Impact of antioxidant spices on vitamin B9 and β-carotene in steamed sweet potato leaves
Leafy vegetables provide essential nutrients for human beings. However, these nutrients are lost during cooking. Spices, which have good antioxidant activity, were cooked with sweet potato leaves to appreciate their impact on nutrients losses prevention. Sweet potato leaves were steamed during 20 min with 4 spices: turmeric, nutmeg, Guinea pepper and cloves. Vitamin B9, β-carotene and total phenolic content were determined on spices and sweet potatoes cooked without and with spices. Free radical-scavenging, inhibition power of lipid peroxidation and reducing power were also determined. The results showed that turmeric contained the most elevated total phenolic content (1633.33 mg gallic acid equivalent (GAE) g-1 dry matter (DM)) and Guinea pepper the least one (69.58 mg GAE g-1 DM). However, after steaming process, total phenolic content in sweet potatoes without spices (174.75 mg GAE g-1 DM) decreased with turmeric (41.66 mg GAE g-1 DM) and increase until 625.83 mg GAE g-1 DM with cloves. There was a loss of vitamin B9 in sweet potato leaves steamed with cloves. Indeed, the value in sweet potato without spices (0.23 mg 100 g-1) decreased up to 0.02 mg 100 g-1. But, with the other spices, there was a retention in the leaves. β-carotene used to increase in sweet potato leaves steamed with turmeric, cloves and nutmeg. However, it decreased with Guinea pepper. Free radical-scavenging inhibition percentage at 50% was about 0.50, 0.268, 4.17 and 21.50 in sweet potatoes steamed with cloves, Guinea pepper, nutmeg and turmeric respectively. The capacity of spices and steamed sweet potato leaves to inhibit lipid peroxidation was higher than that of Gallic acid (reference). But, their reducing power capacity was lower than that of the reference (vitamin C). Vitamin B9 and β-carotene are useful for human well-being and antioxidant spices contribute to reduce their losses during sweet potatoes leaves steaming.
Agbo, A.E., Meite, S., Gbogouri, G.A., Gouekou, A.D., Kouame, C.E., Kouassi, K. and Brou, K. (2020). Impact of antioxidant spices on vitamin B9 and β-carotene in steamed sweet potato leaves. Acta Hortic. 1292, 383-392
leafy vegetables, cooking, nutrients losses, prevention, retention