Mycological analysis of rice from stores in Igbemo-Ekiti (a rice producing area) of Ekiti State, Nigeria

Abstract

Rice (Oryza sativa L.) is the most common staple food consumed in Nigeria. For health reasons people now prefer to consume the local unpolished rice over the processed foreign ones. Igbemo-Ekiti is a town that produces rice in Ekiti state and the rice is very popular amongst inhabitants of the state and beyond. The storage facilities in the town are still traditional. This work was undertaken to assess the mycological quality of stored rice from Igbemo in order to ascertain the microbiological safety. Rice samples were aseptically collected into dry sterile sample bottles from ten rice store houses in Igbemo-Ekiti (a rice producing locality) in Ekiti State Nigeria. The samples were transported to the laboratory immediately they were collected and stored at 4°C until required for analysis. Physical observations were carried out on the samples for obvious growth of moulds such as spotting, caking, discoloration and odour. The rice samples were cultured on Potato Dextrose Agar (PDA) using the pour plate and the seed distribution methods after surface sterilization in 1% hypochlorite solution. The plates were incubated at 25°C for 5 to 7 days. The result obtained showed that the major fungi isolated from stored rice samples from Igbemo Ekiti were Aspergillus niger (10%), Aspergillus flavus (10%), Aspergillus fumigatus (70%), Botrytis cinerea (20%), Fusarium sp. (10%), Mucor mucedo (90%), Penicillium citrinum (40%), Rhizopus nigricans (10%) and Trichoderma viride (10%). The fungal counts on the rice samples were found to range from 1.0 × 10² to 7.0 × 10⁵ sfu/g. It was concluded that since some of these fungi could be mycotoxigenic; there is need for a control programme for the organisms in stored rice in the study area. It was therefore recommended that storage conditions of the stores should be improved by the aid of modern storage facilities and cleanliness should be observed by frequent cleaning and fumigation of these store houses. Enlightenment campaign is necessary for the farmers and traders who handle Igbemo rice so that they can understand the consequences of mould growth on the stored rice.

Keywords: Mycological, rice, stores, Igbemo-Ekiti, fungi.