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Fungi Associated D With The Spoilage Of Cocoyam (colocasia Esculenta)
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A wide range of micro-organisms (Particularly moulds) have been
associated with cocoyam decay, relatively few are implicated as
primarily pathogens (Aderiye and Ogundana, 1984). The degree of
pathogenicity varies and is highly dependent upon storage conditions. It
has been stated that fungi take the lead in the spoilage of cocoyam
during storage. (Nwufo and Atu, 1987). Under these storage conditions,
the fungi which are liable to attack cocoyam include; Fusarium solani,
Botryodiplodia, theobromae, Rhizopus, stolonifer, Aspergillus niger,
Sclerotium roltsii, Trichoderma hamatum andPythium species. (Nwufo,
1980,Uwgunwanyi and Obeta, 1996). Another factor also attributed to the
spoilage of cocoyam is high respiratory activity. Storage temperature to
an optimum of 70C and 85% relative humidity increases the storage time.
The crops are usually left in the ground and harvested when need, and
there is a limit to how long the crop can be left in the soil since the
corms and cormels sprout and produce new growth, which result in the
cocoyam losing its good values.
Therefore, it has been suggested that
November and March /April are the ideal time for harvesting cocoyam.
However, due to the difficulties in storage, cocoyam are usually
utilized or consumed fresh shortly after harvest because of these fungi
which lead to their spoilage during storage, (Passam, 1982, and Onwueme,
1987). The objective of this study is to investigate the fungi
associated with the spoilage of post harvest cocoyam during storage at
ambient temperature (28 ± 20C).
Cocoyam leaves are consumed as green
or dry vegetables and the stem is either cooked or eaten on its own or
together with other dietary staples or pound into flour. The leaves are
consumed because they are rich in protein and vitamins while the roots
is rich in carbohydrates and minerals, (Duru and Uma, 2002).
Large
quantities of carbohydrate-rich solid waste are produced in the course
of processing cormels into starch and this constitute a waste disposal
problem, (Duru, 2000).
The changing economic, social, political and
cultural values of the world have challenged all countries to
efficiently use their resources.
In Cameroon, two types of cultivated
cocoyam varieties can be differentiated based on the colour of the
flesh. The white –flesh cultivar or white cocoyam is the main cultivated
variety because of its early maturation (6-(months) and high yield. In
addition, the white cocoyam is most preferred in diet because of its
excellent taste. The pink-flesh variety or red cocoyam is rarely grown
because of its long maturation process (12-16months) Despite its
importune, white cocoyam is highly susceptible to cocoyam root with
attendant yield losses > 90%. In contrast, fields observations by
farmers revealed that the red cocoyam has a certain degree of field
tolerance against the cocoyam root rot disease (Tambong, 2000).
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ABSRACT - [ Total Page(s): 1 ]Fungi associated with the spoilage of cocoyam (Colocasia esculenta) during storage at ambient temperature (28+20c) was investigated in this study. This was done by cutting the damaged portion of the cocoyam tubers and blend with diluents (water) to have even distribution of the microorganism and ensure ease of plating out. This done with the sample and inoculation was done from the 4th test tube on SDA medium and incubated for three to seven days at the temperature 0f 270c. The isolate with the ... Continue reading---
