Muroya Susumu, Oe Mika, Ojima Koichi, Watanabe Akira
Muscle Biology Research Unit, Animal Products Research Division, NARO Institute of Livestock and Grassland Science, Tsukuba, Ibaraki 305-0901, Japan.
NARO Tohoku Agricultural Research Center, Morioka, Iwate 020-0198, Japan.
Asian-Australas J Anim Sci. 2019 Aug;32(8):1172-1185. doi: 10.5713/ajas.18.0648. Epub 2019 Jan 4.
Meat quality attributes in postmortem muscle tissues depend on skeletal muscle metabolites. The objective of this study was to determine the key metabolic compounds and pathways that are associated with postmortem aging and beef quality in Japanese Black cattle (JB; a Japanese Wagyu breed with highly marbled beef).
Lean portions of Longissimus thoracis (LT: loin) muscle in 3 JB steers were collected at 0, 1, and 14 days after slaughter. The metabolomic profiles of the samples were analyzed by capillary electrophoresis time-of-flight mass spectrometry, followed by statistical and multivariate analyses with bioinformatics resources.
Among the total 171 annotated compounds, the contents of gluconic acid, gluconolactone, spermidine, and the nutritionally vital substances (choline, thiamine, and nicotinamide) were elevated through the course of postmortem aging. The contents of glycolytic compounds increased along with the generation of lactic acid as the beef aging progressed. Moreover, the contents of several dipeptides and 16 amino acids, including glutamate and aromatic and branched-chain amino acids, were elevated over time, suggesting postmortem protein degradation in the muscle. Adenosine triphosphate degradation also progressed, resulting in the generation of inosine, xanthine, and hypoxanthine via the temporal increase in inosine 5'-monophosphate. Cysteine-glutathione disulfide, thiamine, and choline increased over time during the postmortem muscle aging. In the Kyoto encyclopedia of genes and genomes database, a bioinformatics resource, the postmortem metabolomic changes in LT muscle were characterized as pathways mainly related to protein digestion, glycolysis, citric acid cycle, pyruvate metabolism, pentose phosphate metabolism, nicotinamide metabolism, glycerophospholipid metabolism, purine metabolism, and glutathione metabolism.
The compounds accumulating in aged beef were shown to be nutritionally vital substances and flavor components, as well as potential useful biomarkers of aging. The present metabolomic data during postmortem aging contribute to further understanding of the beef quality of JB and other breeds.
宰后肌肉组织中的肉质属性取决于骨骼肌代谢物。本研究的目的是确定与日本黑牛（JB；一种具有高度大理石花纹牛肉的日本和牛品种）宰后成熟和牛肉品质相关的关键代谢化合物和途径。
在3头JB阉牛屠宰后0、1和14天收集胸最长肌（LT：腰部）的瘦肉部分。通过毛细管电泳飞行时间质谱分析样品的代谢组学谱，随后使用生物信息学资源进行统计和多变量分析。
在总共171种注释化合物中，葡萄糖酸、葡萄糖酸内酯、亚精胺以及营养必需物质（胆碱、硫胺素和烟酰胺）的含量在宰后成熟过程中升高。随着牛肉成熟的进展，糖酵解化合物的含量随着乳酸的产生而增加。此外，随着时间的推移，包括谷氨酸以及芳香族和支链氨基酸在内的几种二肽和16种氨基酸的含量升高，表明肌肉中存在宰后蛋白质降解。三磷酸腺苷降解也在进行，通过5'-单磷酸肌苷的暂时增加导致肌苷、黄嘌呤和次黄嘌呤的产生。半胱氨酸-谷胱甘肽二硫化物、硫胺素和胆碱在宰后肌肉成熟过程中随时间增加。在生物信息学资源京都基因与基因组百科全书数据库中，LT肌肉的宰后代谢组学变化被表征为主要与蛋白质消化、糖酵解、柠檬酸循环、丙酮酸代谢、磷酸戊糖代谢、烟酰胺代谢、甘油磷脂代谢、嘌呤代谢和谷胱甘肽代谢相关的途径。
老龄牛肉中积累的化合物被证明是营养必需物质和风味成分，以及衰老的潜在有用生物标志物。目前宰后成熟过程中的代谢组学数据有助于进一步了解JB和其他品种的牛肉品质。
