Mechanical and structural properties of rabbit skin gelatin films

Figures & data

Table 1. Thickness and water vapour permeabilities of the rabbit skin gelatin films and porcine skin gelatin films.

	Thickness (μm)			WVP×10^−12 (g·cm/cm^2·s·Pa)
Film type	4 g + 22%	4 g + 30%	5 g + 30%	4 g + 22%	4 g + 30%	5 g + 30%
RG	65 ± 2^b	84 ± 2^a	93 ± 5^a	3.1 ± 0.1^b	3.9 ± 0.1^a	4.1 ± 0.1^a
PG	73 ± 2^c	92 ± 2^b	103 ± 2^a	3.1 ± 0.1^c	4.1 ± 0.1^b	4.5 ± 0.1^a

Statistical difference (p < 0.05) within all samples from each gelatin films is denoted respectively by letters

Table 2. Colour parameters of the rabbit skin gelatin films and porcine skin gelatin films.

Film type		L*	a*	b*
RG	4 g + 22%	96.47 ± 0.07^a	−0.30 ± 0.04^a	2.93 ± 0.01^b
	4 g + 30%	96.4 ± 0.1^a	−0.28 ± 0.04^a	2.79 ± 0.06^b
	5 g + 30%	96.13 ± 0.07^b	−0.27 ± 0.01^a	3.27 ± 0.03^a
PG	4 g + 22%	96.56 ± 0.08^b	−0.26 ± 0.02^a	2.9 ± 0.2^b
	4 g + 30%	96.72 ± 0.05^ab	−0.27 ± 0.04^a	2.53 ± 0.09^a
	5 g + 30%	96.77 ± 0.09^a	−0.34 ± 0.04^a	2.9 ± 0.2^b

Statistical difference (p < 0.05) within all samples from each gelatin films is denoted respectively by letters.

Figure 1. Visual appearance of the films. a) RG films; b) PG films.

Table 3. Light transmission (%) and transparency of the rabbit skin gelatin films and porcine skin gelatin films.

		Wavelength (nm)
Film type		200	280	350	400	500	600	800	Transparency
RG	4g + 22%	0.36 ± 0.01^a	19.4 ± 0.6^a	82.3 ± 0.2^b	86.3 ± 0.4^b	88.9 ± 0.5^b	89.8 ± 0.7^b	90.4 ± 0.8^b	0.73 ± 0.05^a
	4g + 30%	0.3 ± 0.0^a	17.1 ± 0.8^c	85 ± 2^a	88 ± 2^a	90 ± 2^c	90 ± 1^a	91 ± 2^a	0.50 ± 0.09^c
	5g + 30%	0.25 ± 0.01^a	17.9 ± 0.7^b	81 ± 1^c	86 ± 1^c	87 ± 1^a	88 ± 1^c	89 ± 1^c	0.60 ± 0.07^b
PG	4 g+ 22%	0.31 ± 0.01^a	18.9 ± 0.4^a	83.2 ± 0.5^c	87.2 ± 0.5^b	89.5 ± 0.5^c	90.0 ± 0.5^c	90.6 ± 0.3^c	0.63 ± 0.03^a
	4g + 30%	0.27 ± 0.01^b	17.9 ± 0.4^b	86.3 ± 0.4^a	89.3 ± 0.4^a	91.3 ± 0.4^a	91.9 ± 0.3^b	92.3 ± 0.5^b	0.40 ± 0.01^b
	5g + 30%	0.23 ± 0.01^c	12.0 ± 0.9^c	85.8 ± 0.8^b	90.5 ± 0.6^c	91.1 ± 0.7^b	92.0 ± 0.7^a	92.5 ± 0.8^a	0.35 ± 0.03^c

Statistical difference (p < 0.05) within all samples from each gelatin films is denoted respectively by letters.

Figure 2. Protein patterns of the RG films and PG films. RG1, RG2, RG3: RG films 4 g + 22%, 4 g + 30%, 5 g + 30%. PG1, PG2, PG3: PG films 4 g + 22%, 4 g + 30%, 5 g + 30%.

Table 4. Water solubility of the RG and PG films.

Gelatin type	4 g + 22%	4 g + 30%	5 g + 30%
RG	39 ± 1^a	43 ± 2^a	32 ± 1^b
PG	42 ± 2^ab	43 ± 1^a	38 ± 1^b

Statistical difference (p < 0.05) within all samples from each gelatin films is denoted respectively by letters.

Table 5. TS, EAB and YM of the RG films and PG films.

	RG			PG
Film type	TS (MPa)	EAB (%)	YM (MPa)	TS (MPa)	EAB (%)	YM (MPa)
4g + 22%	35 ± 1^a	7.2 ± 0.6^b	6958 ± 120^a	32.8 ± 0.9^b	6.9 ± 0.9^b	6047 ± 123^b
4g + 30%	6.6 ± 0.4^b	188 ± 8^a	288 ± 54^b	9.2 ± 0.4^c	156 ± 5^a	930 ± 76^c
5g + 30%	35 ± 2^a	10 ± 1^b	7374 ± 219^a	54 ± 2^a	9 ± 1^b	8435 ± 335^a

Statistical difference (p < 0.05) within all samples from each gelatin films is denoted respectively by letters.

Table 6. Amide band position of the RG films and PG films.

Film type		Amide A wavenumber(cm^−1)	Amide B wavenumber(cm^−1)	Amide I wavenumber(cm^−1)
RG	4 g + 22%	3421.3	2930.2	1636.2
	4 g + 30%	3433.6	2928.3	1636.0
	5 g + 30%	3398.9	2928.4	1649.8
PG	4 g + 22%	3411.6	2927.4	1657.3
	4 g + 30%	3418.2	2928.3	1650.5
	5 g + 30%	3412.7	2928.8	1651.8

Table 7. Secondary structure contents of the rabbit skin gelatin films and porcine skin gelatin films.

	RG			PG
Film type	4 g + 22%	4 g + 30%	5 g + 30%	4 g + 22%	4 g + 30%	5 g + 30%
β-sheet	28.7 ± 0.4^b	30.1 ± 0.9^ab	30.6 ± 0.5^a	25.9 ± 0.7^b	26 ± 1^b	31.7 ± 0.6^a
Random coil	19 ± 1^b	21 ± 2^a	18.4 ± 0.7^b	21 ± 1^b	27 ± 2^a	15.7 ± 0.8^c
α-helix	38.6 ± 0.4^a	35.8 ± 0.4^b	35.3 ± 0.5^b	23.0 ± 0.8^b	12.7 ± 0.4^c	26 ± 2^a
β-turns	14 ± 2^ab	14 ± 1^b	15.8 ± 0.5^a	30.5 ± 0.9^b	34 ± 1^a	26 ± 1^c

Statistical difference (p < 0.05) within all samples from each gelatin films is denoted respectively by letters.

Figure 3. FT-IR spectra of the RG films.

Figure 4. FT-IR spectra of the PG films.

Figure 5. Fourier second-derivative and curve-fitting of the amide-I region (1700–1600 cm⁻¹) for the RG (Lower case letters) and PG (Uppercase letter) gelatin films.

Figure 6. Scanning electron microscopy of the surfaces of the films.a)RG:4 g + 22%; b) RG:4 g + 30%; c) RG:5 g + 30%; d) PG:4 g + 22%; e) PG:4 g + 30%; f) PG:5 g + 30%.

Figure 7. Scanning electron microscopy of the cross-sections of the films. a) RG:4 g + 22%; b) RG:4 g + 30%; c) RG:5 g + 30%; d) PG:4 g + 22%; e) PG:4 g + 30%; f) PG:5 g + 30%.