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Research Article

Exopolysaccharide from marine microalgae belonging to the Glossomastix genus: fragile gel behavior and suspension stability

, , , , , , , , , , , & ORCID Icon show all
Article: 2296257 | Received 16 Oct 2023, Accepted 13 Dec 2023, Published online: 28 Dec 2023

Figures & data

Table 1. Biochemical composition of EPS from Glossomastix sp. RCC3707 and RCC3688.

Table 2. Oligosaccharide sequences identified by ultra-high-pressure liquid chromatography-mass spectrometry untargeted in-source fragmentation (UHPLC-MS2) from EPS-3707.

Figure 1. Elution profiles of EPSs (LiNO3 at 0.1 mol L−1): Light Scattering signal (LS), dash line curves; Differential Refractive Index (DRI), full line curves; and molar mass distributions.

Figure 1. Elution profiles of EPSs (LiNO3 at 0.1 mol L−1): Light Scattering signal (LS), dash line curves; Differential Refractive Index (DRI), full line curves; and molar mass distributions.

Figure 2. a) Viscosity of EPS-3707 (upward: fill circles; downward: blank circles) b) elastic and viscous moduli of EPS-3707 (G’ fill and G’’ blank circles) c) viscosity of EPS-3688 (upward: fill circles; downward: blank circles) d) elastic and viscous moduli of EPS-3688 (G’ fill and G’’ blank circles) colour for the symbols : 20 g L−1 (red), 10 g L−1 (blue), 5 g L−1 (green), 1 g L−1 (black) and 0.5 g L−1 (pink) in water at 25°C.

Figure 2. a) Viscosity of EPS-3707 (upward: fill circles; downward: blank circles) b) elastic and viscous moduli of EPS-3707 (G’ fill and G’’ blank circles) c) viscosity of EPS-3688 (upward: fill circles; downward: blank circles) d) elastic and viscous moduli of EPS-3688 (G’ fill and G’’ blank circles) colour for the symbols : 20 g L−1 (red), 10 g L−1 (blue), 5 g L−1 (green), 1 g L−1 (black) and 0.5 g L−1 (pink) in water at 25°C.

Table 3. Comparison between the yield stress (σ0) and the limit stress (σlim) and characteristics at the cross point for the two EPSs at different concentrations in water at 25°C.

Figure 3. Flow curves : effect of salinity on viscosity of a) EPS-3707 and b) EPS-3688 solutions for various concentrations in water and NaCl 0.15M; c) effect of NaCl concentration on viscosity of EPS-3707 at 1 g L−1; d) effect of salt nature on viscosity of EPS-3707 solutions at 1 g L−1; e) effect of salt nature on viscosity of EPS-3688 solutions at 5 g L−1 in water, KSCN 0.2 mol L−1 and NaCl 0.2 mol L−1.

Figure 3. Flow curves : effect of salinity on viscosity of a) EPS-3707 and b) EPS-3688 solutions for various concentrations in water and NaCl 0.15M; c) effect of NaCl concentration on viscosity of EPS-3707 at 1 g L−1; d) effect of salt nature on viscosity of EPS-3707 solutions at 1 g L−1; e) effect of salt nature on viscosity of EPS-3688 solutions at 5 g L−1 in water, KSCN 0.2 mol L−1 and NaCl 0.2 mol L−1.

Figure 4. Effect of salinity on oscillation measurements. Left axis: elastic and viscous moduli, right axis: complex viscosity versus frequency of a) EPS-3707 1 g L−1 in water and NaCl 0.15 mol L−1; b) EPS-3707 5 g L−1 in water and NaCl 0.15 mol L−1; c) of EPS-3688 1 g L−1 in water and NaCl 0.15 mol L−1; d) of EPS-3688 5 g L−1 in water and NaCl 0.2 mol L−1; G’ (fill circle); G’’ (blank circle); complex viscosity (fill triangle).

Figure 4. Effect of salinity on oscillation measurements. Left axis: elastic and viscous moduli, right axis: complex viscosity versus frequency of a) EPS-3707 1 g L−1 in water and NaCl 0.15 mol L−1; b) EPS-3707 5 g L−1 in water and NaCl 0.15 mol L−1; c) of EPS-3688 1 g L−1 in water and NaCl 0.15 mol L−1; d) of EPS-3688 5 g L−1 in water and NaCl 0.2 mol L−1; G’ (fill circle); G’’ (blank circle); complex viscosity (fill triangle).

Figure 5. Restructuration of weak gel from EPS-3707 after high shear rate treatment at 25°C. Measurement at 0.1 Hz in the linearity domain a) 20 g L−1 in water b) 20 g L−1 in NaCl 0.15 mol L−1 c) 1 g L−1 in NaCl 1 mol L−1.

Figure 5. Restructuration of weak gel from EPS-3707 after high shear rate treatment at 25°C. Measurement at 0.1 Hz in the linearity domain a) 20 g L−1 in water b) 20 g L−1 in NaCl 0.15 mol L−1 c) 1 g L−1 in NaCl 1 mol L−1.

Table 4. The EI and SLB values of EPSs and alginate solutions in water at 1 g/L in function of temperature.

Table 5. The EI values (x 104 (nm−2)) of EPS-3688 solutions in water in function of concentration and temperature.

Figure 6. Elastic (G’) and viscous (G’’) moduli versus time at 25°C (blue), 37°C (red) and 60°C (green), of water solution EPS-3688 at 1 g L−1, at 1Hz and oscillation stress 0.01Pa.

Figure 6. Elastic (G’) and viscous (G’’) moduli versus time at 25°C (blue), 37°C (red) and 60°C (green), of water solution EPS-3688 at 1 g L−1, at 1Hz and oscillation stress 0.01Pa.

Figure 7. Percentage of transmission (y-axis) as a function of the height of the tube (x-axis) and time (curves from purple at t=0 to green and red at tmax) for a) suspensions of microcrystalline cellulose in pure water; b) suspensions of microcrystalline cellulose in EPS-3688 1 g L−1; c) suspensions of microcrystalline cellulose in alginate 10 g L−1; d) suspensions of microcrystalline cellulose in EPS-3707 1 g L−1.

Figure 7. Percentage of transmission (y-axis) as a function of the height of the tube (x-axis) and time (curves from purple at t=0 to green and red at tmax) for a) suspensions of microcrystalline cellulose in pure water; b) suspensions of microcrystalline cellulose in EPS-3688 1 g L−1; c) suspensions of microcrystalline cellulose in alginate 10 g L−1; d) suspensions of microcrystalline cellulose in EPS-3707 1 g L−1.

Figure 8. Percentage of transmission with ageing time of suspensions of microcrystalline cellulose.

Figure 8. Percentage of transmission with ageing time of suspensions of microcrystalline cellulose.
Supplemental material

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Data availability statement

The authors confirm that the data supporting the findings of this study are available within the article and its supplementary materials, and may be shared upon request.