Effect of hot drying on the essential oil content and colour characteristics of peppermint

  • Nguyễn Thị Yến Chi
  • Dương Thị Thanh Thảo
  • Hoàng Quốc Tuấn


The main objectives of this study were to investigate the effect of different temperature of hot air drying on the qualities of dried peppermint, including essential oil content, colour parameters, and visual sensory quality and to develop mathematical models for the colour change kinetics. The drying experiments were carried out at five air temperatures, 40, 50, 60 70 and 80 ‘’c. The colour parameters for colour change of the materials were quantified by the Hunteri (whiteness/darkness), a (redness/greenness) and b (yellowness/blueness) system. These values were also used for calculation of total change (AE) as well as chroma, hue angle and Browning index, A consumer preference test was conducted with 80 consumers to as^ss the colour quality of 05 dried peppermint samples. The results showed that the decrease in essential oils content at high drying temperature is higher than at low temperature. Least Squares regression was used to determine the relationship between the visual sensory scores of consumer taster and the Hunter Lab values It was observed that L, a, AE and hue angle values were fitted to the zero-order model, while b and chroma were fitted to the first-order model