COMPARATIVE EFFECTS OF THREE DIFFERENT DRYING METHODS ON DRYING KINETICS AND QUALITY OF JERUSALEM ARTICHOKE (HELIANTHUS TUBEROSUS L.)

摘要

Mid-infrared-assisted freeze drying (MIR-FD) of Jerusalem artichoke cubes were attempted and their performance (processing time, energy consumption, color, water activity, hardness and rehydration) was compared with single-stage freeze dried (FD, control) samples. Two mathematical models could be used to describe the drying curves. It was aimed to improve the drying parameters and product quality of MIR-FD dried material. The effect of mid-infrared pre-drying (MIR) on drying rates of Jerusalem artichoke cubes was examined at different infrared intensity (3 and 6 kW/m22). The values of drying rate considerably changed when the infrared intensity and pre-drying time was increased from 3 to 6 kW/m22 and from 4 to 5 min. The MIR-FD hybrid drying mode took 15-40% lesser time compared to FD dried samples. Therefore, MIR-FD drying is an effective and economical method. MIR application had a significant (P<0.05) effect on the color of the final product. The FD resulted in a product with significantly lower firmness and slightly higher water uptake (P<0.05) than samples dried in the MIR-FD. Hybrid drying gave better results - all of the quality parameters - over MIR alone.