Potortì et al. 2026 — Chemical composition and safety of commercial tahini (Italy)
This comprehensive characterisation study of seven commercial tahini brands sold on the Italian market is the first to assess toxic and potentially toxic inorganic elements — including Cd, Pb, As, and Hg — alongside proximate composition, fatty acid profile, sterol profile, and essential minerals. The key safety finding is that one sample (T-1, Turkey-origin organic tahini) substantially exceeded EU limits for both Cd (0.35 mg/kg vs. limit of 0.10 mg/kg for oilseeds) and Pb (0.50 mg/kg, five times the EU fats-and-oils limit of 0.10 mg/kg). The remaining six samples had Cd and Pb at or below LOQ or at trace levels. Mercury and arsenic were detectable only in T-1 (As: 0.20 mg/kg; Hg: below LOQ based on the table). Nickel was quantified in all samples at 0.02–0.10 mg/kg.
Key numbers
Toxic and potentially toxic elements (mg/kg, n = 7 brands, 3 analytical replicates each):
| Sample | Origin | Cd | Pb | As | Hg | Ni |
|---|---|---|---|---|---|---|
| T-1 | Turkey | 0.35 ± 0.02 | 0.50 ± 0.02 | 0.20 ± 0.02 | <LOQ | 0.05 ± 0.01 |
| T-2 | Israel | 0.01 ± 0.00 | 0.01 ± 0.00 | <LOQ | <LOQ | 0.10 ± 0.01 |
| T-3 | Germany | <LOQ | <LOQ | <LOQ | <LOQ | 0.03 ± 0.00 |
| T-4 | non-EU | <LOQ | <LOQ | <LOQ | <LOQ | 0.04 ± 0.01 |
| T-5 | Lebanon | 0.02 ± 0.00 | 0.01 ± 0.00 | <LOQ | <LOQ | 0.08 ± 0.02 |
| T-6 | non-EU | <LOQ | <LOQ | <LOQ | <LOQ | 0.04 ± 0.01 |
| T-7 | Greece | 0.01 ± 0.00 | <LOQ | <LOQ | <LOQ | 0.02 ± 0.00 |
EU limits: Cd 0.10 mg/kg (oilseeds, Reg. 2023/915); Pb 0.10 mg/kg (fats and oils, Reg. 2023/915). T-1 exceeds both. LOD/LOQ for Cd, Pb, As, Hg, Ni: 0.003 and 0.010 mg/kg, respectively (ICP-MS with ICP-OES and DMA-80 for Hg). NIST SRM 1570a spinach leaves used as certified reference material; recovery for Cd = 100.75%.
Mercury note: the study measures total Hg by TDA-AAS (DMA-80). No MeHg speciation is performed. All samples had Hg below LOQ (<0.010 mg/kg).
Essential minerals: phosphorus most abundant (7,952–9,435 mg/kg), followed by K (4,160–5,191 mg/kg), Ca (1,300–5,106 mg/kg), Mg (2,094–2,925 mg/kg). Fe range 47–83 mg/kg, Zn 54–87 mg/kg. The paper provides a rare complete inorganic profile for a commercially relevant condiment/paste.
Methods (brief)
Seven brands purchased online, 2025; n = 3 analytical replicates per brand. Microwave acid digestion (HNO3 + H2O2). ICP-OES for Ca, Fe, K, Mg, Na, Zn, P; ICP-MS for Cd, Pb, As, Ni, Sn, Sb, V, Cr, Mo, Li, Be, Co, Cu, Se, Mn; DMA-80 for Hg. Seven-point calibration curves, R2 > 0.9990. Intraday and interday precision RSD < 1.3%. Main limitation: n = 7 brands, single purchase round; cannot distinguish lot-to-lot variability or full supply-chain distribution.
Implications
Certification: T-1’s Cd (0.35 mg/kg) and Pb (0.50 mg/kg) substantially exceed EU 2023/915 limits. The single outlier from Turkey-origin organic sesame paste is a critical data point for supply-chain screening requirements. Six of seven brands were near or below LOQ for Cd and Pb, indicating that well-sourced tahini can be very low in these metals. This supports using supplier origin and testing as levers. No As or Hg exceeded LOQ except T-1 (As only). Ni was uniformly low across all brands.
Courses: First comprehensive contaminant screen for tahini. Illustrates that “organic” labeling does not guarantee lower heavy metal contamination — T-1 is organic but is the worst performer, consistent with the soil-uptake mechanisms documented for sesame.
App: Provides direct concentration data for Cd, Pb, tAs, tHg (BDL), Ni in sesame/tahini. Most brands are at or below LOQ; the distribution is strongly right-skewed with one high outlier. Sesame/tahini should be flagged as low-to-moderate Pb/Cd risk under typical commercial supply, with outlier risk if origin is unverified.