Xixiong Shi

To elucidate the mechanism underlying changes in the water-holding capacity of yak meat during postmortem aging, yak longissimus dorsi muscle was used as the experimental material. Changes in pressure loss, drip loss, cooking loss, and pH were determined at 0, 0.5, 1, 3, 5, and 7 d postmortem (0–4 °C; RH 80–85%). Proteomic approaches were employed to identify key proteins associated with water-holding capacity and the related metabolic pathways at representative aging stages. The results showed that the pressure loss, drip loss, and cooking loss of yak meat all exhibited an initial increase followed by a decrease during the 7 d postmortem aging period, reaching their maximum values at 3 d (42.10%, 3.19%, and 42.82%. p < 0.05). In contrast, pH displayed an opposite trend and declined to the minimum value of 5.35 at 3 d. Furthermore, proteomics analysis conducted at 0, 3 and 5 d of aging identified a total of 1239 proteins and screened 41 differentially expressed proteins. Through correlation analysis, 14 key proteins significantly associated with the WHC of yak meat were identified. Protein–protein interaction analysis indicated that Titin isoform X3, Calpastatin isoform I, and small muscular protein might serve as indicator proteins for the WHC of yak meat during aging. Most of these proteins are metabolic enzymes, structural proteins and stress proteins, which may influence meat quality by affecting the microstructure and metabolic pathways of the muscle.

Oula Tibetan sheep meat is rich in nutrients, but its tenderness is relatively poor. Therefore, exploring meat tenderization methods is crucial. Previous studies have indicated that reactive species generated by plasma promote mitochondrial dysfunction and induce apoptosis in tumor cells. However, the impacts of plasma treatment on mitochondrial pathway apoptosis and the tenderization of Oula Tibetan sheep meat have not been reported. This study aimed to explore the effects of cold atmospheric plasma (CAP) treatment on mitochondrial pathway apoptosis and meat tenderness of Tibetan sheep meat during postmortem aging. The results showed that after CAP treatment, reactive oxygen species (ROS) and nitric oxide (NO) content increased, pH value and ATP content decreased, resulting in an increase in mitochondrial permeability transition pore (MPTP) opening, a decrease in succinate dehydrogenase (SDH) activity, Cytochrome c (Cyt‐c) reduction level and mitochondrial membrane potential (MMP), and an increase in Caspase‐3/9 activity, promoting the occurrence of mitochondrial pathway apoptosis. Meanwhile, myofibril fragmentation index(MFI) increased, shear force value decreased and the mitochondrial structure was obviously damaged. The results of the correlation analysis showed that the degree of mitochondrial damage was significantly positively correlated with the tenderization of the meat during postmortem aging. Therefore, CAP treatment promoted mitochondrial pathway apoptosis and muscle tenderization during postmortem aging of Tibetan sheep meat by increasing the content of ROS and NO and altering the intracellular environment of muscle cells, thereby intensifying mitochondrial damage. The study can provide a theoretical basis for CAP treatment to improve the tenderness of Tibetan sheep meat. Practical Applications: The results of this study indicate that CAP treatment can improve the tenderness of Tibetan sheep meat by promoting apoptosis in the mitochondrial pathway. Therefore, CAP treatment may be used as a nonthermal processing technology to effectively improve the tenderness of Tibetan sheep meat.

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.

Pomegranate peel extract (PPE), rich in phenolic compounds, is an undervalued by-product during making pomegranate products. However, there are very few studies on the inhibitory of PPE on harmful substances during meat processing. This study was intended to investigate the influence of different contents of PPE (0.50%, 1% and 1.50%) on the generation of heterocyclic amines (HCAs) and some quality attributes in mutton meatballs. All samples with the addition of PPE (0, 0.50%, 1% and 1.50%) were fried for different time (2.5 and 5 min) at 175±5℃, and the contents of 14 HCAs, color, thiobarbituric acid reactive substances and carbonyls values of fried mutton meatballs were evaluated. The results showed that samples fried at 2.5 min had low contents of HCAs, and the contents of HCAs enhanced significantly when the frying time rose from 2.5 to 5 min (PPPa* values and b* values as well as decrease in L* values of fried mutton meatballs (P<0.05). In conclusion, PPE could inhibit the formation of HCAs and improve the quality of mutton meatballs, which could be considered as a kind of nature source to inhibit HCAs in fried meat products.

HSP27 and αβ‐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 αβ‐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 αβ‐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, αβ‐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 αβ‐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 αβ‐crystallin and meat quality reveals that HSP27 and αβ‐crystallin may contribute to the development of meat quality in Oula Tibetan sheep during postmortem aging. Therefore, HSP27 and αβ‐crystallin are effective research objects for regulating meat quality during postmortem aging.