Solar biomass hybrid drying and quality evaluation of Eryngium foetidum in an innovative newly developed solar dryer

Abstract

A novel solar-biomass powered hybrid drying system has been developed for studying the drying kinetics, and quality of long coriander (Eryngium foetidum), a medicinal spice. The experiments were carried out in biomass and hybrid energy modes. The findings of each method were compared with open sun drying. Freshly procured leaves of Eryngium foetidum with initial moisture content of 85.15 % (wet basis) was reduced to 9.5 % (wet basis). The biomass and hybrid drying system took 5 h and 8 h to obtain required final moisture. Non– linear regression method was implemented in this study for determining the drying behaviour of Eryngium foetidum. Seven empirical models were selected for determining the drying behaviour of Eryngium foetidum. Medilli model showed the highest R2 and lowest RMSE, χ2 values for both biomass mode (0.9945, 0.02748, 0.00055) as well as hybrid mode (0.9975, 0.01952, 0.00043) respectively. The overall drying efficiency was found out to be 31 % during hybrid mode and 24.22 % during biomass mode of drying. Quality analysis was performed on the final dried product through colour analysis and microbial testing. The colour retention was found out to be better in hybrid mode compared to biomass mode. Microbial analysis revealed that the total plate counts were within permissible limit. There was no growth of yeast and mould observed in both hybrid and biomass mode.