Nutrient and antinutrient in contents of raw and cooked Amaranthus hybridus

Abstract

Amaranthus hybridus was grown as a leafy vegetables in four sites in Dar‐Es‐Salaam, Tanzania. Freshly harvested leaves from each of the growing sites were analyzed for proximate composition of beta‐carotene, reduced ascorbic acid, minerals iron, calcium, phosphorous and the antinutrients oxalates and nitrates. The leaves from the four sites were bulked and cooked by boiling in distilled water in the ratio vegetable to water of 1:4 then drained. The drained vegetables were analyzed for beta‐carotene, reduced ascorbic acid, iron, calcium, phosphorus, oxalate and nitrate.

Results indicated that fresh amaranth vegetables from the four sites had comparable high moisture contents ranging between 85.3% to 86.5%, protein of between 28.2% to 31.6%. The level of minerals calcium, iron and phosphorus ranged between 2062 mg/100 g and 2263 mg/100 g, 108 mg/100 g and 128 mg/100 g and 500 mg/100 g and 553 mg/100 g respectively on dry weight basis. The levels of beta‐carotene of between 25.2 mg/100 g to 37.3 mg/100 g, ascorbic acid of between 455 mg/100 g to 535 mg/100 g. Nitrates and oxalates were at levels of between 501 mg/100 g to 560 mg/100 g and 3383 mg/100 g to 4333 mg/100 g respectively on dry matter basis.

On cooking, the levels of beta‐carotene did not change significantly but there were significant reductions (P < 0.05) in the levels of ascorbic acid of up to 50.4%, and 41.4% for phosphorus, while the total nitrate was reduced by 39.2%, and the oxalate by 40.2%. The study established that Amaranthus hybridus leaves grown in four sites of Dar‐Es‐Salaam were good sources of nutrients, had low nitrates levels but high oxalate contents. Furthermore the cooking losses of the nutrients were not excessive, while the antinutrients were substantially reduced.