Gas stunning with CO2 affected meat color, lipid peroxidation, oxidative stress, and gene expression of mitogen-activated protein kinases, glutathione S-transferases, and Cu/Zn-superoxide dismutase in the skeletal muscles of broilers

Table 1 Effects of gas stunning methods on meat color in broilers

Color²	Storage time	Stunning methods¹			P-value
Color²	Storage time	Control	G40%	G79%
Breast meat
L*	d 1	53.0 ± 0.81 ^a	55.7 ± 0.79 ^b	56.0 ± 0.77 ^b	0.03
	d 9	52.7 ± 0.61 ^a	56.0 ± 1.38 ^b	58.2 ± 0.51 ^b	< 0.01
a*	d 1	7.03 ± 0.41 ^b	5.20 ± 0.72 ^ab	4.48 ± 0.91 ^a	0.06
b*	d 6	14.0 ± 0.46 ^b	12.5 ± 0.76^ab	11.6 ± 0.82 ^a	0.08
E*	d 1	44.8 ± 0.68 ^c	43.4 ± 1.05 ^ab	41.7 ± 0.58 ^a	0.05
	d 3	47.11 ± 0.41^b	44.8 ± 0.68 ^a	44.3 ± 0.48 ^a	< 0.01
	d 6	43.1 ± 1.05 ^b	40.9 ± 1.02 ^ab	39.0 ± 0.90 ^a	0.04
	d 9	44.6 ± 0.53 ^b	41.9 ± 1.00 ^b	40.7 ± 1.05 ^a	0.02
Thigh meat
a*	d 6	7.12 ± 0.58 ^b	7.79 ± 0.92 ^b	4.16 ± 0.20 ^a	< 0.01
b*	d 1	12.9 ± 0.63 ^a	15.8 ± 0.97 ^b	10.7 ± 0.55 ^a	< 0.01
	d 3	15.5 ± 0.38 ^b	11.5 ± 1.46 ^a	11.2 ± 0.89 ^a	0.01
	d 6	13.7 ± 1.78 ^b	6.00 ± 0.59 ^a	7.73 ± 0.77^a	< 0.01
	d 9	8.66 ± 2.20 ^a	15.2 ± 2.06 ^b	12.7 ± 1.21 ^ab	0.08
E*	d 6	45.0 ± 1.02 ^b	40.7 ± 1.19 ^a	40.1 ± 0.89 ^a	< 0.01

¹Control = without stunning; G40% = 40% CO₂ + 21% O₂ + 39%N₂; G79% = 79% CO₂ + 21% O₂
²L* = lightness; a* = redness; b* = yellowness; E* = total chromatic aberration. Color was measured for meat that was stored at 4 °C for 0, 1, 3, 6 and 9 d post-mortem. However, data with P > 0.1 were omitted in the table
^a–c Means with no common superscripts within a row differ significantly (P ≤ 0.05) or exhibit differences that approach significance (0.05 < P < 0.10); n = 6; values are expressed as the means ± S.E.M

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