Effect of blanching times and drying temperatures on the color, moisture migrations, microstructures, phytochemicals, and flavors of chili pepper (Capsicum annuum L.)

Abstract

This study investigated the effects of blanching pretreatment (blanched at 100 °C water for 0, 1, 2, 3, 4, and 5 min respectively, and then dried at 60 °C) before hot air drying (HAD) and drying temperature (dried at 55, 60, 65 °C after blanching) on the moisture migrations, microstructures, phytochemicals, and volatile compounds of chili pepper. Overall, the blanching and high temperature could facilitate the removal of water, preserve surface color, alter cell structure and reduce the loss of capsaicinoids in peppers. Blanching pretreatment can promote drying and enhance the effusion of capsaicinoids in peppers by altering cell structure and intervening in water migration. Gas chromatography-ion mobility spectroscopy (GC-IMS) analyses found that aldehydes, ketones and esters contributed to the aroma of dried peppers. The most influenced VOCs of chili pepper by blanching for 1–5 min were volatile alcohols, and the most influenced VOCs of chili pepper by drying at 55–65 °C were Maillard products including ketones, furans and pyrazines. In addition, the chili peppers with various treatments displayed distinct colors, textures, phytochemicals and volatile profiles during dehydration.