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Mineral Content Estimation of Black Cumin Seeds

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Overview

Imperl et al. determined the mineral composition of Nigella sativa seeds sourced from a Moroccan herbal market using ICP-OES after microwave-assisted acid digestion. The study reports macro- and microelement profiles. The key finding relevant to heavy-metal surveillance is that cadmium, cobalt, nickel, and chromium were all below the limit of detection in the analyzed samples. The paper is a comparison study noting that potassium was the predominant element, followed by calcium and magnesium; iron, zinc, and aluminum were the most abundant microelements.

Species disambiguation: “Black cumin” throughout this paper refers to Nigella sativa L. (family Ranunculaceae), not Cuminum cyminum L. (family Apiaceae, true cumin). These are distinct plants that share a common name in some contexts. This source page is filed under herbs-and-spices rather than cumin.

Key numbers

Toxic metal concentrations: cadmium (Cd), Co, nickel (Ni), and chromium (Cr) were below the limit of detection in all analyzed Nigella sativa samples. No specific LOD values are stated in the available text.

Macro- and microelement findings (reported qualitatively):

  • Predominant elements: K (highest), followed by Ca and Mg
  • Major microelements: Fe, Zn, and aluminum (Al)
  • Comparative analysis against Nigella sativa seeds from other geographic origins showed variation in mineral content

The paper explicitly states: “cadmium, cobalt, nickel, and chromium were below the [LOD].”

Methods (brief)

Mature Nigella sativa seeds were purchased from a herbal market in the North-East part of Morocco. Seeds were soaked in water, washed, and air-dried. Sample decomposition by microwave-assisted acid digestion. Analysis by Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES). Accuracy was confirmed by spike recovery studies at different concentration levels.

Implications

Certification: This paper provides a non-detection result for Cd, Co, Ni, and Cr in Nigella sativa seeds from Morocco. The finding is consistent with the Tura et al. 2023 study from Ethiopia (also Nigella sativa, also no detectable lead (Pb) or Cd). The absence of toxic-metal detections in Nigella sativa seeds does not transfer to Cuminum cyminum (true cumin), which is a different plant in a different family.

Species note: This source should not be cited as cumin heavy-metal evidence. It is Nigella sativa evidence only.

Update history

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