Fractionation and some physicochemical properties of almond gum (Amygdalus communis L.) exudates

• Almond gum exudates were fractionated in two parts: water soluble and water insoluble.
• Whole gum and its fractions were characterized and compared.
• Almond gum and its fractions indicated high thermal stability.
• Molecular weight of the insoluble fraction was higher than those of the other two.

Compositions of both soluble and insoluble fractions of gum exudates from the trunk and branches of sweet almond tree (Amygdalus communis L.) were investigated. Monosaccharide analysis by HPLC indicated the presence of galactose and arabinose as the main sugars. FTIR spectra showed no significant differences between the functional groups of the whole gum and those of its fractions. Furthermore, only the intensity of OH and amide bond in the insoluble fraction was found to be higher than those of the soluble fraction and whole gum. XRD analysis revealed the amorphous structures of the whole gum and its fractions. Higher crystallinity index and crystalline size were observed in the insoluble fraction than in either the whole gum or the soluble fraction. TGA analysis revealed that the thermal decomposition of almond gum and its fractions occurred at around 250–260 °C. Finally, GPC analysis showed that the insoluble fraction had a higher molecular weight than did the whole gum or its soluble fraction.

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