Effect of drying and cooking on nutritional value and antioxidant capacity of morogo (Amaranthus hybridus) a traditional leafy vegetable grown in South Africa

摘要

Morogo (vegetables in Tswana) is a green leafy vegetable from the Amaranthaceae family that can be harvested from wild growing or cultivated. The objective of this study was to determine the nutritional value, the total antioxidant capacity and selected bioactive compounds present in morogo leaves, and evaluate the effect of drying and cooking. Results showed that morogo contained a significant amount of protein (3.6 ± 0.1 g/100 g FW) and minerals which the level exceed 1% of fresh weight. The total antioxidant capacity (μmole TE/ 100 g FW) determined by DPPH and FRAP assays were 118.3 ± 15.3 and 128.4 ± 11.9 respectively. Total polyphenols (109.4 ± 7.5 mg GAE/100 g FW), vitamin C (36.6 ± 1.0 mg /100 g FW) and carotenoids represented by β carotene (25.3 ± 1.3 mg /100 g FW) and xanthophylls (7.48 ± 0.31 mg /100 g FW) formed a significant part of bioactive compounds content of morogo leaves. Since the boiling can cause significant losses of compounds in the boiling water, it can be recommended to avoid cooking methods that can include a boiling step with discard of boiling water.