Rheological properties of chia seed gum extracted by high-speed shearing and its comparison with commercial polysaccharides

Chia seed gum was extracted using high-speed shearing technology and further purified via ethanol precipitation. The composition, structural and rheological properties of crude chia seed gum (CCSG) and purified chia seed gum (PCSG) were evaluated and further compared with twelve commercial polysaccharides (agar, xanthan gum, κ-/ι-/λ-carrageenan, guar gum, carboxymethyl cellulose, locust bean gum, pectin, acacia gum, sodium alginate and konjac gum). The extraction yields of CCSG were significantly improved from 1.80% to 6.25% by high-speed shearing for 2.0 min. Compared to CCSG (36.63% and 3.985 × 105 g/mol), PCSG had a higher total neutral sugar content (51.85%), lower molecular weight (1.718 × 105 g/mol) and looser surface morphology. Furthermore, PCSG and CCSG had different monosaccharide composition. However, both CCSG and PCSG exhibited pseudoplastic fluid behavior, but PCSG had higher viscosity and modulus values than CCSG at the same concentrations. Compared to commercial polysaccharides, PCSG had rheological characteristics similar to those of xanthan gum, with high viscoelasticity and good stability against temperature change. The relaxation time T2 curves showed that CCSG and PCSG had better water-holding capacity than most commercial polysaccharides. This study provided theoretical guidance for the potential utilization of chia seed gum as a thickening and stabilizing agent in the food industry.