ISOLATION AND IDENTIFICATION OF FUNGI ASSOCIATED WITH THE SPOILAGE OF TOMATOES SOLD AT GADAU MAIN MARKET

Abstract This study evaluated the fungi associated with spoilage of tomatoes. Tomato samples from Shop D had higher fungal count because of unhealthy handling, unhealthy mode of transportation and storage, while Shop C had the least fungal count because of it environment, mode of transportation and storage was much safer than that of Shop D. Sample D had the highest fungi count of 3.9x104cfu/g and sample C had the least count of 1.8x104cfu/g. This could be attributed to the fact that deterioration process increases the microbial load in fruits samples. This result from the microbial count is partially in agreement with the study conducted by Mbajiuka and Enya, (2014) who reported that the microbial densities during the four day deterioration process of tomato that the total bacterial count increased from day 1 to day 2 with an observable decrease in day 3.. This reveals the major fungal isolates belong to Candida tropicalis, Aspergillus niger, Aspergillus flavus, Penicillium species and fusarium sp (Table 4.2). This result is in agreement with the result obtained by Mbajiuka and Enya, (2014) who reported on the isolation of 11 fungi such as Aspergillus niger, Rhizopus stolonifer, Botrytis cinerea, Penicillium notatum, Asperigillus fumigatus etc from tomato fruit. Ibrahim et al. (2011) isolated Aspergillus niger as one of the major fungi responsible for the production of volatile compounds in spoilt tomatoes. Akinmusire (2011) reported that Rhizopus spp were associated with the spoilage of tomatoes. Wogu and Ofuase (2014) isolated Aspegilliusspp, Penicillumspp, Fusarium sppand Saccharomyces spp from spoilt tomato fruits. Ugwuet al. (2014) discovered absence of microorganisms in fresh healthy tomatoes but in spoilt tomatoes, they discovered 6 species of fungi; Candida tropicalis, Penicillium notatum, Aspergillus niger, Fusarium oxysporum, Absidiacorynbifera, Rhizopus stonolifer. Bashir et al. (2016) identified two fungi species; Aspergillus flavus and Rhizopus stoloniferin tomatoes. The percentage occurrence and distribution of fungal isolates accessed on the selected tomato fruits samples revealed that Candida tropicalis was the most frequently occurring fungal isolate from the tomato samples with a percentage occurrence of 33.3%, this is followed by Aspergillus with percentage occurrence of 22.2% whereas Penicillium and fusarium species had the least percentage occurrence of 11.1% (Table 4.3) Healthy tomatoes fruit should be preferred as they seldom contain microbes (Ugwuet al., 2014). Mbajiuka and Enya (2014) found abundant presence of Penicillium nalgiovense, Penicillium notatum andPenicillimexpansium among other fungi species involved in deterioration of tomatoes fruit. Penicillium and Fusarium are among the most important genera of mycotoxigenic fungi (Zain, 2011). 5.2Conclusion This study revealed that several fungi (Candida tropicalis, Aspergillus niger, Aspergillus flavus and Penicillium species, fusarium sp) are responsible for postharvest decay of tomato fruits during storage. Pathogenic microorganisms on tomato are a source of potential health hazard to man and animals following ingestion. This is due to their production of toxins which are capable of causing disease. The present study has shown that the average viable microbial counts of the selected tomato fruit samples examined are generally above the maximum allowable limit in foods for consumption (103cfu/ml). These high counts suggested heavy fungal contamination of the fruit by handling, environment and packaging materials. With the number of isolated fungi from the selected tomato fruits, it can be concluded that different fungal species occurred within the tomato fruit samples under study. Fungal spoilage of tomatoes is attributable to the high-water content, environmental conditions, state of handling, state of storage facilities, the fungal load of the handlers and the quality of the tomatoes. These fungi isolated in this study are sources of potent mycotoxins which are detrimental to health. Aspergillus niger is a source of Ochratoxin which is considered to be a potent Carcinogen, therefore spoilt tomatoes must not be consumed but disposed of, since such consumption could be detrimental to health. 5.3Recommendations Therefore, the Hazard Analysis Critical Control Points (HACCP) should be employed at every point in the postharvest chain to minimize contamination. It is, therefore, important that both the farmers who harvest the fruits into bags for transportation and the marketers take necessary precautions in preventing contamination. The general public should stop the consumption of spoilt tomato fruits. This will however, enhance reduction in the risk of microbial toxins that are detrimental to human health which are produced form these microorganisms as isolated in the course of the research. Furthermore, this research findings were based on one location, interested researcher(s) can try more than one location to know if the spoilage is affected by location, and environment. Healthy fruits were allowed to spoil before being used for the research, the researcher might as well try using already spoilt fruits to know if newer and larger number of fungi can be isolated.