Results from the Laboratory of the Government Chemist (LGC) showed mahaleb was present and not almond protein.
Bart Ingredients requested a referee analysis earlier this year after the recall due to allergen concerns at the end of January.
It said mahaleb, a spice made from the seeds inside a species of cherry stone, gave a positive reading for almond using polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA).
We were confident of our controls - Bart Ingredients
Greg Corbishley, head of technical at Bart Ingredients, said it was delighted at the rescindment of the recall.
“From the outset we were confident of our controls and those of our growers and processors," he told FoodQualityNews.
"Consumer safety is always our primary focus and our team here at Bart Ingredients has worked tirelessly, in full cooperation with the FSA, throughout what has been a very detailed investigation.
"We have been fully involved in helping with the review of the complex and detailed scientific analysis required to prove that our product is free from almond presence.
“We very much regret if this incident has been cause for concern for any of our customers and we are delighted that the integrity of our products has been confirmed."
Mahaleb not almond
Results show the sample contains Prunus protein and DNA, the origin of which is consistent with mahaleb rather than almond, said the Government Chemist.
It added limitations still remain in the science that prevents the presence of almond being completely ruled out.
Mahaleb is not one of the 14 allergens identified in food allergen legislation.
Will Creswell, head of consumer protection at the FSA, said there was no evidence the contamination was a result of fraudulent activity.
“Throughout this incident we have carried out protein and DNA testing, using accredited laboratories and validated methods, and both indicated the presence of almond protein in this product,” he said.
“We were correct to ask Bart Ingredients to take precautionary action. Now that new evidence has come to light we are able to rescind this particular recall.
“The FSA will now work with public analysts, analytical scientists, the industry and local authorities to review these testing methodologies. As with all significant incidents, we will also work together to review our actions and identify what lessons can be learned.”
Scientists looked at routine ELISA tests used previously and applied advanced DNA and mass spectrometry techniques to determine differences in DNA and protein structures that distinguish almond and mahaleb.
Almond is a member of the genus ‘Prunus’ - trees and shrubs, which includes plums, cherries, peaches, nectarines, apricots and mahaleb.
Little was known about Prunus mahaleb previously in the UK but it was said to have been handled in the cumin supply chain.
Prunus species protein was confirmed above the limit of quantification (LOQ) of three ELISA platforms with statistical significance.
Government Chemist DNA test
A specially developed real-time PCR method generated a response consistent with mahaleb DNA.
The significant sequence homology across Prunus species prevented the simultaneous development of a set of DNA assays specific to almond and other common Prunus species, said the Government Chemist.
“However chromatographic and mass spectrometric signals related to almond and/or mahaleb kernels suggest that mahaleb protein is present in the laboratory sample. No peptide occurring solely in almond kernel was detected,” it added.
To resolve the scientific dispute scientists working within the Government Chemist programme developed a DNA test that, along with mass spectrometry, is able to distinguish between almond and mahaleb.
ELISA, the common technique to detect food allergens, reacts to several common Prunus species, as do commercially available PCR DNA assays.
There is no available DNA assay that appears specific to almond only, said the Government Chemist.
Michael Walker, consultant referee analyst, said it now knows ELISA detection is useful but only as a screening test.
“There are unusually high similarities in the DNA and protein of these related species that make it very difficult to tell them apart in spices," he said.
“But thanks to the expertise of the molecular biologists and protein chemists in LGC we have developed what is, to the best of our knowledge, the world’s first DNA test for mahaleb and discovered subtle mass spectrometry differences to distinguish almond and mahaleb proteins.”
FSA said there have been other recalls with the majority being for undeclared almond in paprika products. There is no evidence of cross-reactivity due to mahaleb in paprika. However, it is doing further research to clarify this.
All other recalls associated with almond contamination of paprika still stand as evidence suggests the affected products remain a potential health risk to people with an allergy to almond, added the agency.