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This study investigated a new gum sourced from Acacia cambagei, Gidyea gum, by comparative characterisation with gum Arabic. The polysaccharide compositional analysis of Gidyea gum via Fourier transfer infrared and nuclear magnetic resonance spectroscopies was conducted, showing common structural features to gum Arabic, with minor differences in polymer branching. Microstructural imaging using transmission electron microscopy revealed the typical globular arabinogalactan glycoprotein structures of ∼10 nm diameter for both samples. Size exclusion chromatography also confirmed a similar molecular weight with 28 × 103 g mol−1 and 25 × 103 g mol−1 for Gidyea gum and gum Arabic, respectively. Gum rheological analysis determined a significantly lower apparent viscosity in the Gidyea gum. Modelling of the temporal evolution of dynamic surface and interfacial tensions revealed that Gidyea gum had a significantly lower rate of diffusion to the interfaces but similar adsorption and rearrangement rates. The dilatational viscoelastic response of Gidyea gum at the oil-water interface was consistent with gum Arabic, indicating similarities in functional performance. Indeed, Gidyea gum could stabilise orange oil-water emulsions for 15 days, exhibiting a comparable performance to those stabilised with gum Arabic. This study revealed that Gidyea gum is a functional emulsifier with the potential to be a gum Arabic alternative within the food and pharmaceutical industries.
Hay et al. (Wed,) studied this question.