The dehydration of paprika with ambient and heated air and the kinetics of colour degradation during storage

Abstract

The hygroscopic behaviour of dried red pepper is characterized by means of water vapour adsorption isotherms at 5, 20 and 35°C; from the GAB equation, a monolayer water content of 0·0816 kg H 2O per kg dry matter has been deduced. The effect of temperature on the drying rate of pepper is considered and yields are compared when the drying is carried out with ambient air and with different loading densities (10–40 kg m −2). The kinetics of paprika colour degradation during storage at different temperatures and with a moisture content corresponding to the monolayer have been studied. A sharp change in the rate of colour loss is observed at 15°C: the value Q 10 (°C) changes from 1·62 to 2·82 when the temperature rises above 15°C.