Kheirati Rounizi et al. 2021 - Heavy metals in sesame oils by extraction method

Kheirati Rounizi and colleagues compared sesame seed, traditional Ardeh oil, cold-pressed virgin sesame oil, and refined sesame oil for fatty-acid composition, oil-quality metrics, heavy metals, and non-cancer risk estimates. This is routeable sesame-oil occurrence evidence because Table 5 reports As, Pb, Cd, Zn, and Cu concentrations in three edible sesame-oil preparations on an mg/kg basis.

Key numbers

All heavy-metal concentrations below are from Table 5 and are reported as mg/kg. Values are mean +/- SD unless censored.

The authors report that heavy metals in sesame seed were generally much higher than in extracted oils, with a seed reduction pattern of Pb > Zn > Cu > Cd > As. Ardeh oil retained higher Pb, Cd, and Cu than the virgin and refined sesame-oil preparations, while refined oil had the highest Zn among the oil products. The paper states that As in all oil samples was below the Codex edible-oil limit cited by the authors (0.1 ppm), while Pb in all oil samples exceeded the cited 0.1 ppm limit.

Table 6 reports non-cancer risk estimates for consumption of 25 g edible oil/day by a 70 kg adult:

All reported HQ and HI values were below 1. The authors nevertheless recommend monitoring heavy-metal contaminants and imported sesame-seed quality before oil preparation because Pb exceeded the cited edible-oil limit in each oil type.

Methods (brief)

Ardeh oil was prepared by soaking sesame seed in water and salt, dehulling, roasting below 200 degrees C, grinding to sesame paste, mixing paste with water at a 10:2.2 ratio, and separating oil by centrifugation. Virgin sesame oil was produced by cold pressing at less than 40-45 degrees C and filtration. Refined sesame oil was obtained after neutralization, bleaching, and deodorization.

For metals, 0.5 g homogenized oil was digested with 5 mL 65% HNO3 and 2 mL 30% H2O2 using microwave digestion and diluted to 10 mL. Digests were analyzed by ICP-OES. Accuracy was checked with NIST SRM 1577b bovine liver; reported recoveries were 95.6% for As, 97.67% for Pb, 90.4% for Cd, 101.5% for Zn, and 98.81% for Cu. Analyses were done in triplicate.

Implications

Certification: This source supports sesame-oil occurrence routing for total As, Pb, Cd, Zn, and Cu. It is not US-market evidence and should remain jurisdiction-aware. The extraction-method comparison is useful for distinguishing traditional Ardeh oil, virgin cold-pressed sesame oil, and refined sesame oil when product form is known.

App: Route to sesame oil and the cooking-oils-other product bucket. Pb is the main issue in this source because Table 5 values remain above the cited 0.1 ppm edible-oil limit even after refining. Arsenic is total arsenic by ICP-OES and should not be treated as inorganic arsenic.

Courses: Useful for teaching processing effects, seed-to-oil contaminant partitioning, censored values, and the difference between a regulatory exceedance and a low non-cancer HI calculation.

Wiki pages this source may touch

• sesame-oil
• cooking-oils-other
• arsenic-total
• lead
• cadmium
• zinc
• copper
• index

Verification notes

This page was built from the full PDF, including the sample-preparation methods, microwave digestion section, Table 2 recovery data, Table 5 heavy-metal concentrations, Table 6 EDI/HQ/HI values, and the discussion/conclusion. The source reports total arsenic only; no arsenic speciation was performed. The paper contains an internal Pb concentration conflict: Table 5 reports Pb in Ardeh, virgin sesame, and refined sesame oil as 0.37, 0.25, and 0.20 mg/kg, and Table 6 EDI/HQ values are consistent with those Table 5 concentrations. The narrative text instead says 3.72, 2.59, and 2.33 ppm. This page follows Table 5 and the internally consistent risk table, while flagging the conflict for audit.

Page history

The five most recent substantive edits to this page. The full version history lives in git; when DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.