Understanding the structure–emulsification relationship of gum ghatti – A review of recent advances

• Detailed molecular structural features of gum ghatti fractions.
• Protein and polysaccharide linkages of gum ghatti.
• Protein moiety structure and the hydrophobicity of gum ghatti.
• Random coil conformation of gum ghatti.
• Structure–function relationship of gum ghatti.

This paper is based on a series of physical and chemical investigations to understand the structure–function properties of gum ghatti. After elucidating the detailed molecular structure of two gum ghatti fractions, the structure of its component glycoprotein was investigated whereby, the protein sequence and hydrophobicity were identified, followed by the conformational analysis of the gum and its fractions. Many techniques were used for the elucidation of the fine structures, which included methylation analysis-GC-MS, Maldi-TOF MS and 2D NMR spectroscopy, homonuclear 1H/1H correlations spectroscopy (COSY, TOCSY), heteronuclear 13C/1H multiple-quantum coherence spectroscopy (HMQC) and heteronuclear multiple bond correlation (HMBC). Conformational properties were studied using a modeling system (Insight II) to relate the hydrophobicity of the protein moieties with the complex structures of the carbohydrates. These studies now provide an explanation for the excellent emulsification properties of gum ghatti in oil-in-water emulsions, which enable its application in the food, cosmetic and/or pharmaceutical industries.

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