Anti-Nutrient, Phytochemical and Antiradical Evaluation of 10 Amaranth (Amaranthus spp.) Varieties Before and After Flowering

摘要

Amaranth ( Amaranthus spp . ) vegetable is widely consumed in Kenya and contributes to the alleviation of food insecurity. It is reported to have bioactive components such as antioxidants that help in protecting the body from long-term degenerative diseases. However, amaranth vegetable has also been shown to contain some anti-nutrients such as tannins, phytic acid, oxalates and nitrates which may bind nutrients and reduce their bioavailability in the body. There are many amaranth varieties and there is very little information about differences in the anti-nutrient and phytochemical levels among the varieties. The objective of this study was to determine the phytochemical and anti-nutrient content of ten amaranth varieties at two growth stages, before and after flowering. The study was in Jomo Kenyatta University of Agriculture and Technology. Ten amaranth varieties, eight of which are new varieties, were planted. Harvesting was done in two stages, at vegetative stage and post flowering stage. The leaves were analyzed for nitrates, vitamin C, total carotenoids, flavonoids and total antioxidant activity. Results showed decrease in nitrates which reduced by about 40% as the plants matured. The leaves also increased antioxidant activity as the plants matured with the concentration equivalent (IC 50 ) with DPPH of 2 mg/mL at vegetative stage and about 1mg/mL after flowering. In conclusion, as the plants grow older, there was an increased accumulation of anti-nutrient and other plant chemicals. Antioxidant activity is however increased.