Full Length Research Paper

The drying effect of colour light frequencies on the nutrient and microbial composition of cassava

O. M. Kolawole¹*_, B. J. Adeyemi¹, R. M. O. Kayode² and T. B. Ajibola³

¹Department of Microbiology, University of Ilorin, P.M.B 1515 Ilorin, Kwara State, Nigeria.

²Division of Biotechnology, Department of Food Science and Home Economics, P.M.B 1515, University of Ilorin, Ilorin, Kwara State, Nigeria.

³Department of Physics, University of Ilorin, P.M.B 1515 Ilorin, Kwara State, Nigeria.

*Corresponding author. E-mail: tomak74@yahoo.com.

Tel.: +234-8060088495.

Accepted 25 February, 2009

   Abstract

The drying effect of varying light frequencies on the proximate and microbial composition of cassava was investigated. Drying was carried out using the solar fabrication designed by the Department of Physics, University of Ilorin. The results of the various physicochemical parameters revealed significant difference between the mean temperatures of the colour frequencies compared with the control (p < 0.05). The colour black recorded the highest moisture content (67.0%) while deep purple had the lowest (57.0%). The results of the proximate composition showed that deep purple had the highest crude protein content (4.21%), black had the highest percentage carbohydrate (92.64%) and white had the highest vitamin C content as compared with the control. Also deep orange (3.03%), deep yellow (0.72%) and light purple (2.79%) had the highest crude fat, crude fibre and ash respectively compared with the control. It was revealed that these colours were significantly different (p<0.05) from the control. A total of 6 bacterial species were isolated from cassava. These are Staphylococcus aureus, Staphylococcus epidermidis, Micrococcus luteus, Lactobacillus lactic, Lactobacillus brevis and Proteus vulgaris. The total bacterial count was highest in light brown and lowest in deep yellow. The bacterial isolates were widely distributed in light green (5) and least in light blue and the control (2). The 5 fungi isolated from the cassava are Aspergillus niger, Aspergillus flavus, Rhizopus stolonifer, Mucor racemosus and Fusarium oxysporium. The fungal isolates were widely distributed in white (4) and least in black (1).

Key words: Drying, frequencies, cassava, proximate, microbial.