Modification of Gelatine with Galla chinensis Extract, a Natural Crosslinker

Figures & data

FIGURE 1 (a) Gel strength of hydrogels with and without GCE at 4ºC; (b) Elastic modulus (G′), viscous modulus (G″), and phase angle of hydrogels with and without GCE.

FIGURE 2 (a) DSC thermographs of gelatin with and without GCE; (b) Thermogravimetry (TG) and derivative thermogravimetry (DTG) of gelatin with and without GCE.

TABLE 1 The temperatures of 50% mass (T₅₀), the residue at 500°C, the temperature corresponding to the maximum rate of mass loss (T_m), the maximum rate of mass loss of the control and different gelatin-GCE

Samples	T50 (°C)	Residue at 500°C (%)	Tm (°C)	Maximum rate of mass loss (%/min)
Control	345.5	30.1	315.0	–5.6
G-GCE3	362.7	35.7	313.0	–5.0
G-GCE4	357.2	32.2	328.3	–5.3

FIGURE 3 Swelling kinetics of xerogels with and without GCE.

TABLE 2 Degree of crosslinking, expressed as the percent of free ε-amino groups lost after crosslinking

Samples	Degree of crosslinking (%)^a
G-GCE1	56.8 ± 1.5
G-GCE2	76.4 ± 1.2
G-GCE3	78.3 ± 0.8
G-GCE4	68.9 ± 1.9

^aEach value is the mean of three determinations and is reported with its standard deviation.

TABLE 3 Crystallinity (X_c) of the samples with different GCE contents

Samples	Control	G-GCE1	G-GCE2	G-GCE3	G-GCE4
Crystallinity	14.69	14.25	14.06	13.73	13.97

FIGURE 4 (a) X-ray diffraction diagrams of gelatin with and without GCE; (b) FT-IR spectra of gelatin with and without GCE (control and G-GCE3).

FIGURE 5 SEM micrographs of films surface: (A1) control; (B1) G-GCE3 and SEM micrographs of films cross-sections; (A2) control; (B2) G-GCE3.