Inhibitory effects of longan seed extract on polycyclic aromatic hydrocarbons formation and muscle oxidation in baked mutton kebabs.

Longan seeds, rich in phenolic compounds with antioxidant properties, are an underestimated by-product of longan processing. Polycyclic aromatic hydrocarbons (PAHs), which are carcinogenic and mutagenic, are produced during the cooking of meat products at high temperatures. The effects of different concentrations of longan seed extract (LSE, 0.2, 0.6, 1.0 mg/mL) on the formation of PAHs and muscle oxidation in mutton kebabs were investigated. Mutton kebabs were baked at 150, 200, 250 °C for 20 min, respectively, and the contents of PAHs, the degree of lipid and protein oxidation were evaluated. The results showed that LSE exhibited positive effects in inhibiting total PAHs formation (range from 14.9 to 48.8 %), decreasing the thiobarbituric acid reactive substances (TBARS) values (range from 17.1 to 39.1 %), reducing carbonyl content (range from 22.0 to 51.2 %) and increasing sulfhydryl content (range from 18.6 to 51.8 %). This study provided a guidance and potential solution for reducing the content of PAHs and muscle oxidation levels in baked meat.

Preparation of Bovine Hides Gelatin by Ultra-High Pressure Technique and the Effect of Its Replacement Fat on the Quality and In Vitro Digestion of Beef Patties.

Beef skin gelatin can be used as a good substitute for animal fat in meat patties. In this paper, the effect of different parameters on low-fat beef patties with cowhide gelatin substituted for beef fat (0, 25%, 50%, 75%, 100%) prepared by ultra-high pressure assisted technology was investigated by texture, cooking loss, and sensory scores. The beef patties were also stored at 0-4 °C for 0, 7, 14, 21, and 28 d. The differences and changing rules of fatty acid and amino acid compositions and contents of beef patties with different fat contents were investigated by simulating gastrointestinal digestion in vitro. The optimal process formulation of low-fat beef patties with cowhide gelatin was determined by experimental optimization as follows: ultra-high pressure 360 MPa, ultra-high of pressure time of 21 min, NaCl addition of 1.5%, compound phosphate addition of 0.3%. The addition of cowhide gelatin significantly increased monounsaturated fatty acids, polyunsaturated fatty acids, amino acid content, and protein digestibility of beef patties (p < 0.05). Moreover, with the extension of storage time, the content of saturated fatty acids was significantly higher (p < 0.05), the content of monounsaturated and polyunsaturated fatty acids was significantly lower (p < 0.05), the content of amino acids was significantly lower (p < 0.05), and protein digestibility was significantly lower (p < 0.05) under all substitution ratios. Overall, beef patties with 75% and 100% substitution ratios had better digestibility characteristics. The results of this study provide a theoretical basis for gelatin's potential as a fat substitute for beef patties and for improving the quality of low-fat meat products.

H2O2-induced oxidative stress improves meat tenderness by accelerating glycolysis via hypoxia-inducible factor-1α signaling pathway in postmortem bovine muscle.

Reactive oxygen species (ROS) affect meat quality through multiple biochemical pathways. To investigate the effect of ROS on postmortem glycolysis and tenderness of bovine muscle, ROS content, glycolytic potential, glycolysis rate-limiting enzyme activities, expression of hypoxia-inducible factor-1α (HIF-1α), phosphatidylinositol 3-kinase (PI3K), serine-threonine kinase (AKT), phosphorylated AKT (p-AKT), and tenderness were determined in the H2O2 group and control group. Results showed that the H2O2 group exhibited significantly higher ROS content within 48 h, coupled with increased glycolytic potential, pH decline, hexokinase (HK), and phosphofructokinase activities (PFK) early postmortem. These were attributed to ROS-induced PI3K/AKT signaling pathway activation and resultant HIF-1α accumulation. Moreover, shear force in the H2O2 group reached the peak 12 h earlier and decreased obviously after 24 h, accompanied by a significantly higher myofibril fragmentation index (MFI). These findings suggested that ROS drive HIF-1α accumulation by activating PI3K/AKT signaling pathway, thereby accelerating glycolysis and tenderization of postmortem bovine muscle.

Effects of nitric oxide synthase inhibitor on mitochondria apoptosis and meat quality in postmortem Gannan yak (Bos grunniens) meat.

This research aimed to explore the effects of the nitric oxide synthase (NOS) inhibitor (L-NAME) on mitochondria apoptosis in postmortem Gannan yak (Bos grunniens) longissimus dorsi (LD) muscle and to explore its effect on meat quality further. The Gannan yak meat samples were treated with the control group (0.9% NaCl) and L-NAME (20, 60, and 100 mM) for 24 h and then stored for 0, 1, 3, 5, and 7 days at 4°C. NOS activity and NO content were investigated, and the parameters of mitochondrial apoptosis of the postmortem Gannan yak meat were determined. Meanwhile, the meat quality such as the centrifugation loss, meat color, and myofibril fragmentation index (MFI) was evaluated. The results indicated that after treatment with L-NAME, NOS activity and NO content decreased, causing mitochondrial membrane damage, Bax protein, and Cyt-c levels increased, and resulted in increased activities of caspase-9 and -3, promoting the occurrence of mitochondrial apoptosis. Furthermore, it increased the tenderness and water retention of Gannan yak meat. The results indicated that NOS inhibitor played a regulatory role in postmortem Gannan yak meat quality by regulating mitochondria apoptosis during postmortem aging. PRACTICAL APPLICATIONS: The meat's tenderness is often considered the most important factor affecting consumers' willingness to repurchase. The relationship of caspases and MFI suggested that L-NAME played a regulatory role in postmortem Gannan yak meat quality by regulating mitochondria apoptosis during postmortem aging. This study provides valuable information for the development of the Gannan yak economy in Tibetan areas.

