Ziarati et al. 2019 — Toxic metals in Iranian and Italian flavoured olive oil
This study measured Pb, Cd, Ni, and As in 480 commercial olive oil samples purchased across three consecutive seasons from markets in Lombardy (Italy) and Tehran (Iran), comparing non-flavoured (virgin, extra-virgin) and flavoured (fungi, aroma vegetable, pepper) varieties by ICP-AES. Iranian brands consistently showed higher contamination than Italian brands, and fungi-flavoured olive oil exhibited the highest Pb and Cd concentrations, with values exceeding FAO/WHO permissible limits, while pepper-flavoured olive oil showed the lowest heavy metal levels across all analytes.
Key numbers
Italian olive oil (mean ± SE, µg/g):
- Non-flavoured: Pb 8.546 ± 0.043, Cd 0.0967 ± 0.0054, Ni 14.180 ± 0.011, As 0.00020 ± 0.00001
- Fungi-flavoured: Pb 12.3301 ± 0.112, Cd 1.004 ± 0.0123, Ni 12.349 ± 0.128
- Vegetable-flavoured: Pb 10.762 ± 0.088, Cd 0.0876 ± 0.004, Ni 10.231 ± 0.0143
- Pepper-flavoured: Pb 0.984 ± 0.091, Cd not detectable, Ni not detectable
Iranian olive oil (mean ± SE, µg/g by brand):
- Brand 1: Pb 15.893 ± 0.098, Cd 3.234 ± 0.044, Ni 12.354 ± 0.036
- Brand 2: Pb 13.892 ± 0.067, Cd 4.181 ± 0.042, Ni 10.542 ± 0.072
- Brand 3: Pb 11.209 ± 0.054, Cd 2.001 ± 0.0022, Ni 9.786 ± 0.0102
- Brand 4 (highest): Pb 18.783 ± 0.016, Cd 4.032 ± 0.014, Ni 14.444 ± 0.283, As 0.0050 ± 0.0002
Combined means (µg/g):
- Italian: Pb 8.546, Cd 0.396, Ni 12.253, As 0.00020
- Iranian: Pb 14.944, Cd 3.362, Ni 9.579, As 0.0039
- Cd in Iranian samples was approximately ten times higher than in Italian samples (p < 0.005)
Storage effect (combined samples, µg/g):
- Pb at 1 month: 14.221; at 12 months: 27.111
- Cd at 1 month: 2.989; at 12 months: 4.989
Note: The reported Pb and Cd concentrations in Italian fungi-flavoured oil (e.g., Pb 12.3 µg/g = 12,300 ppb) substantially exceed typical literature ranges for olive oil and the Codex/USDA limit of 0.1 mg/kg (100 ppb). The paper does not comment on this discrepancy. These values should be treated with caution; results may reflect contamination during sample preparation or analytical error, or the fungi flavouring additive itself may be a concentrated source.
Methods
ICP-AES (Varian Vista) for Cd, Pb, and Ni; ICP-MS (Agilent 7500c) for total As with LC-ICP-MS speciation of iAs vs organic forms. Wet digestion with HNO3/H2O2 microwave. Samples were purchased across autumn 2016, winter and spring 2017 from recognized markets in Lombardy (Italy) and Tehran (Iran). Three replicates per sample; certified reference material used for QC (recoveries >95%). As speciation identified iAs(III) and As(V) fractions, enabling separation from DMA and MMA. Reported values are dry weight. LOD established as 3× standard deviation of procedural blanks.
Implications
Certification: The finding that fungi-flavoured olive oil dramatically elevates Pb and Cd concentrations (if confirmed) would be directly relevant to HMT&C ingredient-level controls on flavoured oil products. The flavouring source (mushroom) may be the contamination vehicle rather than the base oil. Geographic origin (Iran vs Italy) creates meaningful variance in the contamination profile for olive oil and its derivatives.
Courses: Storage time as a driver of Pb and Cd accumulation (12-month values roughly double 1-month values in this dataset) is a practical supply-chain point for brand QA training.
App: Flavoured olive oils should be treated as higher-risk than plain olive oil for Pb and Cd; mushroom/fungi-flavoured variants specifically should be flagged if this finding replicates.
Caution: The quantitative values in this study are substantially higher than published literature for olive oil. They should be used to indicate direction-of-effect (fungi-flavoured > plain > pepper-flavoured; Iranian > Italian) rather than as calibration inputs for contamination profiles until independently replicated.