Chilli (Capsicum annuum L.) is presently roasted using conduction heating in electrically-heated mechanical roasters. In this study, the possibility of using Far-Infrared (FIR) radiation heating for roasting chilli was investigated. The moisture content, temperature and colour variation of chilli pods at 3240, 3920, 5260 and 7188 W/m2 FIR radiation intensities with different exposure times were measured. The colour of the factory roasted chilli pods prepared using a drum roaster at 120°C for 25 min were 30.73(L*), 9.33(a*) and 48.51(b*). These values were used as the standard and compared with the colour values of chilli roasted with FIR radiation. The factory-roasted colour of chilli pods was achieved in 60 s at the highest intensity of FIR radiation (7188 W/m2) used in the experiment. The chilli temperature rose above 100°C and the moisture content reached 9.02% (dry basis - db) at 60 s FIR exposure with 7188 W/m2. At the radiation intensities of 3240, 3920, 5260 W/m², the factory-roasted colour of chilli was achieved at 124, 117, 107 s and the corresponding interpolated moisture contents were 8.38, 6.70 and 6.59% db, respectively.
Tropical Agricultural Research Vol. 25 (2): 180 – 187 (2014)