Determination of physical and thermophysical characteristics of red peppers (Capsicum annum) using unsteady-state method

This study aimed at determining the physical and thermophysical characteristics of red peppers. The results of this study are expected to be a useful reference for red pepper farmers or industries to improve the red pepper drying process. The density of red peppers was determined based on the mass and volume of a single pepper, partial pepper (pericarp and seed), paste and round pieces. The thermal diffusivity was measured using unsteady-state method with a simple device based on the process of heat conduction. Heat transfer measurements were performed on the exocarp, mesocarp, and seed, as well as on round pepper pieces and pepper paste. A finite difference equation using the Crank–Nicolson mathematical model was used to calculate the thermal diffusivity of each sample based on the observed data of each sample. The specific heat of red pepper was determined using the Siebel equation. The results indicate that the thermal diffusivities among the part and sample form of red pepper (Capsicum annum) do not differ statistically, but the thermal conductivity among the samples is different. The thermal conductivity of red pepper paste was the highest (0.156 W/m°C), while that of exocarp was the lowest (0.0431 W/m C).