Chemical composition and thermal properties of Pistacia atlantica subsp. Kurdica gum

Pistacia atlantica subsp. Kurdica (PAK) is distributed throughout the Zagros Mountains and is indigenous to Kurdistan province in western Iran. This study focused on the composition and thermal properties of gum extracted from female and male trees from six regions of Kurdistan province. Significant differences were detected in the total protein, total ash, total carbohydrate and monosaccharaide contents according to gender and geographic region, but no significant difference was found for moisture content. Analysis of the monosaccharide composition using HPLC showed the presence of arabinose, galactose, glucose, rhamnose and xylose. Significant differences were observed for the amino acid contents of the various PAK gum samples. The most abundant amino acids were glutamic acid, aspartic acid, serine, proline and histidine; however, the relative proportions of amino acids varied considerably between samples. The results indicate that the volatile components (VoC) were significantly different between samples according to gender and region, with the predominant VoC being α-Pinene. The results of thermogravimetric analysis showed that the onset of the initial and main decomposition of the samples was at 80 °C and above 240 °C, respectively. The differential scanning calorimetry results showed that nearly all gum samples included two glass transition temperatures and heat capacity values and that nearly all of the values for the female gum samples were lower than for the male samples.