Protein structure and sulfhydryl group changes affected by protein gel properties: process of thermal-induced gel formation of myofibrillar protein

Figures & data

Figure 1. Hardness of myofibrillar protein gel heated at different temperatures

^*a-gDifferent letters indicate significant differences between means (P < 0.05)

Figure 2. Water-holding capacity of myofibrillar protein gel heated at different temperatures

^*a-eDifferent letters indicate significant differences between means (P < 0.05)

Figure 3. Reactive and total sulfhydryl (SH) groups of myofibrillar protein gel heated at different temperatures

Figure 4. SDS-PAGE of supernatants protein in myofibrillar protein gel heated at different temperatures

Notes: STD: standards; A: CK; B: 30°C; C: 35°C; D: 40°C; E: 45°C; F: 50°C; G: 55°C; H: 60°C; I: 65°C; J: 70°C; K: 75°C; L: 80°C. MHC: myosin heavy chain; MLC: myosin light chain.

Figure 5. Raman spectra in 400–2000 cm⁻¹ region of myofibrillar protein gels heated at different temperatures

Notes: (a) CK; (b) 30°C (c) 40°C; (d) 50°C; (e) 60°C; (f) 70°C; (g) 80°C.

Figure 6. Raman spectra in 400–2000 cm⁻¹ region of myofibrillar protein gels heated at different temperatures

Notes:

: α-helix;

: β-sheet;

: β-turn;

: random coil

Figure 7. S-S stretch in 450–600 cm⁻¹ region of myofibrillar protein gel heated at different temperatures

Notes: (a) CK; (b) 30°C; (c) 40°C; (d) 50°C; (e) 60°C; (f) 70°C; (g) 80°C.

Table 1. Normalized intensity of the 760 cm⁻¹ band, the 1450 cm⁻¹ band, and normalized ratio of I850/I830 doublet bands

Name	I-760	I-850/830	I-1450
CK	0.33 ± 0.01^a	0.95 ± 0.05^e	2.72 ± 0.07^a
30°C	0.32 ± 0.02^a	0.40 ± 0.02^f	2.66 ± 0.18^a
35°C	0.29 ± 0.02^ab	0.88 ± 0.04^e	2.53 ± 0.03^ab
40°C	0.27 ± 0.01^ab	0.93 ± 0.02^e	2.45 ± 0.06^ab
45°C	0.26 ± 0.01^ab	1.02 ± 0.05^e	2.27 ± 0.04^ab
50°C	0.24 ± 0.02^bc	1.38 ± 0.09^cd	2.12 ± 0.12^bc
55°C	0.23 ± 0.02^bc	1.50 ± 0.02^c	2.11 ± 0.03^bc
60°C	0.18 ± 0.01^cd	1.53 ± 0.02^c	2.09 ± 0.08^bc
65°C	0.17 ± 0.02^cd	1.83 ± 0.06^b	2.08 ± 0.08^bc
70°C	0.14 ± 0.01^d	3.18 ± 0.01^a	1.72 ± 0.13^c
75°C	0.13 ± 0.02^d	1.30 ± 0.02^d	1.67 ± 0.15^c
80°C	0.13 ± 0.01^d	0.35 ± 0.03^f	1.62 ± 0.05^c

*^a-f Different letters in the same column indicate significant differences between means (P< 0.05)

Table 2. Pearson correlation of gel properties and secondary structure of myofibrillar protein gels heated at different temperatures

	A	B	C	D	E	F	G
A	1	0.464*	0.350*	0.471*	0.193	−0.442*	0.212
B		1	0.952**	0.878**	0.785**	−0.982**	0.870**
C			1	0.780**	0.915**	−0.934**	0.864**
D				1	0.461**	−0.894**	−0.727**
E					1	−0.747**	0.756**
F						1	−0.875**
G							1

Notes: A: hardness; B: water holding capacity; C: total sulfhydryl group; D: reactive sulfhydryl group; E: disulfide bonds; F: β-sheet; G: I-760. * indicates significant differences between means (P< 0.05), ** indicates significant differences between means (P< 0.01).