Extraction, Purification, And Physicochemical Characterization of Seed Galactomannans

The galactomannans as endosperm mucilage were extracted from seeds of Caesalpinia pulcherrima and Delonix regia. Crude galactomannans were then purified by using isopropanol precipitation, the purified galactomannan yields of 75 and 82% of crude mass were obtained for Caesalpinia pulcherrima, Cassia fistula, and Delonix regia, respectively. The physicochemical properties of both crude and purified galactomannans were analyzed. The results showed that the crude galactomannans revealed high protein content which eliminated after purification. Crude galactomannans obtained 3.46 and 6.12 of mannose to galactose (M/G) ratio for Caesalpinia pulcherrima and Delonix regia, respectively. After purification the M/G ratio exhibited lower: 2.92 for Caesalpinia pulcherrima and 4.72 for Delonix regia. The intrinsic viscosity and viscosity average molecular mass of galactomannan samples were estimated by using Huggins’ and Kraemer equations and the Mark-Houwink relationship, respectively. The obtained results showed that the intrinsic viscosity of purified galactomannans increased when compared with crude galactomannans. It indicated that the purification process used alter the chemical structure. Since the intrinsic viscosity directly resulted in chemical structure as M/G ratio.

Keywords: Galactomannan, Extraction, Purification, Intrinsic viscosity, Caesalpinia pulcherrima, Delonix regia

E-mail: wancheng@buu.ac.th