Effect of heat treatment on foaming properties of ostrich (Struthio camelus) egg white proteins

Figures & data

Figure 1. Effect of heat treatment on exposed sulfhydryl content (µM/gr of protein) of OEWS at pH 7.5 (white bars) and pH 9 (grey bars). For each individual pH, means with the same letter are not significantly different at p = 0.05.

Figure 2. Effect of heat treatment on SDS-PAGE patterns of OEWS under non-reducing conditions (without 2-ME) at pH 9 (a) and pH 7.5 (b).

Figure 3. Effect of heat treatment on SDS-PAGE patterns of OEWS under reducing conditions (with 2-ME) at pH 9 (a) and pH 7.5 (b).

Figure 4. Effect of heat treatment on Native-PAGE patterns of OEWS at pH 9 (a) and pH 7.5 (b).

Figure 5. Effect of heat treatment on turbidity of OEWS at pH 7.5 (empty symbols) and pH 9 (full symbols). For each individual pH, means with the same letter are not significantly different at p = 0.05.

Table 1. Foaming properties (average ± standard deviation) of OEWS after heat treatment.

	pH 7.5			pH 9
Sample	FC (%)	FS (%)	FD (gr/ml)	FC (%)	FS (%)	FD (gr/ml)
OEW-22°C	748 ± 7 ^a	93. 7 ± 1.1^a	0.11 ± 0.01^c	690 ± 4^a	93. 7 ± 0.6^a	0.134^a,b
OEW-55°C	750 ± 3 ^a	94.6 ± 1.9^a	0.12 ± 0.01^c	685 ± 5^a	94.1 ± 1.7^a	0.135^a,b
OEW-60°C	310 ± 11 ^e	92 ± 1.7^a	0.21 ± 0.01^a	636 ± 4^b	92.4 ± 2.1^a	0.136^a,b
OEW-65°C	660 ± 10 ^b	92.6 ± 1.1^a	0.14 ±0.03^b,c	630 ± 8^b	92.8 ± 1.3^a	0.136^a,b
OEW-70°C	743 ± 6 ^a	92.4 ± 0.9^a	0.16±0.001^b	440 ± 15^c	92.5 ± 1.3^a	0.131^b
OEW-75°C	661 ± 10 ^b	92.7 ± 1.2^a	0.16 ± 0.01^b	640 ± 12^b	92.2 ± 2^a	0.141^a
OEW-80°C	606 ± 11 ^c	94.7 ± 0.4^a	0.18 ±0.03^a,b	663 ± 34^a,b	93.7 ± 1.2^a	0.138^a,b
OEW-85°C	511 ± 12 ^d	93.5 ± 1^a	0.18 ±0.02^a,b	665 ± 35^a,b	94 ± 1^a	0.141^a

^{a, b, c, d} Same superscript letters in the same column indicate no significant differences between means at p = 0.05.

FC: foaming capacity, FS: foam stability, FD: foam density.

Figure 6. Effect of heat treatment on foaming capacity of OEWS at pH 7.5 (empty symbols) and pH 9 (full symbols). For each individual pH, means with the same letter are not significantly different at p = 0.05.

Figure 7. Effect of heat treatment on foam density (♦) and foam stability (▲) of OEWS at pH 7.5 (empty symbols) and pH 9 (full symbols). For each individual pH, means with the same letter are not significantly different at p = 0.05.