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The study assessed changes in nutritional content of some commonly consumed traditional vegetables subjected to postharvest processes. Amaranth (Amaranthus cruentus L.), black nightshade (Solanum scabrum Mill.) and jute mallow (Corchorus olitorius L.) leaves used as vegetables were subjected to blanching, boiling and drying. The proximate composition and β‐carotene content of fresh and processed leaves were determined. Amaranth, black nightshade and jute mallow leaves had 25.21%, 39.74% and 29.18% of protein, respectively. The β‐carotene levels were 16.40, 25.25 and 27.74 mg/100 g for black nightshade amaranth and jute mallow leaves, respectively. The ash content was 10.57% for black nightshade, 12.40% for jute mallow and 16.33% for amaranth. Processing methods caused decreases of β‐carotene and crude lipid content. Boiling for 30 min or more resulted in large loss of β‐carotene. Drying under shade resulted in less loss of β‐carotene than drying in cabinet at 50 and 60°C.

Nutritionally, contaminant iron in foods may lead to overestimation of the satisfaction of iron requirement while iron deficiencies remain a widespread health problem. Iron contamination was measured in millet and sorghum grains after decortication and in-field milling using different equipments in Burkina Faso. Total iron content did not change significantly after decortication, probably due to a balance between losses resulting from the removal of iron-rich peripheral parts and contamination. Total iron contents increased significantly after mechanical milling irrespective of whether iron or corundum grindstones were used. Contamination was highly variable, ranging from 3 to 6 mg iron/100 g DM, and was mainly due to wear of the milling equipment. After in vitro digestion of traditional cereal dishes prepared with iron-contaminated or uncontaminated flours, the contaminant iron was found mainly in the insoluble fraction. Only in sorghum was a small proportion (4%) bioaccessible, showing that contaminant iron has poor nutritional interest.

Summary Two non‐GMO biofortified and one traditional pearl millet varieties were compared in abrasive decortication studies to evaluate their potential for increasing iron and zinc content. The phytate‐to‐mineral ratios were used to estimate mineral bioavailability. Iron and zinc contents in the biofortified varieties Tabi and GB8735 were two to threefold higher than in the traditional variety. Iron content reached 7.2 and 6.7 mg per 100 g DM in the biofortified varieties, which corresponds to the target values of biofortification programs. Zinc content was, respectively, 5.6 and 4.1 mg per 100 g DM in the GB8735 and Tabi varieties. Because of the presence of phytate and other chelating factors that were only partially removed during decortication, there was no improvement in iron bioavailability in the biofortified varieties. But whatever extraction rate, phytate‐to‐zinc ratios ranged between 6 and 18; zinc absorption could be improved by using these biofortified varieties for food processing.

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