Modifikasi Galaktomanan Biji Aren (Arenga Pinnata Merr.) Menjadi Galaktomanan Stearat Melalui Transesterifikasi Menggunakan Katalis NaHCO3 dengan Radiasi Mikrowave

Abstract

Galactomannan stearat was modified by transesterification of galactomannan from sugar palm (Arenga pinnata Merr.) seeds with methyl stearat using NaHCO3 catalyst under microwave irradiation at 50 P for 15 minutes. Galactomannan stearat obtained was analyzed by FT-IR, SEM, degree of substitution by titration method. Emulsion stability is determined by measuring the emulsion stability index (ISE). Methyl stearat was obtained by esterification of stearic acid with methanol using H2SO4(p) catalyst and heating using a microwave at a power of 50 P for 30 minutes. Based on the observation of the reaction using TLC, the reaction for the formation of methyl stearat lasted for 30 minutes. The methyl stearat obtained was analyzed by FT-IR spectrophotometer. Galactomannan is obtained through an extraction process from fro using water as a solvent, followed by the addition of ethanol and drying. Galactomannan obtained was analyzed by FT-IR spectrophotometer and SEM. Modification to galactomannan stearat was carried out at various mole ratios of galactomannan to methyl stearat at a ratio of 1:1 (ᵂ/ᵥ), 1:2 (ᵂ/ᵥ), 1:3 (ᵂ/ᵥ). The formation of galactomannan stearat is indicated by the presence of absorption bands at wave number 1743.65 cm-1 at mole variation 1:1 (ᵂ/ᵥ), 1741.72 cm-1 at mole variation 1:2 (ᵂ/ᵥ), and 1741, 72 cm-1 at mole variation 1:3 (ᵂ/ᵥ), which indicates the presence of the C=O ester carbonyl group. The formation of methyl stearat was indicated by the presence of an absorption band at wave number 1743 cm-1 indicating the presence of a C=O ester group. The highest DS value was obtained at the 1:2 (ᵂ/ᵥ) variation, namely 0.32. Emulsion stability on galactomannan and galactomannan stearat at a ratio of 1:1 (ᵂ/ᵥ), 1:2 (ᵂ/ᵥ), and 1:3 (ᵂ/ᵥ) obtained galactomannan stearat at a ratio of 1:3 (ᵂ/ᵥ) has the most stable ISE (ISE = 0.89) with a DS value of 0.043. The results of the SEM analysis showed that the galactomannan surface morphology changes were not smooth and uneven and had many pores, while galactomannan stearat had fewer pores.