This article brings down to spices what is explained in analytical methods for food authenticity and expands on the cinnamon case covered in landmark food fraud cases.
Table of contents
A long, ground market that is hard to see into
Spices and dried herbs combine everything that makes fraud easier: high value per kilo, long supply chains with many intermediaries and a product that is almost always sold ground or crushed, where the eye can no longer tell which plant is in the package. According to the European Commission's Joint Research Centre (JRC), the food industry uses between 70% and 80% of culinary herbs and spices, which arrive through long and complex chains. General food fraud concepts are covered in what food fraud is and how it is detected.
The cinnamon and lead case is covered in landmark food fraud cases. This article focuses on the largest European study on spice authenticity and its link with food safety.
The EU coordinated plan: 1,885 samples and almost 10,000 analyses
The European Commission organized a coordinated control plan in which 21 Member States, Norway and Switzerland sampled six products with a history of fraud: cumin, turmeric, oregano, paprika/chilli, pepper and saffron. The JRC analyzed 1,885 samples with 9,926 analyses and published the results in 2021. Sampling prioritized the first links of the chain (80% of samples at border control, importers, wholesalers and processing or packaging plants) and ground or crushed presentations, which made up 89% of the total.
Because the EU has no specific purity standards for spices, the JRC used the ISO specifications for each product (extraneous matter and total ash, among others) as a reference. ISO 927 provides for a visual examination of extraneous matter, but the report considered it unsuitable for ground samples and replaced it with DNA tests. A sample was declared suspicious when it did not meet those limits, with chemical markers as supporting evidence.
Results by product
- Oregano: 48% suspicious (142 of 295). Olive (Olea europaea) DNA was found in 80 samples, confirmed in all of them by the presence of oleuropein, a compound specific to olive. Marjoram (Origanum majorana) also appeared in 11 samples, myrtle in 3 and a starch-based filler in 1.
- Pepper: 17% (70 of 421). Thirty-seven samples (9%) contained starchy fillers such as rice, wheat, barley or buckwheat; nine contained mustard, which is an allergen, and fourteen did not reach the minimum of 4% piperine.
- Cumin: 14% (34 of 250). Seven samples contained a substantial amount of caraway (Carum carvi), with carvone as the chemical marker; others had coriander, mustard, linseed or pumpkin seed above the extraneous matter limit.
- Turmeric: 11% (34 of 316). Twenty-four samples had more than 2% undeclared plant material, mainly chilli and starchy species such as maize and rice; six had less than 2% curcuminoids, the ISO 5562 minimum.
- Saffron: 11% (16 of 141). Four samples were mostly safflower (Carthamus tinctorius) and one was marigold (tagetes); in four of those five, crocin and safranal, the compounds specific to saffron, were missing.
- Paprika/chilli: 6% (27 of 462), with maize, carrot, tomato, sunflower seed and Allium among the undeclared materials.
Overall, 17% of samples (323 of 1,885) were suspicious. The report could not identify at which link of the chain fraud occurs most: there were too few samples at border control, local markets and online to compare.
The three types of adulteration that keep coming up
Bulking or substitution with foreign plant material
This is the most frequent fraud in the European plan: olive or myrtle leaves in oregano; cereal starches in pepper and turmeric; safflower in saffron; other seeds in cumin. Besides deceiving buyers about what they purchase, it has a safety consequence that often goes unnoticed: the foreign material can be an undeclared allergen. The JRC found mustard DNA in nine cumin samples and nine pepper samples, and gluten-containing cereals (wheat, barley) among the fillers.
Unauthorized dyes: Sudan and company
Color is a commercial quality criterion in paprika, chilli, turmeric and saffron, which makes it a target for fraud. In the coordinated plan, 2% of the samples analyzed by liquid chromatography with high-resolution mass spectrometry (LC-HRMS; 25 of 1,340) contained unauthorized dyes: 8.5% in saffron, 2.2% in paprika/chilli, 0.9% in turmeric and none in pepper. Sudan I, tartrazine, allura red, sunset yellow, azorubine and auramine O, among others, were detected.
