Thermal degradation of cyanidin-3-O-glucoside: Mechanism and toxicity of products.

• The thermal degradation of Cy3G in nitrogen over 30–600 °C occurs in three steps. • The phenols and furans in the pyrolysis products of Cy3G are toxic to some extent. • For safety, anthocyanin-rich foods should be processed at below 100 °C. • High-temperature processing of anthocyanin-rich foods produces toxic substances. The thermal degradation behavior of cyanidin-3-O-gluoside (Cy3G) in nitrogen and air was studied using thermogravimetric analysis (TGA), thermogravimetry–Fourier transform infrared spectroscopy (TG-FTIR) and pyrolysis–gas chromatography/mass spectrometry (Py-GCMS). The results show that the thermal degradation of Cy3G in nitrogen and in air can be divided into three steps. The total degradation rate was 63.09% in nitrogen and 99.42% in air, and the total activation energy (E a) was 65.85 and 80.98 kJ·mol−1, respectively. The TG-FTIR analysis showed that Cy3G is significantly decomposed at 200–300 °C. The Py-GCMS analysis shows that the first step in the thermal degradation of Cy3G in nitrogen is the cleavage of glycosidic bonds to give cyanidin and glucoside. The glucoside and cyanidin then degrade further to give mainly low molecular weight compounds, together with furan derivatives, pyran derivatives and aromatic compounds. The phenols and furans found in the pyrolysis products are known to have a degree of toxicity. [ABSTRACT FROM AUTHOR]