Isolation and Identification of Fungi Associated With Spoilt Fruits Vended in Gwagwalada Market, Abuja, Nigeria

Aim: Annual reports have shown that 20% of fruits and vegetables produced are lost to spoilage. This study was undertaken to isolate and identify fungi that are associated with spoilt fruits commonly sold in Gwagwalada market, Abuja, and recommend appropriate control measure.
Materials and Methods: The study was conducted in Gwagwalada metropolis, Gwagwalada Area Council of the Federal Capital Territory, Abuja, Nigeria. A total of 100 spoilt fruits which include pawpaw (Carica papaya), orange (Citrus sinensis), tomato (Lycopersicon esculentum), pineapple (Ananas comosus), and watermelon (Citrullus vulgaris) were purchased and examined for the presence of fungal organisms using standard methods. The data collected were analyzed using simple descriptive statistics (frequency and mean) and analysis of variance (p<0.05).
Results: Aspergillus niger had the highest occurrence in pineapple, watermelon, oranges, pawpaw, and tomatoes with a frequency of 38%. Fusarium avenaceum followed with the frequency of occurrence of 31% in fruits such as pineapple, watermelon, oranges, pawpaw, and tomatoes while Penicillium digitatum and Rhizopus stolonifer had the least frequency of 4% each in tomato; and orange and tomato, respectively. Other fungal species were identified as yeast (Saccharomyces species) (10%), Fusarium solani (8%), and Aspergillus flavus (5%). The highest prevalence rate was 70% of A. niger from orange followed by F. avenaceum of which 65% isolates were recovered from pawpaw. Other fungal organisms such as yeast (Saccharomyces species), P. digitatum and R. stolonifer were isolated with varying prevalence (40%, 20%, and 5%) from watermelon, tomato, and orange, respectively. However, there was no significant difference in the fungal load of the various fruits studied (analysis of variance=478.2857, p<0.05, F=4.680067 and df=34).
Conclusion: The pathogenic fungi species associated with fruits spoilage in this study are of economical and public health significance. A. niger causes black mold in certain fruits and vegetables. Some strains of A. niger have been reported to produce potent mycotoxins called ochratoxins that can be harmful to human beings and animals. Care should be taken during handling of these fruits and improved technology based preservation methods are suggested to enhance the keeping quality of fruits.