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

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).