The food
groups include fruits (banana, water melon, orange and apple),
leafy and fruity vegetables (garden egg, tomato, onion, African
spinach (Corchorus olitorius), pumpkin leaves (Telfairia occidentalis)
and ‘sokoyokoto’ (Celosia argentea)), tubers (yam and sweet
potato), legumes (soybean, bean and groundnut) and cereals (rice,
maize and wheat). Each food item was purchased by systematic
random sampling from three to six different stores. A subsample
of each was obtained for analysis. Only wholesome samples were
included for the analysis. More so, only edible portions were
included, whereas bruised or rotten parts were removed. Samples
were carefully washed in de-ionised water to remove sand and
other impurities. They were then drained and oven-dried at
100 C to a constant weight, taking care not to overheat the samples.
The dried samples were homogenised using Kenwood blender
(model BL335, Watford, UK) and stored in clean dry air-tight polyethylene
bags until analysis.