Vol. 12, Issue 12 (2023)

Author(s):
Ravina Parmar, Brijesh Khanpara, Nirav Joshi and Mukesh Dabhi

Abstract:
Blanching and drying are two major post-harvest operations which influence the quality characteristics of turmeric (Curcuma longa). The objective of this study was to find the effect of four different blanching times (15, 30, 45 and 60 min) and tray drying of turmeric rhizomes (var. Salem) at three different drying temperatures (60, 70 and 80 ℃) by forced air circulation. It was found that the blanching time and drying temperature significantly affected the drying time of the turmeric rhizomes. The drying process of turmeric rhizomes occurred in a falling rate period. The mathematical modelling was analysed for all twelve treatment combinations by fitting the different mathematical models based on the drying coefficient (k), root mean square error (RMSE), coefficient of regression (R²) and the sum of chi-square (χ²). The non-linear regression analysis was carried out on the experimental data of moisture ratio and drying time. The turmeric rhizomes blanched at 60 min and dried at 80 ℃ had the highest drying coefficient and the lowest drying time. The drying time of turmeric rhizomes was decreased with the increase in blanching time and drying temperature. The effective diffusivity increased as the blanching time and drying temperature increased. The effective moisture diffusivity varied from 4.68×10^-9 to 14.77×10^-9 m²/s. The activation energy of turmeric rhizome was also found to increase with an increase in the blanching time. For the goodness of fit, the best suitable model for the dried turmeric rhizomes was found to be the Midilli model with the highest regression coefficient and the lowest root mean square error.