Thermal characterization of the anthocyanins from black soybean (Glycine max L.) exposed to thermogravimetry

- Anthocyanins of black soybean seed coat were identified.
- The thermal characterization of anthocyanin was studied by thermogravimetry analysis.
- Thermodynamic analysis was applied by free dynamic model.
- TG-isothermal experiments confirm the accuracy of the thermodynamic analysis.

One anthocyanin compound, cyanin-3-glucoside, was isolated and identified by high performance liquid chromatography tandem mass spectrometry (HPLC_MS/MS) from seed coat of black soybean variety, Heizi to assess its thermal characterization in vitro. The thermal characterization of anthocyanin was studied by thermogravimetry (TG) analysis. The results from the TG curves showed the decomposition of anthocyanin occurred in three stages. Glucose cleaved from the cyanin-3-glucoside occurred in the first stage. Degradation of cyanin and small amounts of cyanin-3-glucoside appeared mainly in the second stage. The sugar in the anthocyanin was decomposed in the third stage. Thermodynamic analysis was applied by free dynamic model. TG-isothermal experiments for the anthocyanins from black soybean seed coats confirmed the correct of the thermodynamic analysis.