Development of emulsifying property in Persian gum using octenyl succinic anhydride (OSA)

• Optimization of esterification conditions of Persian gum and its soluble fraction.
• Confirmation of structural changes by FTRI spectra.
• Evaluation of emulsification capacity and activity by microscopic images.
• Improvement of functional properties of Persian gum.

In the present study, the influence of octenyle succinic anhydride (OSA),gum concentration, pH, temperature and reaction time on esterification of Persian gum (PG), and its soluble (SFPG) and insoluble (IFPG) fractions, were investigated by response surface methodology (RSM) in order to optimize the reaction conditions based on the degree of substitution (DS). The individual effect of all independent variables as well as the interactive effects of temperature–OSA concentration, and OSA–PG concentrations on DS was significant. However, the latter interactive effect (OSA–SFPG) was not significant in case of SFPG. The IFPG did not have any esterification reaction with OSA. The highest DS for PG and SFPG were 0.0285 and 0.0303 at the optimal conditions, respectively. The FTIR spectrums also confirmed the carbonyl group attachment in OSA-PG and OSA-SFPG. The enhancement of emulsifying capability was also confirmed by ECI and EAI values, microscopic images as well as rheological measurements.