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

Octenyl succinic anhydride (OSA) is is one of the alkenyl succinic anhydrates, which its food applications is approved. As a result of its esterification reaction with hydrocolloids, hydrophobic sides confer to hydrophilic hydrocolloid molecules and consequently emulsifying properties can be improved. Therefore, in this research, the influence of various parameters (concentration of gum and OSA, temperature and reaction time) on esterification reaction of Persian gum (PG) (whole gum, soluble and insoluble fractions) in order to achieve the highest degree of substitution (DS), as well as functional properties were investigated. According to our results, the highest rate of DS was obtained in whole PG and its soluble fraction at 8.5 and 6.2 wt% (concentration of gum), 7.75 and 6.6% (concentration of OSA, wt%), 42 ºC (temperature), 85 and 120 min (reaction time), respectively. The FT-IR spectroscopy confirmed the formation of carbonyl groups in OSA treated gums. In addition, our findings on emulsifying properties demonstrated that modification of PG and its soluble fraction by using OSA improved their emulsifying properties. Based on our microstructural observations, the emulsions contained high number of small particles and longer physical stability. Furthermore, rheological investigations showed that flow behavior as well as apparent viscosities were reasonably different than untreated PG and its soluble fraction.