonifer, P.italicum, Mucor mucedo, Saccharomyces cerevisiae and Geotrichium candidatum, while the bacterial isolates were Staphylococcus aureus, Escherichia. coli, Bacillus cereus, B. substilis, Serratia marcesens and Pseudomonas aeruginosa. A. niger had the highest rate of occurrence (25.3 %) among the isolated fungi, while S. cerevisiae had the least rate of occurrence (2.9 %). The average fungal counts ranged from 2.4 ×103 sfu/g to 5.3×103 sfu/g and those of bacteria count ranged from 1.4 × 105 cfu/g to 3.6 × 105 cfu/g. The
orange fruits from the King’s market had the highest (bacterial and fungal) counts while those from Federal University of Technology, Akure research farm had the lowest count. Pathogenicity test revealed that R. stolonifer, P. digitatum, P. italicum, A. flavus, F. oxysporium were able to induce spoilage in an apparently healthy orange. The proximate analysis of apparently of healthy sweet orange fruits revealed ash content (1.60 %), moisture content (83.32 %), crude protein (9.80 %), fat content (3.15 %), fibre content (10.75 %) and carbohydrate (9.51 %), Mineral content analysis showed that apparently healthy orange had 1.28 % iron, 9.68 % magnesium, 196.60 % potassium, 23.20 % calcium and 23.92 % sodium. The study also revealed that Aloe vera gel was partially effective in controlling the growth of the microorganisms. Good agricultural practices,
adequate storage facilities and good handling practices must be put in place to reduce the incidence of microbial spoilage of sweet oranges so as to increase agricultural output, profits and maintain food security.
