Effect of Hot Water Blanching Time and Drying Temperature on the Thin Layer Drying Kinetics of
and Anthocyanin Degradation in Black Carrot (Daucus carota L.) Shreds

Umar Garba1,2, Sawinder Kaur1*, Sushma Gurumayum3 and Prasad Rasane1

1Department of Food Technology and Nutrition, School of Agriculture, Lovely Professional University, Phagwara, 144402
 Punjab, India
2Department of Agricultural Bioengineering Technology, Audu Bako College of Agriculture, Dambatt a, Kano State, Nigeria
3Department of Microbiology and Bioprocess Engineering, School of Biotechnology, Lovely Professional University, Phagwara,
 144402 Punjab, India

Article history:
Received July 25, 2014
Accepted April 21, 2015

Key words:
black carrot, blanching, effective diffusivity, activation energy, drying rate, thin layer model, anthocyanin content

This study was conducted to investigate the effect of blanching treatment (98 °C for 3 and 6 min) and air drying temperature of 40, 50 and 60 °C on the thin layer drying characteristics such as drying time, drying rate constant, effective moisture diffusivity and activation energy, as well as on anthocyanin content of black carrot shreds. It was observed that drying temperature affected the drying rate but blanching did not have an effect on drying time. Three thin layer drying models, i.e. Page, Lewis and Henderson-Pabis were evaluated. The goodness of these models was evaluated based on the coefficient of determination (R2), root mean square error, reduced chi square (χ2) and standard error. Page model showed the best fit to the drying data. The effective diffusivity ranges of 1.4·10–9 to 2.6·10–9 m2/s, 1.3·10–9 to 2.1·10–9 m2/s and 1.5·10–9 to 2.2·10–9 m2/s after 3 or 6 min of blanching and control samples respectively were calculated using Fick’s second law. The activation energy of 37.5, 26.0 and 34.6 kJ/(mol·K) of the control samples and samples blanched for 3 or 6 min respectively was determined from the Arrhenius plot. The blanching treatment affected the anthocyanin content to a great extent. The anthocyanin content of (231.7±2.9) and (278.8±7.8) mg per 100 g was recorded in samples blanched for 3 and 6 min and then dried at 60 °C, and (153.0±4.3) and (247.0±5.5) mg per 100 g was recorded at 40 °C as compared to the control of (580.1±1.3) at 60 °C and (466.7±1.1) mg per 100 g at 40 °C.

*Corresponding author:  email3  This email address is being protected from spambots. You need JavaScript enabled to view it., This email address is being protected from spambots. You need JavaScript enabled to view it.
                                      tel3  +91 9815 151 541