New analytical strategies to control food safety

Writing / Irene Vega

The number of food alerts reported on the RASFF portal (Food and Feed Safety Alerts) on the presence of pyrrolizidine alkaloids (PAs) in different food products has increased significantly in recent years. As a consequence of the high levels found of these natural toxins, the EFSA (European Food Safety Authority) has considered its presence as an important Food Safety problem.

The relevance of this topic has recently been highlighted in a published review paper by the GQAA-MAF of the URJC in the scientific journal Trends in Food Science & Technology. “PAs are secondary metabolites of plants produced as a defense mechanism against herbivores and insects. To date, more than 600 different structures of these toxins have been described and they have been identified from more than 6.000 plant species that belong to the families Asteraceae, Fabaceae, Boraginaceae, Orchidaceae and Apocynaceae”, points out Dr. Isabel Sierra , responsible for the study and director of the group GQAA-MAF.

The ingestion of PAs has been associated with liver damage and some of them are mutagenic and carcinogenic. "The problem occurs when these toxins contaminate products intended for human consumption, such as spices and aromatic herbs," says Dr. Sierra. "This is fundamentally due to cross-contamination caused by the growth of these PA-producing plants as weeds in the fields, although fraudulent practices in this type of product cannot be ruled out."

New strategies in sample preparation

Within the framework of the EVALKALIM project (RTI2018-094558-B-I00), the GQAA-MAF research team proposes the miniaturization and modification of the QuEChERS methodology (Quick, Easy, Cheap, Effective, Rugged & Safe), using a chemically modified large pore size mesostructured silica as adsorbent material for the purification stage. This strategy has been applied to the multicomponent determination of 21 of the natural toxins PAs by means of ultra high performance liquid chromatography coupled to mass spectrometry (UHPLC-MS/MS). "The procedure was miniaturized by reducing the amounts of sample (0,2 g), solvents (2 ml) and adsorbents (25 mg of silica) used, achieving better results compared to other conventional adsorbents" explains Dr. Sierra.

The method was validated and applied to the analysis of 17 commercial samples. The results indicated that all the samples were contaminated with PAs. Thyme and basil samples were the most contaminated, while rosemary were the least. The results of this work have been recently published in the scientific journal Food Chemistry.