PH—Postharvest Technology: Determination of Thermal Conductivity, Specific Heat and Thermal Diffusivity of Borage Seeds

Abstract

Thermal conductivity, specific heat capacity and thermal diffusivity of borage ( Borago officinalis) seeds were determined at temperatures ranging from 6 to 20°C and moisture contents from 1·2 to 30·3% w.b. The thermal conductivity was measured by the transient technique using a line heat source. The maximum slope method was used to analyse the line source heating data for thermal conductivity determination. The specific heat capacity was measured by different scanning calorimetry and ranged from 0·77 to 1·99 kJ kg −1K −1. The thermal conductivity of borage seeds ranged from 0·11 to 0·28 W m −1 K −1 and increased with moisture content in the range of 1·2–30·3% w.b. The thermal diffusivity ranged from 2·32×10 −7 to 3·18×10 −7 M 2 S −1. Bulk density of borage seeds followed a parabolic relationship with moisture content. Uncertainty analysis revealed that variation in the thermal conductivity contributed mostly to the accuracy of the thermal diffusivity.