Evaluation of Quality Characteristics of Potato Slices during Drying by Infrared Radiation Heating Method under Vacuum

Abstract

The effect of drying behaviour on the drying rate and quality characteristics of potato slices in a vacuum- infrared drying system was studied. In this work, the effect of the infrared radiation powers (100, 150, and 200 W) and vacuum levels (20, 80, 140 mmHg and atmosphere pressure) at different slice thickness (1, 2 and 3 mm) on drying rate and shrinkage percentage and rehydration capacity were investigated. From the study, it was concluded that IR power level has a significant effect on processing time and drying rate. With increasing radiation power, time drying is reduced and consequently drying rate is increased. The drying rate curve of potato slices at initial drying time is in the ascending phase because of surface moisture evaporation and after this phase due to the start of influence of water from within of material to surface descending phase occurs. Also, shrinkage percentage increased with increase of sample thickness. In other words, shrinkage was decreased at different thickness with an increase of infrared radiation power and vacuum level. It was discovered that the long period of drying and increase of sample thickness may have contributed to a decrease in rehydration capacity. Because of porous texture of potato, as soon put in boiling water for 3 minutes, the water absorption process quickly started and before the insert damage to product tissues, to maximum amount of water absorption will reach. The results also showed that with increasing shrinkage, rehydration capacity was decreased.