Color retention of red peppers by chemical pretreatments during greenhouse and open sun drying

The color of Paprika, which is one of the most important quality measured, is drastically affected by the drying process of red peppers. This study aimed to measure ability of three different chemical solutions ((I) 2% ethyl oleate, (II) 2% ethyl oleate + 2% NaOH, (III) 2% ethyl oleate + 2% NaOH + 4% potassium carbonate in w/v) on the color retention of dehydrated red peppers in associated with dipping temperature (23 °C and 60 °C) and drying method (greenhouse drying and open sun drying). The surface color was measured by a reflection colorimeter.All pretreatments significantly accelerated drying process. But their effects diminished towards the end of drying since the length of drying time is considerably long. However, their effects on the final color of dried red peppers are more remarkable. Red peppers dipped in ethyl oleate solution and non-pretreated red peppers (the controls) experienced severe color change to blackish color. Dipping red peppers in the solution of 2% ethyl oleate + 2% NaOH + 4% K2CO3 at 60 °C dipping temperature resulted in the best color retention.