Wild edible yams from Madagascar: New insights into nutritional composition support their use for food security and conservation

Abstract

Yams (Dioscorea species) are an important food resource in Madagascar, where both cultivated winged yam (D. alata) and wild edible yams are consumed. However, there is limited knowledge on the nutrient composition of wild edible yams in Madagascar, and on how they compare with the cultivated winged yam. Therefore, in this study, nine wild edible yam species, one with two subspecies from Madagascar (D. bako, D. buckleyana, D. irodensis, D. maciba, D. orangeana, D. pteropoda, D. sambiranensis subsp. bardotiae and subsp. sambiranensis, D. seriflora, and Dioscorea species Ovy valiha), were analyzed for their nutrient composition, compared with cultivated D. alata. They include 6/6 of the most favored wild edible yam species in Madagascar. New nutrient composition data (protein, carbohydrate/starch, energy, lipid, β-carotene, and minerals) are presented for these nine wild edible yam species. The results show that they contain comparable levels of lipids and starch to D. alata, but none are better sources of protein than D. alata. The results show that D. irodensis contains a significantly higher β-carotene content when compared to all other edible yams analyzed, and that D. buckleyana, D. irodensis, and D. sambiranensis subsp. bardotiae have a higher calcium content than cultivated D. alata, while all nine wild edible yam species analyzed contain a higher iron content, compared to cultivated D. alata. The nutrient composition data presented could provide new incentives to conserve wild edible yams and inform on strategies to select Dioscorea species for sustainable cultivation and use, providing opportunities to enhance future food security in Madagascar.

Keywords: Dioscorea; carotenoids; macronutrients; micronutrients; minerals; protein; yams.

FIGURE 1

β‐Carotene content of nine wild edible yam species and cultivated Dioscorea alata across eight harvest seasons, expressed as β‐carotene equivalents (μg/100 g dry weight) for mean values (n = 6–8) + SEM. *Significantly different from D. alata (p < .01).

FIGURE 2

β‐Carotene content of separated parenchyma and periderm tissue of two wild edible yam species and cultivated Dioscorea alata across four harvest seasons, expressed as β‐carotene equivalents (μg/100 g dry weight) for mean values (n = 3) + SEM. *Significantly different from D. alata in each harvest season (p < .01).

FIGURE 3

Mineral (a: calcium, b: iron, c: zinc) content of nine wild edible yam species and cultivated Dioscorea alata across four harvest seasons. (n = 3–4) + SEM.