Effect of blanching on drying kinetics of quince pomace undergoing conventional hot air and low-pressure superheated steam drying

Abstract

The process of extracting fruit pectin includes the drying of pomace to prevent enzymatic destruction. It is known that best quality pectin is obtained from pomace dried at low temperature. Moreover, blanching and reduction in oxygen content as that condition obtained by low-pressure superheated steam drying (LPSSD), reduce pectin color. Last improve is obtained by inhibition of enzymatic reactions. The main objective of this work was to determine the effect of blanching on drying kinetics of quince pomace undergoing conventional hot air and LPSSD drying, a method recognized as less aggressive. Quince pomace drying was conducted to final to initial water content ratio (X/X o)< 0.07, where X is the water content. Drying curves were fitted to Page model. Results show statistical differences between drying methods; however, differences in kinetics were not found among treatments (blanching or not). As a conclusion, blanching of quince pomace did not affected drying kinetics, and both assayed methods of drying (conventional and LPSSD) required the same time to reach the same final water content. Therefore, pomace drying method should be selected by preferentially considering pectin quality and energy consumption.