Relationship of thermal properties and ergosterol content of barley grains

Ergosterol is a sterol produced by fungi, and it is not found in healthy barley grains. The presence of ergosterol could be indicative of a fungal infection in grain. This study aimed to determine the correlations between the thermal properties and the ergosterol content of barley grain. Measurements were performed in transmittance mode in a wavelength range of 570-1100 nm to determine the ergosterol content of barley grain. Thermal parameters, including thermal conductivity, thermal resistivity, volumetric heat capacity and thermal diffusivity, were investigated using the KD2 Pro Thermal Properties Analyser with a dual-needle SH-1 sensor. Two thermal analysis methods, differential scanning calorimetry and thermogravimetric analysis, were additionally deployed to determine the thermal properties of grain. A significant positive linear correlation was noted between ergosterol content vs. thermal conductivity, volumetric heat capacity and the area under the DSC curve, and a negative correlation was noted between ergosterol content vs. thermal resistivity and the second and third endothermic peaks of phase transition in grain. The highest value of the correlation coefficient (0.96) was determined between the ergosterol content ratio and thermal conductivity. Regression equations were developed based on thermal properties to estimate the ergosterol content of grain.