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

Abstract

BackgroundMeat color and lipid peroxidation are important traits related to meat quality. CO2 concentration is a critical factor that can affect meat quality in the commercial use of gas stunning (GS). However, the effect and mechanism of CO2 stunning on meat color and lipid peroxidation during long-term storage remain poorly studied. We aimed to study the effects of GS methods, especially CO2 concentration, on meat color and meat lipid peroxidation in broilers during long-term storage at 4 °C and to explore the potential mechanism of meat color change via lipid peroxidation and the inner lipid peroxide scavenging system.MethodsEighteen broilers were sacrificed after exposure to one of the following gas mixtures for 90 s: 40% CO2 + 21% O2 + 39% N2 (G40%), 79% CO2 + 21% O2 (G79%), or no stunning (0% CO2, control). Meat color, serum variables, enzyme activities, and the gene expression of mitogen-activated protein kinase (MAPK), nuclear factor-erythroid 2-related factor 2 (Nrf2), glutathione S-transferase (GST) and superoxide dismutase (SOD) were determined.ResultsThe concentrations of serum triiodothyronine (T3, P = 0.03) and the ratio of serum free triiodothyronine/free thyroxine (FT3/FT4, P < 0.01) were decreased, whereas levels of serum cortisol (P < 0.01) were increased in the 40% CO2 group compared with the control group. Additionally, the thiobarbituric acid-reactive substances (TBARS) 3 d (P < 0.01) and TBARS 6 d (P = 0.01) in breast meat and the TBARS 3 d in thigh meat (P < 0.01) were increased in the 40% CO2 group compared with the control group. Serum T3 was negatively correlated with TBARS6 d both in the breast and thigh meat (r = − 0.63, P < 0.01 and r = − 0.47, P = 0.05 respectively). T3/T4 was negatively correlated with TBARS6 d in the breast meat and in the thigh meat (r = − 0.57, P = 0.01; and r = − 0.53, P = 0.03 respectively). Compared with the control group, Lightness (L*) 1 d (P = 0.03) and L*9 d (P < 0.01) were increased, whereas total chromatic aberration (E*) 1 d (P = 0.05) and E*3 d (P < 0.01) were decreased in the breast meat of both the G40% and G79% groups. The values of yellowness (b*) 3 d (P = 0.01), b*6 d (P < 0.01) and E*6 d (P < 0.01) in the thigh meat were lower in both the G40% and G79% groups than in the control group. In the breast muscle, the mRNA levels of c-Jun N-terminal kinase 2 (JNK2, P = 0.03), GSTT1 (P = 0.04), and SOD1 (P = 0.05) were decreased, and the mRNA levels of JNK1 (P = 0.07), Nrf2 (P = 0.09), and GSTA3 (P = 0.06) were slightly lower in both the G40% and G79% groups compared with the control group. However, among these genes, only the mRNA level of JNK1 was decreased in the G40% group compared with the control group and the G79% group (P = 0.03) in the thigh muscle.ConclusionsCompared with the control group, meat color quality in the breast meat was decreased, and the expression of genes in the MAPK/Nrf2/ARE (antioxidant responsive element) antioxidant pathway in breast muscle was partly suppressed by GS of both 40% and 79% CO2. However, oxidative stress an...

Evaluation of the Effects of Pre-Slaughter High-Frequency Electrical Stunning Current Intensities on Lipid Oxidative Stability and Antioxidant Capacity in the Liver of Yangzhou Goose (Anser cygnoides domesticus)

“…The MDA level in the groups of control, E90V, and E120V all decreased at d 4 as compared with d 0 (p < 0.05) in the present study (Table 2). This is consistent with the changes of MDA level in breast meat at d 1 and d 9 [10] and in thigh meat at d 6 as compared with d 0 [20] in electrically stunned broilers. The decrease of MDA concentration may be due to further metabolisms of MDA through enzymatic and chemical reactions, resulting in the products of thromboxane A 2, acetaldehyde, acetate, or Schiff-base adducts as time went on [21,22].…”

“…Different from geese, previous studies of our team demonstrated that the MDA level in breast meat of broilers was not affected by ES methods [10] or controlled atmosphere stunning (CAS) methods at day 0 (d 0) [20]. Whereas when the refrigeration time was prolonged, MDA levels at day 1 (d 1) and day 3 (d 3) were increased by low-current and high-frequency combination compared to high-current and low-frequency combination [10], or by CAS with 40% CO 2 compared to 79% CO 2 at d 3 [20]. These differences among studies may be due to different ES variables, body resistance (geese vs. broilers), and measured tissues (liver vs. muscle).…”

Evaluation of pre‐slaughter low‐current/high‐frequency electrical stunning on lipid oxidative stability, antioxidant enzyme activity and gene expression of mitogen‐activated protein kinase/nuclear factor erythroid 2‐related factor 2 (MAPK/Nrf2) signalling pathway in thigh muscle of broilers

“…MDA decreased to the minimum level from d 0 to d 6 and recovered to the level of d 0 again in d 9 in the raw thigh meat of both ES‐treated birds ( P < 0.01, Table ), indicating a similar lipid oxidative stability in thigh meat between treatment LHES and treatment HLES. This tendency was similar with the breast meat from the same broilers treated by the same stunning methods (Xu et al , ) or similar with thigh meat from broilers stunned by controlled atmosphere stunning (Xu et al , ). Differently, Alvarado et al () reported an increase of MDA level from d 1 to d 4 (cooked breast meat) in broilers that were treated with different stunning methods.…”

“…This was similar to the breast muscle, as pre‐slaughter LHES also stimulated oxidative stress and transcriptionally activated the MAPK/Nrf2/GST pathway (Xu et al , ). In contrast to the effects of ES, gas stunning with CO 2 slightly suppressed the transcription of GSTA3, GSTT1 and SOD1 in the breast muscle but not in thigh muscle (Xu et al , ). These differences may be due to different biochemical and electrophysiological responses to CO 2 stunning and electrical stunning in thigh muscles of broilers.…”

“…1). Oppositely, CO 2 stunning slightly suppressed the transcription of JNK1 in the thigh muscle compared to no stunning (Xu et al, 2018b). At the downstream of MAPK/Nrf2 pathway, ARE is essential for the transcriptional induction of phase II enzymes, such as GST, NAD (P) H: quinone oxidoreductase 1 (NQO1) and heme oxygenase-1 (HO-1) (Jeong et al, 2016;Liang et al, 2018), which contribute to cytoprotection and potentially to the self-repair of cells exposed to oxidative stress (Kim & Lee, 2007).…”