English

Abstract

African indigenous green leafy vegetables play important role in income generation and subsistence; they are the cheapest and most readily available sources of important minerals and vitamins. On the other hand, they contain anti-nutritional factors that reduce availability of vital nutrients. This study was conducted to determine oxalates, phytates and nitrates content in commonly consumed Amaranths cruentus, Spider plant (Cleome gynandra) and African night shade (Solanum villosum) at 21, 28 and 35 days age of the plant harvest. Vegetables were planted on plots and harvested at 21, 28 and 35 days. At each stage, about 600±2 g of the edible part was harvested and standard chemical analyses procedures were followed to determine oxalate, phytate and nitrate contents. Using Statistical Product and Service Solutions (SPSS 20) data were analysed and results presented as simple means, ranges and standard deviations. Analysis of variance (ANOVA) with 5% level of significance was done to determine differences in the levels of nutrients between the vegetable varieties and three maturity stages. African nightshade Nduruma BG 16 had lowest oxalate concentrations (28.7 ± 0.1 mg/100 g) at maturity stage I while African nightshade Olevolosi SS 49 had the highest value (60.9 ± 0.9 mg/100 g) at maturity stage III. There was no particular trend for phytates in all maturity stages and in all varieties but amaranths Madiira AM 38 had exceptionally the highest values (0.7 ± 0.0 mg/100 g) at stage III of maturity. The highest nitrate content was 85.61.8 mg/100 g in Olevolosi SS 49 at maturity stage I, whereas the lowest value was 45.31.3 mg/100 g in amaranths Madiira AM 38 at stage III. There was a slight variation in antinutrients composition of the studied vegetables and the composition was generally very low. Key words: Antinutrients, indigenous vegetables, maturity stage, Tanzania.