Physicochemical, rheological and functional properties of a novel gum from Eremurus luteus root

• Published in: Bioactive carbohydrates and dietary fibre 2022-05, Vol.27, p.100296, Article 100296
• Main Authors: Salahi, Mahdi, Razavi, Seyed Mohammad Ali, Hasanvand, Elham
• Format: Article
• Language: English
• Subjects: Eremurus luteus; Functional properties; Glucomannan; Rheology
• ISSN: 2212-6198; 2212-6198
• DOI: 10.1016/j.bcdf.2021.100296

The chemical compositions (moisture, total protein, total ash, total carbohydrate, total uronic acids), monosaccharides, and FTIR spectrum of Eremurus luteus root gum (ELRG), as a new source of hydrocolloid, were characterized and its functional properties were evaluated as a function of concentration (0.5–1.5, w/w%) and temperature (5–65 °C). The ELRG powder had, on average, 6.27% (w.b.) moisture, 4.17% (d.b.) ash, 6.22% (d.b.) protein, 86.45% (d.b.) carbohydrate and 8.6% (d.b.) uronic acids. The HPLC and FTIR analyses revealed that the polysaccharide of ELRG is a glucomannan with a 1.1:1 glucose/mannose ratio. The intrinsic viscosity values of ELRG, calculated by Huggins and Kraemer equations, were 6.32 and 6.35 dl g−1, respectively. ELRG dispersions exhibited a shear thinning behavior at all concentrations and temperatures. The flow behavior of ELRG dispersions was characterized by the power-law model in the shear rate range of 14–600 s−1 with high R2 and low RMSE values. The activation energy of ELRG, quantified using an Arrhenius-type equation, decreased from 22.49 to 16.82 (kJ/mol) as the concentration changed from 0.5% to 1.5% (w/w). The results showed that by increasing the ELRG concentration from 0.25% to 2% (w/w), the foaming capacity and foaming stability were decreased from 84% to 80% and from 72% to 56%, respectively. The rheological characteristics indicated potential applications of the ELRG as a novel thickener, stabilizer, and foaming agent.