Structural changes of proteins in fresh noodles during their processing

Figures & data

Figure 1. Method of sampling and sample analysis in fresh noodle processing.

Figure 2. Changes in the total protein content in the fresh noodle processing. Sampling point 1 means wheat flour; sampling point 2 means mixed dough; sampling point 3 means rested dough; sampling point 4 means sheeted noodles; sampling point 5 means cooked noodles. Superscripts denote significant difference (p < 0.05).

Figure 3. SDS-PAGE profiles of the total protein in the fresh noodle processing.

Table 1. The contents of accessible thiol (SH_free), total thiol equivalent (SH_eq), and disulfide groups (SS) in the fresh noodle processing.

	Accessible thiol [SHfree](μmol/g)	Total thiol equivalent [SHeq] (μmol/g)	Disulfide groups [SS] (μmol/g)
Wheat flour	50.96 ± 2.60^a	122.98 ± 0.16^b	36.01 ± 1.22^d
Mixed dough	44.34 ± 1.56^b	126.54 ± 2.39^a	41.10 ± 0.42^c
Rested dough	45.66 ± 0.10^b	125.77 ± 0.36^ab	40.06 ± 0.23^c
Sheeted noodles	37.94 ± 0.83^c	126.51 ± 0.68^a	44.28 ± 0.75^b
Cooked noodles	13.20 ± 0.26^d	128.09 ± 0.52^a	57.44 ± 0.13^a

Values in the same column followed by the same letter are not significantly different (p < 0.05).

Figure 4. The change in the wheat proteins secondary structures in the fresh noodle processing. (I) FT-IR spectrum of wheat proteins in different fresh noodles processing shown in the range 400–1800 cm^–1 after baseline correction. (II) Proportions of the secondary structures of wheat proteins in the fresh noodles processing. Values on the pie chart means the percentage of each secondary structure.

Table 2. Thermal characteristic parameters of gluten proteins in the fresh noodle processing.

Gluten samples	Denaturation temperature Tp(°C)	Enthalpy values ΔH(J/g)
Wheat flour	86.08	159.40
Mixed dough	78.86	128.94
Rested dough	83.25	131.72
Sheeted noodles	90.14	143.45
Cooked noodles	86.12	182.50

Figure 5. DSC curves of gluten proteins in the fresh noodle processing.

Figure 6. SEM photos of gluten proteins in the fresh noodle processing. (A) Wheat flour gluten, (B) mixed dough gluten, (C) rested dough gluten, (D) sheeted noodle gluten, (E) cooked noodle gluten.

Figure 7. The change in the mean particle size of gluten proteins in the fresh noodles processing. Sampling point 1 means wheat flour gluten; sampling point 2 means mixed dough gluten; sampling point 3 means rested dough gluten; sampling point 4 means sheeted noodles gluten; sampling point 5 means cooked noodles gluten. Superscripts denote significant difference (p < 0.05).