Work came after FSA referred sample and cumin testing

Testing method confirms almond in paprika, not mahaleb

By Joseph James Whitworth

- Last updated on GMT

The referred sample contained Prunus protein(s) and DNA the origin of which is consistent with almond and not mahaleb
The referred sample contained Prunus protein(s) and DNA the origin of which is consistent with almond and not mahaleb

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DNA testing and mass spectrometry have been used to confirm almond in paprika and not mahaleb which was found in cumin as part of earlier nut and spice-related recalls.

A sample of paprika was referred to the Government Chemist by the Food Standards Agency (FSA) to see if it was possible whether almond or mahaleb or both were present.

This required further investigation of the analytical methods developed for cumin to ensure they were applicable in paprika.

Variety of techniques used

The Government Chemist team, in addition to ELISA, applied DNA, with a PCR test for mahaleb and a screening PCR for selected common Prunus species, as well as mass spectrometry techniques to complement and confirm results.

Earlier this year, the FSA backtracked on a recall of Bart Ingredients’ ground cumin​ because of almond after additional testing found it was mahaleb and not almond protein present.

However, the agency said at the time recalls for undeclared almond in paprika products would stand.

Michael Walker, consultant referee analyst, said after the Government Chemist team had completed the cumin investigation it was asked to look at a sample of paprika.

“In the sample of paprika we found strong evidence of almond and no evidence of mahaleb,” ​he told FoodQualityNews.

"We always caveat this by saying that more needs to be known about the hundreds of Prunus species because another (as yet uninvestigated) species may cross react.

“But we have checked almond, apricot, and peach and are confident these do not cross react with our mahaleb test. We also checked that peanut does not cross react with our mahaleb test but as far as we know the presence of peanut in spices was an issue in North America rather than the UK.”

Evidence of almond, not of mahaleb

Almond is a member of the genus ‘Prunus’ - trees and shrubs, which includes the plums, cherries, peaches, nectarines, apricots and mahaleb. Prunus mahaleb, previously little known in the UK, was responsible for false positive results for almond in cumin.

ELISA, the most commonly applied technique for the detection of food allergens, reacts to several common Prunus species, as do some PCR DNA assays.

LGC scientists applied ELISA and DNA and mass spectrometry techniques and confirmed the referred sample contains Prunus species proteins.

Specially developed DNA tests showed that mahaleb DNA was not present but a profile for the sample consistent with the presence of almond DNA was found. This was confirmed by chromatographic and mass spectrometric data.

Although limitations still remain in the science, the referred sample contains Prunus protein(s) and DNA the origin of which is consistent with almond rather than mahaleb.

Walker said the work has shown the methods can be successfully applied to cumin and paprika, which is cause for hope that they can be transferred to any food matrix.

“However it is always necessary to validate a method in the particular food tested to check for problems including interferences, cross reactivity, extraction problems or signal suppression,” ​he said.

“My advice is of a general nature – know and verify your supply chain, and apply GMP. ELISA remains a good general screen, so carry out a risk assessment on any positive result.

“Any positive result should be followed up by a risk assessment on a case by case basis. Testing is only a part of Good Manufacturing Practice which is a safeguard against both false positives and false negatives.”

Allergic reaction potential

When asked if the levels being referred to were enough to provoke an allergic reaction, Walker said there is no published allergen reference dose for almond.

“However it is probably reasonable to expect that such a dose would be of the same order of magnitude as that for hazelnut (0.1 milligram of the protein),” ​he said.

“On that basis and given that paprika is included in food at 1–2 % and if the almond is distributed evenly the levels we have seen should not be a problem for most of the almond allergic population.

"A problem could exist for an individual who is particularly sensitive to almond encountering a ‘hot spot’ of almond where there is a patchy distribution of almond in the paprika.

“There is no published information on the allergenicity of mahaleb but given the similarities in composition that cause the analytical difficulties it is in my view proper to take a precautionary approach and assume an almond allergic individual could react to mahaleb.

“The severity of such a reaction is a completely unknown issue.”

When asked about confidence in ELISA techniques, given it prompted a false positive in Canada​, Walker said ELISA, the only currently widely available testing method for almond, is a good screening technique which will pick up Prunus species (almond or mahaleb, or apricot), so in that sense it has received a ‘vote of confidence’.

Walker said it is aiming to transfer the methods to the market through publication (and/or application notes on the Government Chemist website). The take-up by commercial providers will then depend on market demand.

Details of the methods are being written up for publication which is anticipated by early 2016. 

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