Cicero et al. 2022 — Mineral and microbiological analysis of spices and aromatic herbs
This Italian study simultaneously assessed microbiological contamination and trace mineral content in 13 dried spice and aromatic herb samples purchased from an international market in Saudi Arabia, representing products sourced from India, Iran, Indonesia, and Vietnam. Mineral analysis by ICP-MS (Agilent 7500CX) quantified 18 elements including all four potentially toxic metals (Cd, Pb, As, Hg) plus Al, Ni, Cr, Sn, V, Co, Sb, Sr, Fe, Mn, Cu, Se, Zn, and Be. Microbiological analyses confirmed the samples met EU criteria for food safety pathogens. For the four regulated heavy metals, Pb was the primary concern: ajwan seeds (thymol seeds) from India showed 0.544 mg/kg, five times the EU fresh herb limit of 0.1 mg/kg. Aluminium reached 930 mg/kg in thymol seeds and 145 mg/kg in saffron, representing notable accumulation. All Cd, As, and Hg values were within regulatory limits across all 13 samples.
Key numbers
Potentially toxic elements (Cd, Pb, As, Hg) across all 13 samples:
- Cd: range 0.003–0.079 mg/kg (all within EU MPL of 0.2 mg/kg)
- Pb: range 0.008–0.544 mg/kg; two samples above EU fresh herb limit of 0.1 mg/kg
- Ajwan seeds (Trachyspermum ammi, India, sample L): 0.544 ± 0.003 mg/kg (p < 0.05 vs limit)
- Saffron (Iran, sample E): 0.096 ± 0.005 mg/kg (close to limit, p > 0.05)
- All others below 0.1 mg/kg: black pepper (Vietnam) 0.008, cinnamon (Indonesia) 0.023, organic fenugreek (India) 0.010, black cumin (India) 0.034, caraway (India) 0.043
- As (total): range 0.003–0.339 mg/kg (all within WHO limit of 5 mg/kg)
- Thymol seeds (India, sample L): 0.339 ± 0.006 mg/kg (same sample with highest Pb)
- Caraway (India): 0.078 ± 0.001 mg/kg
- Saffron (Iran): 0.086 ± 0.002 mg/kg
- Hg (total): range 0.001–0.010 mg/kg (all well below WHO limit of 0.2 mg/kg and EU limit)
Aluminium:
- Thymol seeds (India, sample L): 930.198 ± 5.269 mg/kg — extremely high
- Saffron (Iran): 145.216 ± 6.281 mg/kg
- Caraway (India): 87.507 ± 0.269 mg/kg
- Chia seeds (Iran, Tokhme Sharbati): 46.889 ± 1.678 mg/kg
- Other spices: 7–44 mg/kg
Selected additional minerals:
- Cr: range 0.021–2.357 mg/kg; cinnamon (Indonesia) 2.357, thymol seeds 1.113
- Ni: range 0.416–3.053 mg/kg; black cumin (India) 3.053, cinnamon (Indonesia) 2.766
- Sn: range < LOD–2.392 mg/kg; coriander (India) 2.392, black pepper (Vietnam) 1.174
- Sr: range 4.299–95.917 mg/kg; caraway (India) 95.917, cinnamon (Indonesia) 50.586
- Contamination sequence: Pb > As > Cd > Hg
Microbiological results: Black cumin, Iranian chia seeds, and caraway showed elevated total coliform and Enterobacteriaceae counts (some above reference limits); all samples negative for Salmonella and L. monocytogenes; no foodborne pathogens detected.
Methods (brief)
ICP-MS (Agilent 7500CX with Octapole Reaction System) following microwave acid digestion (HNO3 + H2O2 at 1000 W, 180°C, 10 min hold). Internal standard: Re at 0.8 mg/L. Validated against NIST 1570A (spinach leaves); recoveries 93–103% for all elements except Hg (92.93%). LODs ranged from 0.001 to 0.051 µg/kg; LOQs from 0.003 to 0.168 µg/kg. All analyses in triplicate. Reports total arsenic and total mercury (no speciation). Study collected from Saudi Arabian international market — products represent supply chains destined for Europe and Middle East. Regulatory comparisons against EU Regulation EC 1881/2006 and amendments (EU 1317/2021 for Pb; EU 1323/2021 for Cd) and WHO guidelines.
Implications
Certification: The 0.544 mg/kg Pb in ajwan seeds (thymol seeds) from India is five times the EU fresh herb limit and roughly 5.4 times the Australian FSANZ limit; this is a less commonly studied spice that could carry hidden lead risk. The co-occurrence of the highest Pb and As values in the same sample (thymol seeds) is consistent with a contaminated soil origin rather than adulteration. The extremely high Al in thymol seeds (930 mg/kg) warrants investigation. HMT&C supplier assessment should include thymol/ajwan seeds as an elevated-risk spice.
Courses: Illustrates that regulatory compliance on Cd, As, and Hg does not guarantee clean supply: lead exceedances can occur in smaller, specialty spice categories (ajwan, caraway) that are not commonly flagged. Also demonstrates the value of broad multi-element screening: several non-toxic but accumulation-relevant elements (Sr, Co, Sn) showed notable variation across spice types.
App: Provides ICP-MS data for 13 spice commodities across multiple metals. Thymol seeds and coriander are data points not well covered in other studies in this batch. Ajwan seeds Pb (0.544 mg/kg) and tAs (0.339 mg/kg) are notable for this commodity. Cinnamon from Indonesia shows Pb 0.023 mg/kg, Cd 0.071 mg/kg, Cr 2.357 mg/kg, Ni 2.766 mg/kg — less severe than Vietnamese/Indian cinnamon in other studies but adds geographic contrast.