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Synthetic antioxidants and metallic elements as additives/contaminants in virgin palm oil

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Overview

Olafisoye and colleagues measured synthetic antioxidants and twelve metallic elements in virgin palm oil sampled from fifteen plantation locations in southern Nigeria. The antioxidant screen found no detectable BHA, BHT, EEMC, or propyl gallate, while ICP-OES detected aluminum (Al), Co, cadmium (Cd), chromium (Cr), Cu, Fe, Mn, nickel (Ni), lead (Pb), Se, tin (Sn), and Zn in the oil matrix. Lead, cadmium, and tin are the most relevant HMI signals: Pb ranged from 0.006 to 0.847 in the authors’ table units, Cd from 0.127 to 0.762, and Sn from 0.090 to 161.576, with the paper warning that most samples exceeded cited WHO vegetable-oil limits for several metals.

Key numbers

  • Sample set: 15 virgin palm oil samples from Abak, Acharu, Agbarho, Ago-Emokpae, Apoje, Badagry, Benin City, Igede-Ekiti, Ikire, Iresaapa, Nsukka, Okitipupa, Onishere, Ubiaja, and Umuabi plantations or sampling areas.
  • Metal scope: Al, Co, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Se, Sn, and Zn by ICP-OES after oil-water micro-emulsion preparation.
  • Pb in oil, Table 3b: 0.006 ± 0.001 at Ubiaja to 0.847 ± 0.001 at Onishere. The paper states a WHO vegetable-oil limit of 0.01 for Pb and says most samples exceeded that limit, with Ubiaja as the exception.
  • Cd in oil, Table 3a: 0.127 ± 0.001 at Abak and Badagry to 0.762 ± 0.002 at Igede-Ekiti. The discussion states all sampled plantations exceeded the cited WHO vegetable-oil limit of 0.005 for Cd.
  • Sn in oil, Table 3b: 0.090 ± 0.004 at Agbarho to 161.576 ± 3.907 at Benin City. The abstract identifies tin as the highest-concentration element in Benin City plantation oil.
  • Ni in oil, Table 3b: 0.068 ± 0.001 at Abak to 0.786 ± 0.001 at Apoje.
  • Other reported ranges in oil, Tables 3a-3b: Al 0.018-0.833; Co 0.091-0.887; Cr 0.011-0.998; Cu 0.022-0.446; Fe 0.033-0.673; Mn 0.023-0.672; Se 0.011-0.926; Zn 0.053-1.621.
  • Synthetic antioxidant validation: LODs were 0.041 mg/L for BHA, 0.057 mg/L for BHT, 0.006 mg/L for EEMC, and 0.003 mg/L for propyl gallate; none of these antioxidants was detected in the sampled oils.

Methods (brief)

For metals, the authors weighed 0.5 g oil into polypropylene tubes, added hydrochloric acid and propan-2-ol to a 10 mL final volume, shook the mixture for 30 minutes, refrigerated the micro-emulsion, and analyzed elements by radial-view ICP-OES. For antioxidants, they extracted 0.5 g oil with acetonitrile:hexane and analyzed BHA, BHT, EEMC, and propyl gallate by RP-HPLC with UV/Vis detection at 280 nm. The source reports location-specific oil values with mean ± error terms and states that the real samples were analyzed in triplicate.

Implications

Certification: The paper is direct occurrence evidence for virgin palm oil and broader edible cooking-oil rows, especially for Pb, Cd, Ni, and Sn. Because the tables label oil values in mg/L while the abstract describes a mg/kg range, HMTc pooling should preserve the source unit until a basis conversion is explicitly adjudicated.

Courses: The source is a useful example of plantation-location variability and of why edible oils can carry metals from environmental contamination, processing, or local agricultural conditions.

App: Palm oil can be flagged as having direct literature evidence for Pb, Cd, Ni, and Sn occurrence, with Nigeria-specific geographic context rather than a global palm-oil estimate.

Microbiome: No direct microbiome endpoint.

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