Overview
Ofori and colleagues processed seven cereal and root and tuber crops bought in Accra into flours intended for composite bread and pastry flour, and measured arsenic, copper, iron, mercury, lead and zinc by flame AAS, plus aflatoxins. Arsenic and mercury were below 0.01 mg/kg in all flours, and lead was quantified only in water yam and millet flour.
Key numbers
- Lead: millet flour 0.05 ± 0.01 mg/Kg and water yam flour 0.02 ± 0.01 mg/Kg; < 0.01 mg/Kg in the other five flours (Tables 1 and 2, dry weight).
- Arsenic and mercury: < 0.01 mg/Kg in all seven flours (Tables 1 and 2).
- Iron up to 201.40 ± 0.14 mg/Kg in millet flour (Table 2).
- Cadmium was not measured.
Methods (brief)
Crops were cleaned, dried and hammer-milled into flour in the laboratory. Three grams were dry-ashed at 550 °C, dissolved in nitric acid and read by flame AAS (Buck 210VGP), including arsenic and mercury. Spike recoveries were 93 to 97%; metal LODs are not reported.
Evidence Fitness
One laboratory-made flour per crop, analysed in duplicate, with no CRM and no cadmium. Arsenic and mercury by flame AAS at a 0.01 mg/kg threshold is a weak test. These flours are a proxy for blueberry-muffin and doughnut ingredients and do not measure the baked goods; the text also contradicts the tables on copper and on arsenic and lead detection.