LC–HRMS and Magnetic Traps Detect Patulin in Apple Juice

Patulin is a toxic substance produced by mold that is often found in apple products and can pose serious health risks to consumers. With food safety rules becoming stricter and patulin being difficult to test for, researchers at the University of Murcia in Spain have developed a new way to prepare apple juice samples for testing. Their approach uses tiny magnetic particles designed to grab patulin and the substances it breaks down into, which can then be pulled out of the juice with a magnet. The captured compounds are then identified and measured using liquid chromatography-high resolution mass spectrometry (LC–HRMS). A paper based on their research was published in the journal Analytical Methods.¹

What Are Magnetic Molecular Traps, and Why Use Them to Detect Patulin?

Combining tiny magnetic particles with specially designed "molecular trap" materials has led to a new type of material that works like a magnetic trap. These are usually built like a coated ball: the center is made of magnetic particles, and the outer layer is a plastic-like coating containing custom-shaped pockets that fit a specific target molecule, much like a lock and key. This design brings together the best of both materials. The custom pockets make the trap highly selective, grabbing only the molecule it's designed for, while the magnetic core makes it easy to pull the trapped molecules out of complicated mixtures, such as fruit juice, simply by using a magnet.²

One especially promising use for these magnetic traps is capturing patulin, a toxic compound made by several types of molds, most commonly Penicillium expansum, the mold responsible for rotting apples.²The International Agency for Research on Cancer says there is not enough evidence to determine whether patulin causes cancer in humans. However, the World Health Organization considers it a substance that can damage DNA.3 Because patulin may be harmful to health, the European Food Safety Authority has set safety limits for it, recommending that people consume no more than 0.4 micrograms per kilogram of body weight each day.⁴

^“Given the toxicological relevance of patulin and its regulatory limits in apple-based products,” write the authors of the paper,¹ “the development of highly selective extraction techniques is essential for accurate quantification and enhanced food safety.”

How Well Did the New Method Detect Patulin in Apple Juice?

The researchers took a commercially available molecularly imprinted polymer designed to capture patulin specifically and made it magnetic, creating a tool that grabs patulin very selectively and is easy to handle. Using microscopes and other analytical tools, they confirmed that the material had become magnetic and had the right structure. The method gave reliable, proportional readings across a wide range of concentrations and could detect very small amounts of patulin, well below the maximum levels allowed under European law. Tests also showed it was both accurate and consistent. When the team tested ten apple juices bought from stores, they found patulin in one of them, at a low level. Further analysis also suggested that two substances patulin breaks down into, hydroascladiol and ascladiol, were likely present in three of the juices.¹

"The proposed magnetic molecularly imprinted polymer-based workflow," write the authors of the paper,¹ "represents a significant advancement for both regulatory monitoring and broader mycotoxin derivative screening." They add that routine food safety testing should not only detect patulin sensitively but also look for the substances it breaks down into.¹

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References

1. García-Nicolás, M.; Jiménez-López, A.; Arroyo-Manzanares, N. et al. Magnetic Molecularly Imprinted Polymer for Selective Extraction and Untargeted Monitoring of Patulin and its Metabolites in Apple Juices by UHPLC-HRMS. Anal Methods 2026.DOI: 10.1039/d6ay01494a
2. Notardonato, I.; Gianfagna, S.; Castoria, R. et al. Critical Review of the Analytical Methods for Determining the Mycotoxin Patulin in Food Matrices. Rev. Anal. Chem. 2021, 40 (1), 144-160. DOI: 10.1515/revac-2021-0131
3. Saleh, I.; Goktepe, I. The Characteristics, Occurrence, and Toxicological Effects of Patulin. Food Chem Toxicol. 2019, 129, 301-311. DOI: 10.1016/j.fct.2019.04.036
4. Fürst, P.; Milana, M. R.; Pfaff, K. et al. Risk Evaluation of Chemical Contaminants in Food in the Context of RASFF Notifications: Rapid Assessment of Contaminant Exposure tool (RACE). EFSA Support. Publ. 2019, 16 (5), 1625E. DOI: 10.2903/sp.efsa.2019.EN-1625