RSSL offers tests for adulterated oregano

By Rick Pendrous contact

- Last updated on GMT

A Which? survey has picked up widespread adulteration of dried oregano
A Which? survey has picked up widespread adulteration of dried oregano

Related tags: European union, Food safety

A new service for verifying the authenticity of dried oregano has been launched, following news of high instances of adulteration of the herb on sale in the UK.

Reading Scientific Services (RSSL) has introduced two levels of testing as research​ commissioned by consumer group Which? showed that a quarter of samples of dried oregano tested contained other ingredients.

The oregano research, carried out by Professor Chris Elliott director of the Institute for Global Food Security at Queen’s University Belfast, revealed that other ingredients were found to make up between 30% and 70% of the products tested.


RSSL’s first test involves microscopy, which is suitable for detecting significant levels of adulteration. This detection capability is sufficient to detect adulteration at the 30–70% levels, said RSSL.

While lower levels of adulteration might also be detected by microscopy, the turnaround time for this would be more than the five days offered for a routine assessment. Consequently, the second test method offered by RSSL is analysis by gas chromatography-mass spectrometry (GC-MS).

This method compares the volatile chemical profile of a trusted sample of pure oregano with those of the test samples, allowing chemists to detect any obvious differences between the two. Any such differences will be indicative of cross contamination or adulteration.

“As with any techniques for identifying authenticity there are limitations and a positive result does not necessarily imply deliberate adulteration,”​ said Karen Masters, commercial operations manager at RSSL.

“However, the immediate concern is to eradicate the instances of gross contamination that the Which? report exposed, and our methods are capable of identifying contamination or adulteration at the levels reported.”

In addition to the services offered by RSSL, other companies, such as Genon Laboratories, are offering advanced genetic sequencing tests, which permit the detection of large numbers of different animal and plant species on food samples.

Arsenic in rice

Meanwhile, following the publication last June of EU Regulation (EU) 2015/1006 amending the annex to Regulation (EC) No 1881/2006 regarding maximum levels of inorganic arsenic – a toxic carcinogen – in foodstuffs, such as rice and rice-based products, inspection company SGS has drawn manufacturers’ attention to what the changes will mean for them.

As rice is an important ingredient in a variety of food for infants and young children, SGS which carries out contamination testing, pointed out that the maximum levels of arsenic should be set for rice and rice-based as follows:

  • Non-parboiled milled rice (polished or white rice) 0.20mg/kg
  • Parboiled rice and husked rice 0.25mg/kg
  • Rice waffles, rice wafers, rice crackers and rice cakes 0.30mg/kg
  • Rice destined for the production of food for infants and young children 0.10 mg/kg

EU Member States and food business operators have until January 1 2016 to adapt the new maximum levels of arsenic before the new rules relating to this regulation come into force.

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