Ascorbic acid retention of freshly harvested seven Nigerian green leafy vegetables after soaking in water

Vitamins are important micronutrients needed in the body for important biologic functions of which fruits and other edible plants are principal sources. The current study examined the influence of steeping on vitamin C or ascorbic acid retention (%) of seven Nigerian green vegetable leaves after 8 h. One kilogram each was purchased from Mile 3 market, Port-Harcourt, Nigeria, and brought to the Chemistry/Biochemistry Laboratory of Nigerian Stored Products Research Institute, Port-Harcourt, Nigeria. The leaves were sorted, washed and air-dried, then 6 lots of 100 g each were weighed out and treated as follow; whole leaf 1, whole leaf 2, sliced leaf 1, sliced leaf 2, sliced and salted leaf 1 and sliced and salted leaf 2. Each of treatments 1 was soaked in 100 mL of distilled water while each of treatments 2 was soaked in 200 mL of distilled water. All treatments were kept for 8 h while monitoring the trend of reduction in vitamin C contents at 2 h intervals. Moisture (%) was determined following AOAC (2002) methods while dry matter content was estimated from moisture by calculating the difference. Ascorbic acid content (mg/100 g) was determined following the method of Ndawula et al. (2004). Result showed that; moisture, dry matter, and ascorbic acid contents of raw leaves ranged from 67.63–86.70%, 13.30–32.37%, and 103.00–1199.23 mg/100 g respectively. During soaking, ascorbic acid retained by the seven green vegetables reduced as follows; 73.39–24.26% (Amaranthus viridis), 100.26–19.62% (Gnetum africanum), 129.05–27.72% (Gongronema latifolium), 66.84–7.55% (Ocimum gratissmum), 42.59–4.14% (Piper guinense), 77.38–10.26% (Pterocapus mildbedii) and 120.02–17.97% (Telfaria occidentalis). The study showed that ascorbic acid retention (%) of seven Nigerian green vegetable leaves decreases with increasing soaking duration.