New studies on basil (Ocimum bacilicum L.) seed gum: Part I - Fractionation, physicochemical and surface activity characterization

Basil seed gum (BSG) was fractionated by non-solvent fractionation method (ethanol precipitation). Two fractions were obtained and called PER-BSG and SUPER-BSG which had the highest and lowest molecular weight (MW), respectively. Another fraction was obtained by protease treatment which protein moieties of BSG removed without making different in molecular weight. The molecular weight, moisture, ash, protein content, intrinsic viscosity, total sugar, total uronic acid, monosaccharide units, functional groups (FTIR) and surface tension were investigated for total BSG and all fractions. BSG was composed of 92.44% (w/w) sugar and 6.51% (w/w) uronic acid; while PER-BSG and SUPER-BSG comprised of 83.02% and 88.39% (w/w) sugar, and 3.84% and 13.39% uronic acid, respectively. FTIR results confirmed the presence of uronic acid as it had absorptions at wavenumber 1400 and 1600 cm(-1). Significant difference was determined between monosaccharide compositions of fractions; especially in xylose content which substantial value existed for SUPER-BSG (10%). The BSG exhibited higher intrinsic viscosity (39.27 dl g(-1)) in comparison to its fractions. BSG and all fractions had the same molecular conformation which random coil conformation was recognized in dilute regimes and SUPER-BSG had the highest chain flexibility. The SUPER-BSG imparted the best surface activity as it had the highest protein content and lowest MW. Decreasing protein content by enzyme hydrolysis led to surface activity of BSG reduced considerably by changing its hydrophobic character. This attribute confirmed that protein and molecular weight plays an important role in surface activity of BSG. (C) 2015 Elsevier Ltd. All rights reserved.