Effect of Convective Drying and Far-Infrared Radiation on the Physical Properties and Microstructure of Yacón Chips (Smallanthus sonchifolius)

Abstract

Convective drying is widely used in the food industry due to its simplicity and versatility, as it allows for better temperature control and heat distribution, which is essential for maintaining product quality. However, this method can be slower compared to infrared drying. The aim of this research was to evaluate the effect of convective and infrared drying on the physical properties and microstructure of yacón chips. An infrared dryer and a convection dryer were used to this effect, setting temperatures of 60, 70, and 80 °C for both methods. The color and texture properties, as well as the microstructure, changed with the increase in temperature. The greatest color variation in the yacón samples was reported by infrared drying at a temperature of 80 ° C. Regarding texture, there were no differences between the two methods. The microstructure of the yacón samples dried by hot air exhibited more significant cell damage, especially at 60 °C, in comparison with infrared drying, which showed a more microporous and compact structure. The results indicate that the method used impacted shrinkage: infrared drying produced a higher level of shrinkage when compared to convective drying. It is important to note that this is a significant physical change that can adversely affect the quality of dehydrated food. Infrared drying produced greater rehydration in comparison with convective drying. Similarly, improved rehydration was observed at a temperature of 70 ºC. In conclusion, the infrared drying method, coupled with appropriate drying conditions, constitutes a good alternative for drying yacón chips.