Thermal stability of 3-deoxyanthocyanidin pigments

Abstract

3-Deoxyanthocyanidins are promising natural colourants due to their unique properties compared to anthocyanins. However, thermal stability of 3-deoxyanthocyanidins is largely unknown. Thermal stability of crude and pure 3-deoxyanthocyanidins was determined at 95 °C/2 h and 121 °C/30 min, at pH 1-7 using HCl, formic or citric acid as acidulants. The colour retention of crude and pure 3-deoxyanthocyanidins (79-89% after 95 °C/2 h and 39-118% after 121 °C/30 min) was high compared to literature reports for anthocyanins under similar treatments. pH significantly affected the thermal stability of 3-deoxyanthocyanidins: Colour retention was better at pH 1-2 (70.2-118%) than at pH 3-7 (39.0-86.8%). Chalcones were identified as the major heat degradation products at pH 3-7. Slow rate of chalcone formation and resistance to C-ring fission were identified as the major contributors to thermal stability of 3-deoxyanthocyanidins. Overall, the heat stability of 3-deoxyanthocyanidins indicates good potential for food use.

Keywords: 3-Deoxyanthocyanidins; Anthocyanins; Heat stability; Natural colour.