Effect of heating temperature on citric acid-locust bean gum synthesis

Background: Citric acid-locust bean gum (CA-LBG) is a derivative of locust bean gum. Its synthesis has been carried out previously using UV light as an energy source. Heat is an alternative energy source that is simple and affordable. Objective: To determine the effect of temperature on the synthesis of CA-LBG. Method: The synthesis of CA-LBG was achieved through the esterification process of citric acid (CA), locust bean gum (LBG), hydrochloric acid (HCl), and water bath. The temperatures used were 20oC, 40oC, 60oC, and 80oC for 30 minutes. CA-LBG was synthesised chemically and physically. Result: At 20oC, the viscosity of the mucilago was high, so mucilago was difficult to precipitate. At 80, the viscosity of the mucilago was very low, which affected the precipitation and denaturation process. The temperatures reported for further synthesis were 40°C and 60°C. FTIR spectra showed carbonyl ester as a specific group at 40°C (1738.6 cm-1) and 60°C (1735.1 cm-1). Evaluation of the effect of 40°C and 60°C heating on the swelling index was 3.09% and 3.15%; pH was 4.82 and 4.88; and yield was 39.76% and 37.18%, respectively. Conclusion: The higher temperature increased the UV wavelength, Mp, pH, and swelling index and decreased the yield.