Nutritional and physicochemical properties of stored solar-dried cowpea leafy vegetables
Preservation techniques for cowpea (Vigna unguiculata L.) leaves, a green leafy vegetable mainly consumed in the eastern and northern parts of Uganda, are still lacking. The study aimed at determining the effect of blanching, open sun and solar-drying on the nutrient content, organoleptic acceptability and physicochemical properties of cowpea leafy vegetables (CLV) during storage. Proximate composition, sensory quality and colour of the CLV were determined. No significant differences (p < 0.05) in nutrient composition were observed between drying methods, except the dietary fibre, zinc and total carotenoid content. Blanched-solar dried CLV showed higher dietary fibre and total carotenoid content compared to raw dried CLV. No significant differences (p > 0.05) in appearance, taste, flavour, and texture of dried CLV were observed, except for the fresh CLV (control). Water activity levels ranged from 0.34 to 0.54 indicative of storage stability. Positive ‘L’ colour values (37.90 to 44.95) indicative of light green to green, negative ‘a’ values (-7.28 to -4.15) for greenishness and positive ‘b’ values (3.45 to 9.25) for yellowishness for raw-dried and blanched green leafy cowpea vegetable, respectively, were obtained. Marked increases in browning index and total colour difference were observed in the dried CLV during storage. Blanching and solar drying treatment formed stable and highly acceptable vegetables during storage, which could be recommended for market.
Keywords: Acceptability, colour, nutrient content, Vigna unguiculata, water activity
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