Characterization of Dried Kiwi by Infrared Systems and Process Modeling

Modeling might be considered as a relationship between different variables during drying of food products and mass transfer kinetics and moisture diffusivity coefficients can be used as useful tools for the optimal control of the process conditions that improve the quality of the final dried product. Kiwi fruit has favorable taste and aroma and has a high nutritional value. The aim of this research work is to investigate the effect of radiation on the characterization of Kiwi fruit.
In this study the effect of radiation lamp power at three levels of 200, 250 and 300 W, at 5, 10 and 15 cm distance from sample surface on mass transfer kinetics, moisture diffusion coefficients, density, color change, texture and rehydration of the Kiwi were investigated.
The results showed that the lamp power and the distance from the sample surface have significant effect on moisture loss kinetics and drying time. By increasing the infrared lamp power, the weight loss is increased (61.01 %) and by increasing the infrared lamp power from 200 to 300 W, the effective diffusivity coefficient has been increased from 6.25×10 10 m2/s to 13.8×10-10 m2/s. The color of the samples were analyzed by image processing technique and the average color changes (ΔE) for 200, 250 and 300 W were 14.02, 19.09 and 21.66, respectively. The average density and rehydration for dried samples were 743 kg/m3and 229.18 %, respectively.
The effect of infrared power on effective diffusivity coefficient of Kiwi was investigated and found that the effective diffusivity coefficient is increased by increasing the source of heat. The hardness of dried kiwi slices through infrared dryer was in the range of 9.55-11.08 N. In the Kiwi drying process modeling as compared with other models, Page model had the best match with the experimental results.