Influence of ultimate pH (pHu) on the occurrence of defective meats known as dark, firm, and dry (DFD) meats has been studied through a proteomic approach at early post‐mortem times. The myofibrillar sub‐proteome of longissimus thoracis et lumborum muscle from twelve loin samples from Asturiana de los Valles x Friesian yearling bulls, previously classified into two groups of six samples according to their pH values (normal, pHu < 6.0 and high, pHu ≥ 6.0), is analyzed at 24 h post‐mortem. Fractionation/enrichment of muscle samples is carried out by combining OFFGEL fractionation in the pH range 4–7 followed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS‐PAGE) of the retrieved liquid fractions. Four protein bands satisfactorily discriminate between meat samples with normal and high pHu. These bands are quantified by image analysis, and further identified by liquid chromatography‐mass spectrometry as desmin, pyruvate kinase, myosin light chain, and myosin heavy chain‐1 and ‐2. Coupling OFFGEL and SDS‐PAGE separation with MS provides detailed and reproducible myofibrillar protein profiles enabling comparison among the sample groups assayed. This makes feasible to identify biomarkers capable to better understand pre‐slaughter stress condition susceptible to give DFD meats with high pHu values.

中文翻译：

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肌原纤维蛋白质组的表征，可以更好地理解具有不同最终pH值的牛肉中的差异。

已通过蛋白质组学方法在死后早期研究了最终pH（pHu）对缺陷肉（称为深色，硬和干（DFD）肉）的发生的影响。胸大肌和腰肌的肌原纤维亚蛋白质组在死后24小时对来自阿斯图里亚纳·德·洛斯·瓦雷斯x弗里斯兰一岁公牛的十二个腰部样本的肌肉进行分析，这些肌肉先前根据其pH值（正常，pHu <6.0和高，pHu≥6.0）分为两组，每组六个样本。通过结合pH范围为4-7的OFFGEL分馏和随后回收的液体馏分的十二烷基硫酸钠聚丙烯酰胺凝胶电泳（SDS-PAGE）进行肌肉样品的分馏/富集。在pHu正常和高pH的肉样品之间，四个蛋白质带可令人满意地区分。这些条带通过图像分析进行定量，并通过液相色谱-质谱法进一步鉴定为结蛋白，丙酮酸激酶，肌球蛋白轻链和肌球蛋白重链-1和-2。将OFFGEL和SDS-PAGE分离与MS结合使用可提供详细且可重现的肌原纤维蛋白谱，从而可在所分析的样品组之间进行比较。这使得鉴定能够更好地理解屠宰前应激状况的生物标记物成为可能，这些标记物容易使DFD肉具有高pHu值。