Effects of pretreatment and drying methods on molecular structure,functional properties and thermal stability of fibre powder exhibiting colour from Centella asiatica L.

Effects of pretreatment and drying methods and particle size on characteristics of fibre powder from Centella asiatica L. leaves were investigated. Thermal stability of oil‐based colour solutions was also assessed. Steaming and combined steaming and alkaline soaking resulted in the powder with more greenness and higher chlorophylls contents, while combined steaming and acid soaking yielded dark yellow powder with lower chlorophylls contents. Chemical soaking led to the powder with decreased water holding capacity and solubility. Vacuum‐drying reduced chlorophylls degradation, hence retention of the greenness of the powder. Increased particle size resulted in decreased lightness of the powder, but in increased lightness of the solutions; water and oil holding capacities of the powder increased with the particle size. Fourier transform infrared (FTIR) spectra and X‐ray diffraction (XRD) patterns of the powder corresponded to its colour and functional property changes. Colour of the solutions changed only slightly upon heating at 80 and 180 °C for 1 h.