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African leafy vegetables (ALVs) are thought to contain an immense variety of antioxidants, which may provide nutritional and health benefits. However, there is limited, robust, and comparable information describing their nutritional composition. The aim of this study is to determine the antioxidant potential of selected ALVs [black jack (Bidens pilosa L.) and amaranth (Amaranthus hybridus L.)] in comparison with exotic leafy vegetables (ELVs) [lettuce (Lactuca sativa L.), green cabbage (Brassica oleracea), red cabbage (B. oleracea var. capitata)]. Different nonenzymatic and enzymatic antioxidant assays were used to determine plant carbohydrates (CHOs) using high-performance liquid chromatography (HPLC), phenols (Folin–Ciocalteu), ascorbic acid, carotenoids, total antioxidant capacity (TAOC) using reducing ferric ion antioxidant potential (FRAP) and 1,1-diphenyl-2-picrylhydrazyl free radical (DPPH) assays, super oxide dismutase (SOD), catalase (CAT), and peroxidase (POD). Both amaranth and black jack produced high levels of CHOs, carotenoids, ascorbic acid, and phenols during early vegetative growth [4 weeks after transplanting (WAT)]. Similarly, SOD, CAT, and POD activity for amaranth and black jack also increased during early vegetative development. Conversely, exotic vegetables (lettuce and cabbages) only increased these antioxidants toward maturity. Overall, ALVs have produced higher concentrations of antioxidants specifically during early vegetative growth stage than the exotic vegetables. The promotion of ALVs could promote a healthy alternative especially in poor rural households.

This study investigated the efficacy of edible gum arabic (GA) and carboxymethyl cellulose (CMC) containing moringa (M) leaf extract as postharvest treatments for maintaining organoleptic quality and controlling Colletotrichum gloeosporioides on ‘Maluma’ avocado fruit. For the quality study, after the fruit was dipped into the treatments: GA 10%, GA 15%, GA 10% + M, GA 15% + M, and CMC 1% + M and uncoated fruit served as control, the fruit were then stored at 5.5 °C [95% relative humidity (RH)] for 21 days, and moved to ambient conditions at 21 ± 1 °C (60% RH) for 7 days to simulate retail condition. Quality parameters that were evaluated include mass loss, firmness, and color changes (L*, a*, b*, respectively), and sensory quality attributes, such as taste, color, mouthfeel, odor, and overall acceptability. Fruit quality study results showed fruit coated with GA 15% + M and CMC 1% + M had lower mass loss (3.66%), retained firmness (62.37 N), and color changes [L* (30.85), a* (−2.33) and b* (7.14)] compared with other treatments. In this biofungicidal study on antimicrobial properties of extracts, treatments against fungi strains using an in vitro test were investigated, which showed treatments of moringa leaf extract, GA 10% + M, and GA 15% + M suppressed radial mycelial growth of C. gloeosporioides by 30%, 28%, and 33%, respectively. In conclusion, our study demonstrated that GA 15% + M and CMC 1% + M retained fruit firmness and lowered weight loss and suppressed mycelial growth of C. gloeosporioides on ‘Maluma’ avocado fruit. These edible coatings could therefore be an alternative organic postharvest coating treatment and could potentially be commercialized as a new organic biofungicide for the avocado fruit industry.