Effect of pH and temperature on tropane alkaloids within a processing strategy to provide safe infant cereal-based food

Abstract

Tropane alkaloids (TAs) are secondary metabolites from weeds that can contaminate cereals and vegetables during harvest. Due to their toxicity, the Regulation (EC) 2023/915 sets maximum levels for atropine and scopolamine in cereal-based foods for infants containing millet, sorghum, buckwheat or their derived products. The aim of this study was to evaluate the effect of pH and temperature on the stability of TAs, as possible parameters in thermal processing to mitigate this chemical hazard in cereal-based infant food. The effect of pH (4 and 7) and temperature (80 °C and 100 °C) was assessed in buffer solutions. Also, treatment at 180 °C was performed in spiked and naturally incurred millet flour to assess the effect of high temperature, simulating cooking or drying, on the stability of TAs in the cereal matrix. The fate of 24 TAs was assessed by UHPLC-MS/MS. TAs showed high thermostability, although it was variable depending on the specific compound, pH, temperature and treatment time. In buffer solutions, higher degradation was found at 100 °C and pH 7. In spiked millet flour at 180 °C for 10 min, scopolamine and atropine contents decreased by 25 % and 22 %, similarly to other TAs which also showed a slow thermal degradation. Atropine, scopolamine, anisodamine, norscopolamine, scopine and scopoline were found in naturally contaminated millet flour. Interestingly, naturally incurred atropine was more thermostable than when spiked, showing a protective effect of the cereal matrix on TAs degradation. The present results highlight the need for an accurate monitorization of TAs in raw materials, as this chemical hazard may remain in infant cereal-based food even after intense thermal processing.