In 2005, Commission Decision 2005/402/EC imposed emergency measures for imported chilli, chilli products, turmeric and palm oil: each consignment had to be accompanied by an analytical report demonstrating the absence of Sudan I, II, III and IV. That decision no longer applies: Regulation (EC) No 669/2009 repealed it from January 25, 2010 and replaced the per-consignment report with an increased level of official controls at the point of entry. In turn, that regulation was replaced by Implementing Regulation (EU) 2019/1793, which now governs those increased controls.
Lead chromate in turmeric
Lead chromate is a yellow industrial pigment that has been used to brighten turmeric root. In the European plan it appeared in only one sample, with 2 g/kg of lead and 0.5 g/kg of chromium detected by X-ray fluorescence. The underlying problem was documented in Bangladesh: a study published in 2019 in Environmental Research found evidence of adulteration with lead chromate pigments in 7 of the 9 main producing districts, with concentrations of up to 1,152 µg/g of lead in turmeric powder. The pigment was added while polishing the root.
The second part of that story shows that analytical control does make a difference. After an intervention between 2017 and 2021 that combined public outreach, education and controls by the food safety authority using rapid lead detection equipment, the proportion of wholesale market turmeric samples with detectable lead fell from 47% in 2019 to 0% in 2021 (n = 631). In 15 mill workers, blood lead fell by a median of 30%.
The EU incorporated this risk into its contaminants legislation. Regulation (EU) 2021/1317 set maximum levels for lead in dried spices and expressly mentions, among its reasons, the fight against fraudulent practices such as adding lead chromate to turmeric. The limits are 0.60 mg/kg for fruit spices, 0.90 for seed spices, 1.0 for bud spices and flower pistil spices, 1.50 for root and rhizome spices (which include turmeric) and 2.0 for bark spices. Since 2023 they have been listed in Regulation (EU) 2023/915, which replaced Regulation 1881/2006.
How it is detected in the laboratory
The European plan combined techniques because each answers a different question. What follows complements the general overview of analytical methods for food authenticity with what is specific to spices.
Microscopy
A 2020 paper on black pepper still describes it as the reference method against infrared screening; the authors combined it with FTIR in imaging mode. Its limitation is quantification: in a study of 36 commercial saffron samples, the authors concluded that microscopic observation gives a preliminary indication of authenticity but on its own cannot measure purity.
Infrared spectroscopy (FTIR and NIR)
These are rapid, non-destructive techniques that compare the spectral fingerprint of the sample with chemometric models built on authentic material. They work well as screening: in a Queen's University Belfast study of 78 oregano samples from shops and online sellers, FTIR screening and a second test by LC-HRMS agreed 100% that more than 24% contained some adulterant. Near-infrared (NIR) is increasingly used on powdered foods, including with portable instruments. Its weakness is that an atypical result signals suspicion, not the identity of the adulterant.
Liquid chromatography with mass spectrometry (LC-MS)
It makes it possible to look for specific chemical markers: a Sudan dye, olive oleuropein in an oregano or caraway carvone in a cumin. A validated LC-MS/MS method for oregano adulterants achieved decision limits below 2% and, applied to 54 suspicious samples, found that almost 90% contained at least one bulking agent, with a median adulteration of 50%.
DNA methods
They identify the species even when the product is ground. The JRC used droplet digital PCR as a screen on all 1,885 samples, next-generation sequencing metabarcoding on 1,460 and 647 species-specific real-time PCR assays to confirm and estimate the amount of undeclared material. In pepper, a qPCR method with plant barcodes detected papaya, maize and chilli; in a market survey of 29 samples, 41% were contaminated, although about three quarters at very low levels suggesting accidental contamination. That nuance matters: DNA tells you what is there, but not always whether it was intentional. Nor does it detect dyes or minerals: lead and chromium are measured by X-ray fluorescence or ICP-MS.
Why spice fraud is also a food safety issue
On top of lead, unauthorized dyes and undeclared allergens comes the microbiological hazard. The U.S. FDA, in its risk profile on pathogens and filth in spices, reviewed 14 spice-associated outbreaks between 1973 and 2010, with 1,946 illnesses, 128 hospitalizations and two deaths. Salmonella enterica caused ten of them and 87% of the cases. Of all illnesses, 70% were linked to ready-to-eat foods in which the spice was added after the last pathogen reduction step.
