THE EFFECT OF CONVECTIVE AND MICROWAVE DRYING ON THE TEXTURAL PROPERTIES OF ONION SLICES

Abstract

The effect of convective and microwave drying on the textural characteristics of onion slices of varying thickness (3 and 7 mm) with and without pretreatment was studied. Immersion in an 8% NaCl solution was used as pretreatment. Drying was carried out at temperatures of 50, 60, and 70 °C (convective) and at powers of 68, 204, and 340 W (microwave). Texture parameters were determined using profilometric analysis: hardness, chewiness, springiness, and adhesiveness. It was found that an increase in temperature or microwave power leads to an increase in the hardness and chewiness of the samples, with microwave drying providing higher values for these parameters compared to convective drying. Pretreatment in brine increases hardness and chewiness during convective drying, but decreases these parameters during microwave drying. Slice thickness significantly affects springiness, increasing it at greater thicknesses. Empirical models with high coefficients of determination have been developed to describe the dependence of textural properties on process parameters. The results obtained can be used to optimize vegetable drying processes to preserve quality and consumer properties.