Banana Chip Drying Using Far Infrared-Assisted Heat Pump
Banana chips were dried using a heat pump (HP) dryer alone or in combination with far infrared radiation (FIR) at 500, 1000 and 2000 W (500 FIR, 1000 FIR and 2000 FIR, respectively). The experimental results were presented in terms of the drying characteristics and the qualities of the dried product in terms of shrinkage, color, texture, percentage of rehydration and moisture content. From an initial moisture content of about 76% (w.b.), the samples were dried to a final moisture content of <17% (w.b.) at a drying temperature of 40 °C and at an air flow rate of 0.8 m sˉ¹ in all the experiments. FIR + HP drying increased the drying rate by reducing the drying time, resulting in dried banana chips with generally higher values of lightness and comparable values of redness and yellowness compared with the HP-treated samples. With HP + 1000 FIR, the dried banana chips had lower shrinkage values, improved rehydration ability, lower hardness values and higher brittleness values compared with those dried by using HP, HP + 500 FIR and HP + 2000 FIR. Notably, the total energy used for the FIR-assisted drying processes decreased as FIR intensity increased. The results suggest that the best dried product can be obtained by use of HP + 1000 FIR and that HP + FIR drying is an effective and economical method for drying banana chips.
Key Words: banana chips, far infrared radiation, heat pump