Color degradation of lemon balm (Melissa officinalis L.) as affected by the drying process
- Publication Type
- Contribution to conference
- Authors
- Argyropoulos D, Kudadam J, Müller J
- Year of publication
- 2009
- Published in
- Proceedings of the 5th CIGR International Technical Symposium
- Page (from - to)
- 730-763
- Conference name
- 5th CIGR VI Session International Symposium on Food Processing, Monitoring Technology in Bioprocesses and Food Quality Management
- Conference location
- Potsdam (Germany)
- Conference date
- 31.08.-02.09.2009
The effect of the conditions of drying air on the color of Melissa officinalis L. leaves was investigated in this research. The drying experiments were conducted in a through flow laboratory dryer at air temperatures ranging from 30 to 70 °C and corresponding relative humidity (10 g/kg absolute humidity). Additional trials were carried out at 15, 20, 25 and 30 g/kg absolute humidity maintaining a temperature of 40 °C to investigate t he effect of increased humidity of the air. The air velocity was set constant at 0.2 m/s. The color of the leaves was measured by a CR-400 Minolta reflectance colorimeter. The individual color parameters were expressed as L* a* b* and converted into L* C* h° color scale. One-way analysis of vari ance (ANOVA) was performed using SAS statistical package. Hue, expressed as h° value pro ved to be the appraisal criterion for the color quality of lemon balm since it depicts the visual impression of browning effectively. Drying air temperature showed significant effect on the color of the leaves. Samples dried at 30 and 40 °C appeared greener in color indicating the highest h° values, 110 and 102 degrees respectively. Considerable color degradation was observed at temperatures above 50 °C. The effect of relative humidity on the color was insignificant below 40 %, however, a gradual decrease of the h° value from 104 to 98 degrees was documented for an increase in relative humidity from 40 to 50 %.