Influence of Tissue Type on the Bacterial Diversity and Community in Pork Bacon.

In current study, bacterial diversity and community in different tissues of pork bacon were determined using high-throughput sequencing. In total, six phyla and 111 bacterial genera were identified. Among them, three dominant genera (Staphylococcus, Acinetobacter, and Macrococcus) were shared by all bacon samples. The linear discriminant analysis showed that 24 bacterial taxa significantly differentiated between the tissues. Results of non-metric Multidimensional Scaling and redundancy analysis showed that physicochemical characteristics of the tissue prominently structured the bacterial communities. Network analysis also illustrated that tissue type was an important factor impacting the bacterial interactions in different types of tissue. The results of current study can add valuable insights to the traditional homemade pork bacon.

Concentrations of HSP27 and αß-crystallin in Oula Tibetan sheep meat and their relationship with meat quality during postmortem aging.

HSP27 and αß-crystallin are molecular chaperones participating in multiple cellular processes. Their roles in the development of postmortem meat quality remain unclear. The current study was designed to investigate the relationship between the concentrations of HSP27 and αß-crystallin with meat quality during postmortem aging. Specifically, cooking loss, color, pH, and the myofibril fragmentation index (MFI) of Oula Tibetan sheep meat were determined, and changes in the concentrations of HSP27 and αß-crystallin were evaluated. The results indicated that HSP27 concentration significantly decreased in 0-3 days (p < 0.05), presenting a positive correlation with pH (p < 0.05) and a negative correlation with L*, b*, cooking loss, and MFI (p < 0.05, p < 0.05, p < 0.01, p < 0.01). Besides, αß-crystallin concentration significantly decreased in 0-2 days (p < 0.05), exhibiting a significant positive correlation with pH (p < 0.05) and a negative correlation with L*, b*, cooking loss, and MFI (p < 0.01, p < 0.01, p < 0.01, p < 0.01). The results suggested that the HSP27 and αß-crystallin may participate in the development of meat quality in Oula Tibetan sheep during postmortem early aging. PRACTICAL APPLICATION: Tenderness, color, and water holding capacity (WHC) are crucial quality attributes of meat. The relationship between the concentrations of HSP27 and αß-crystallin and meat quality reveals that HSP27 and αß-crystallin may contribute to the development of meat quality in Oula Tibetan sheep during postmortem aging. Therefore, HSP27 and αß-crystallin are effective research objects for regulating meat quality during postmortem aging.

Effect of oxidative stress on AIF-mediated apoptosis and bovine muscle tenderness during postmortem aging.

This study aimed to explore the effect exerted by oxidative stress on apoptosis-inducing factors (AIF)-mediated apoptosis and bovine muscle tenderness during postmortem aging. We investigated the reactive oxygen species (ROS) content, mitochondrial membrane permeability, AIF expression level, nucleus apoptosis, shear force, myofibril fragmentation index, pH, and energy level. According to the results, a rise in ROS content was accompanied by the rise in mitochondrial membrane permeability from 6 to 72 hr. In the meantime, the AIF expression in mitochondria was downregulated significantly within 72 hr. However, samples treated with N-acetylcysteine had significantly lower ROS content (6 to 72 hr) and mitochondrial membrane permeability (12 to 72 hr) than the control group. Moreover, during postmortem aging, the variations in AIF levels in mitochondria were closely associated with meat tenderization and nucleus apoptosis. These findings demonstrated that oxidative stress induced by ROS significantly promoted AIF release from mitochondria by enhancing the mitochondrial membrane permeability, and the released AIF mediated nucleus apoptosis that further enhanced bovine muscle tenderness. Besides, results suggest that in the early stage, the environmental factors (ATP content and pH) significantly decreased (0 to 72 hr), whereas ROS-induced oxidative stress had no significant effect on environmental factors. These observations further suggested that during postmortem aging, the decrease of pH and ATP consumption are required by AIF release. We conclude that ROS-induced oxidative stress and internal environment are vital for meat tenderization through the regulation of AIF-mediated apoptosis pathway. PRACTICAL APPLICATION: ROS-induced oxidative stress contributes to bovine muscle tenderization by promoting cell apoptosis. It is likely to lay a theoretical foundation for developing innovative tenderization techniques by altering the internal oxidation environment of postmortem muscles.

Effect of mitochondrial cytochrome c release and its redox state on the mitochondrial-dependent apoptotic cascade reaction and tenderization of yak meat during postmortem aging.

We aim to investigate the effect of mitochondrial cytochrome c release and its redox state on the mitochondrial-dependent apoptotic pathway and yak meat tenderization during postmortem aging. Results indicated that the internal environment factors considerably decreased, whereas mitochondrial dysfunction increased in the early stage (0-72 h). Moreover, the release of mitochondrial cytochrome c into the cytosol, which was an apoptotic early event and the apoptosome elements in the cytoplasm changed remarkably with the increase of aging time. Meanwhile, N,N,N',N'-tetramethylphenylene-1, 4-diamine (TMPD) inhibited the mitochondrial apoptotic process and postmortem meat tenderization by influencing the redox state of cytochrome c and apoptotic factors. These findings confirmed that the internal environment factors in the muscles provided essential conditions for mitochondrial cytochrome c, which activated the mitochondrial apoptotic pathway by forming apoptosome complexes. The reduction state of cytochrome c produced by TMPD plays a negative role in the activation of the mitochondrial apoptotic cascade reaction and meat tenderization during postmortem aging. We conclude that mitochondrial cytochrome c release and oxidized cytochrome c plays a significant role in yak meat tenderization by regulating the mitochondrial apoptotic pathway.