In imported spice shipments offered for entry to the U.S. between fiscal years 2007 and 2009, the mean prevalence of Salmonella was 6.6% (750 g sample), 1.9 times that of all other FDA-regulated foods sampled in the same period. More than 80 serotypes were isolated. Filth (insect fragments, whole insects and animal hair) appeared in 12% of shipments, an indicator of failures in good practices. The agency also documented that Salmonella can survive for more than a year in dried spices. In 2018 it updated the profile: in 9 of 11 types of packaged spices at retail, prevalence was significantly lower than at import, which it attributed to pathogen reduction treatments applied after entry into the country.
In a chain with many intermediaries and undeclared handling, a pathogen reduction treatment may be skipped or a blend may introduce contaminated material. That is why food fraud vulnerability assessment (VACCP) and hazard analysis should look at the same suppliers. The behavior of Salmonella in dry matrices is discussed in Salmonella in low-moisture foods.
Which TAAG kits or technology relate to this matrix
The TAAG catalog does not include spice authenticity kits: it does not detect substitute plant species, dyes or lead, which require the methods described above in a specialized laboratory.
Where TAAG does connect is with the microbiological hazard. Elevia 1.1 Salmonella spp. (V-PAT04, RT-qPCR with AiGOR technology) has an AOAC certification scope with low-moisture matrices such as 62% cocoa chocolate, cocoa liquor, skimmed milk powder and peanuts, and TAAG also validated it in filled chocolates, hazelnut and cocoa cream, animal feed pellets and stainless steel surfaces, with a declared sensitivity of 1 CFU/375 g in foods. Specio 1.1 Salmonella spp. (V-SF31, real-time PCR with melting curve) declares foods, beverages and living and inert surfaces in general. Neither has spices among its validated matrices: the scope for spices or seasonings must be confirmed with TAAG. To choose by industry and matrix, see how to choose a TAAG kit.
Conclusion
Ground spices and herbs combine the conditions for fraud: high value, long chains and a product that cannot be recognized with the naked eye. The European coordinated plan showed that the problem is real, especially in oregano, and that it ranges from bulking with other plants to unauthorized dyes and, in isolated cases, lead chromate. No single method is enough: microscopy, infrared, LC-MS and DNA answer different questions and complement each other. Because fraud can introduce allergens, toxic substances and a less controlled chain with respect to Salmonella, spice suppliers should be assessed for authenticity and for safety at the same time.
About TAAG
Ask TAAG about the scope of Elevia 1.1 Salmonella spp. and Specio 1.1 Salmonella spp. for your spices and seasonings before adding them to your verification plan.
Frequently asked questions
Which spice was the most adulterated in the European control?
Oregano. In the EU coordinated plan analyzed by the JRC, 48% of the 295 samples were suspected of adulteration, in most cases with olive leaves. It was followed by pepper (17%), cumin (14%), turmeric and saffron (11% each) and paprika/chilli (6%).
Why is lead chromate added to turmeric?
To give the root a brighter yellow and sell it better. It is an industrial pigment that contributes lead, a neurotoxicant. Studies in Bangladesh documented the practice in polishing mills, and in 2021 the EU set a limit of 1.50 mg/kg of lead for root and rhizome spices, expressly citing this fraud among its reasons.
Which method can detect adulterated oregano?
It depends on the question. FTIR or NIR serve as rapid screening; LC-MS confirms markers such as olive oleuropein; and DNA methods (real-time PCR, digital PCR or metabarcoding) identify which plant species are present even when the product is ground. The JRC combined several techniques before declaring a sample suspicious.
Is spice fraud only an economic problem?
No. The added material may be an undeclared allergen, such as mustard or gluten-containing cereals, and some dyes and pigments (Sudan, lead chromate) are toxic. In addition, a supply chain with uncontrolled handling is also more vulnerable to hazards such as Salmonella.
How common is Salmonella in spices?
FDA estimated a mean prevalence of 6.6% in imported spice shipments to the U.S. between 2007 and 2009, 1.9 times that of other regulated foods it sampled. At retail, prevalence was lower in 9 of 11 types of spices, which the agency attributes to pathogen reduction treatments applied after import.