Stock gum solution: Solutions of 6% gum with 0.12% preservative (sodium benzoate) and 0.36% citric acid were prepared by slowly adding the gum sample with vigorous stirring to a solution of sodium benzoate and citric acid in water at ambient temperature and then gently stirring overnight to produce a homogeneously hydrated solution (Yadav & Nothnagel, 2006).