Viscoelastic Characterization of Sage Seed Gum

Figures & data

Figure 1 Compliance versus time for the Burger's model in creep/recovery test.

Figure 3 (Continued).

Figure 2 Stress dependence (1 Hz, 20°C) of (a) loss modulus and (b) storage modulus for sage seed gum at different concentrations (◊, 0.5%; □, 0.75%; △, 1%; ×, 1.25%; *, 1.5%; ◯, 1.75%; +, 2%).

Table 1  Frequency dependency of elastic and viscous moduli of SSG at different concentrations and constant temperature of 20°C

	Elastic modulus (G′)			Viscous modulus (G”)
Concentration (%)	n′	K′ (Pa.s)	R ^2	n″	K″ (Pa.s)	R ^2
0.5	0.20 ± 0.01	7.26 ± 0.54	0.986	0.37 ± 0.01	3.42 ± 0.24	0.965
0.75	0.22 ± 0.02	12.58 ± 1.25	0.983	0.41 ± 0.01	6.37 ± 0.60	0.987
1.0	0.22 ± 0.01	22.17 ± 1.98	0.978	0.41 ± 0.01	10.53 ± 0.68	0.981
1.25	0.22 ± 0.01	43.22 ± 0.93	0.987	0.39 ± 0.01	20.28 ± 0.51	0.991
1.5	0.22 ± 0.00	62.50 ± 9.85	0.989	0.36 ± 0.01	27.13 ± 3.20	0.994
1.75	0.22 ± 0.01	89.96 ± 5.88	0.988	0.38 ± 0.01	41.42 ± 1.68	0.994
2.0	0.24 ± 0.00	107.14 ± 2.91	0.993	0.38 ± 0.01	51.64 ± 0.69	0.996

Figure 5 Compliance versus time in “creep and recovery test” for sage seed gum at different concentrations (applied shear stress: 1 Pa; temperature: 20°C). (Color figure available online.)

Table 2  Creep parameters of the Burger model, obtained from the fits by Eq. (1), for sage seed gum at different concentrations (20°C).^a

Concentration (%)	J 0C (Pa^−1)	J 1C (Pa^−1)	η0 (10^−3 Pa.s)	λ ret (s)	r
0.5	0.341	0.781	0.434	13.23	0.988
0.75	0.136	0.232	2.017	6.89	0.983
1.0	0.072	0.106	4.077	7.00	0.983
1.25	0.045	0.063	6.368	7.04	0.987
1.5	0.026	0.032	12.037	7.18	0.988
1.75	0.020	0.025	12.687	7.15	0.988
2.0	0.017	0.022	15.782	7.46	0.989
^a J 0C and J 1C are the elastic compliance of Maxwell and Kelvin-Viogt springs, η0 is the viscosity of Maxwell dashpot, λ ret is the retardation time, and r is the correlation coefficient.

Figure 6 An example of prediction of creep compliance of SSG (2%) by the Burger model.

Table 3  Recovery parameters, obtained from the fits by Eqs. (2) and (3), for sage seed gum at different concentrations (20°C).^a

Concentration (%)	J 0R (Pa^−1)	J 1R (Pa^−1)	J ∞ (Pa^−1)	B (s^−c)	C	r
0.5	0.203	0.371	1.113	0.296	0.407	0.999
0.75	0.114	0.192	0.181	0.333	0.403	0.999
1.0	0.062	0.107	0.069	0.358	0.378	0.999
1.25	0.042	0.064	0.041	0.292	0.407	0.999
1.5	0.024	0.035	0.019	0.264	0.413	0.999
1.75	0.020	0.031	0.015	0.262	0.396	0.999
2.0	0.017	0.026	0.012	0.214	0.448	0.999
^a J 0R and J 1R are the recovery compliance of Maxwell and Kelvin-Viogt springs, J ∞ is the recovery compliance of Maxwell dashpot, B and C are the recovery speed of the system, and r is the correlation coefficient.

Table 4  Maximum compliance and creep/recovery normalized parameters for sage seed gum at different concentrations (20°C).^a

	Creep phase				Recovery phase
Concentration (%)	J max(Pa^−1)	J 0C * (%)	J 1C * (%)	J 2C *(%)	J 0R * (%)	J 1R * (%)	J ∞*(%)	R (%)
0.5	1.687	20.21	46.29	33.50	12.02	22.01	65.96	34.03
0.75	0.487	27.92	47.64	24.44	23.38	39.45	37.16	62.84
1.0	0.237	30.77	45.30	23.93	25.99	44.98	29.02	70.98
1.25	0.147	30.61	42.86	26.53	28.81	43.46	27.72	72.27
1.5	0.078	33.33	41.02	25.65	30.67	44.60	24.72	75.28
1.75	0.065	30.30	37.88	31.82	29.93	47.78	22.29	77.71
2.0	0.055	30.91	40.00	29.09	30.28	47.32	22.39	77.61
^a J max is the creep compliance at t = 300, J 0C *, J 1C *, J 2C *, J 0R *, J 1R *, and J ∞* are the percentage deformation of J 0C , J 1C , η0, J 0R , J 1R , and J ∞, respectively. R is the system recovery.

Table 5  In-shear recovery properties of sage seed gum as a function of concentration at 20°C.^a,b,c

Concentration (%)	η a1 (Pa.s)	η a2 (Pa.s)	η a3 (Pa.s)	Recovery (%)
0.5	2.157 ± 0.177	0.047 ± 0.026	1.275 ± 0.126	59.821 ± 9.417
0.75	3.313 ± 0.277	0.090 ± 0.024	1.833 ± 0.134	57.457 ± 7.941
1.0	5.643 ± 0.537	0.122 ± 0.022	3.216 ± 0.205	57.648 ± 7.849
1.25	8.004 ± 0.715	0.173 ± 0.034	4.703 ± 0.304	59.410 ± 8.217
1.5	8.579 ± 0.835	0.174 ± 0.020	4.272 ± 0.210	50.292 ± 5.923
1.75	15.693 ± 1.149	0.317 ± 0.041	8.891 ± 0.893	57.192 ± 8.841
2.0	15.947 ± 1.650	0.356 ± 0.022	9.677 ± 0.795	61.616 ± 10.200
^aData were the mean of 10 replications.
^bThe program in this test was: step 1, shear rate 1 s^−1 for 120 s; step 2, shear rate at 300 s^−1 for 60 s; step 3, shear rate at 1 s^−1 for 180 s.
^cη a1, η a2, and η a3 are the apparent viscosities of steps 1, 2, and 3, respectively. The recovery (%) is defined as (η a3/η a1) × 100.

Figure 3 Mechanical spectra (1% strain, 20°C) showing the variation of (a) loss modulus, (b) storage modulus, (c) complex modulus, and (d) loss tangent with frequency for sage seed gum at different concentrations (◊, 0.5%; □, 0.75%; Δ, 1%; ×, 1.25%; *, 1.5%; ◯, 1.75%; +, 2%).

Figure 4 Storage modulus (G′), loss modulus (G″), and loss tangent (Tan δ) of sage seed gum as a function of concentration (f = 1 Hz, T = 20°C) (◊, 0.5%; □, 0.75%; Δ, 1%; ×, 1.25%; *, 1.5%; ◯, 1.75%; +, 2%).