Extraction of basil seed gum: Optimization and functional properties

Abstract

Basil seed gum (BSG), a natural vegetable gum, was extracted by ethanol precipitation method using basil seeds as raw material. Based on the single factor experiments, Box-Behnken response surface test was performed to optimize the extraction conditions, and the physicochemical and functional properties of the extracted basil seed gum, as well as its microstructure, were analyzed in detail. The results showed that the optimal extraction conditions of basil seed gum were as follows: liquid-to-feed ratio of 62:1, temperature of 50 °C, extraction time of 29.50 min, and pH = 8.1, with yield of 11.28 %. BSG was mainly composed of total sugars (93.09 %), uronic acid (18.83 %), proteins (2.77 %), and ash (4.35 %), and its monosaccharides included D-(+)-anhydrous glucose (58.26 %), D-galactose (21.40 %), D-mannose (11.96 %), D-(+)-galacturonic acid (7.82 %), D-arabinose (0.28 %), D-(+)-xylose (0.28 %), and L-rhamnose (0.002 %). Comparative analysis of the functional properties of basil seed gum and three commercial vegetable gums (linseed gum, caraway seed gum, guar gum) showed that basil seed gum had excellent water retention properties, and its water absorption and water holding properties were much better than those of three commercial gums. Rheological characterization showed that BSG was a pseudoplastic fluid with high zero-shear viscosity. In addition, the basil seed gum powder showed an irregular flaky fibrous structure under microscope and was a semi-crystalline polymer. In view of the high aqueous absorption and retention properties of basil seed gum, it has promising applications in food, cosmetic and medical devices.