Ornithogalum cuspidatum mucilage as a new source of plant-based polysaccharide: Physicochemical and rheological characterization

Abstract

The aim of this research was to introduce and characterize a novel plant-based polysaccharide. Ornithogalum cuspidatum (OC) was used for mucilage extraction and chemical, physical, thermal and rheological properties of raw extracted mucilage (OMA), purified (OMB) and acid hydrolyzed mucilage (OMC) were compared. The purified mucilage (OMB) had the highest molecular weight (1.7 × 106 kDa). Nuclear magnetic resonance spectroscopy showed that the extracted mucilage is a member of arabinogalactan family. high performance liquid chromatography analysis showed that the mucilage is a hetropolysaccharide composed of galactose, glucose, arabinose and galacturonic acid, that galactose was the main monosaccharide in all samples. The functional groups and morphology of samples were characterized by Fourier transform infrared and Field emission scanning electron microscope analyses, respectively. Zeta potential was negative for three samples indicating the anionic nature of mucilage. The thermal analysis showed that the highest thermal stability was related to sample OMC. Water holding capacity of sample OMB was significantly higher than other two samples (p < 0.05). According to rheological studies, pseudoplastic behavior of three samples was confirmed. Sample OMB had the highest viscosity, and three samples followed the Herschel Balkley model. In the frequency sweep test, the loss modulus of all samples was greater than the storage modulus that indicates a weak gel structure of mucilage. In general, this research revealed that the OC mucilage as a liquid viscoelastic material can be introduced as a new thickener or stabilizer in food industry and purification and partial hydrolysis can affect its physicochemical and functional properties.