Understanding Early Post-Mortem Biochemical Processes Underlying Meat Color and pH Decline in the Longissimus thoracis Muscle of Young Blond d’Aquitaine Bulls Using Protein Biomarkers

Abstract

Many studies on color biochemistry and protein biomarkers were undertaken in post-mortem beef muscles after ≥24 hours. The present study was conducted on Longissimus thoracis muscles of 21 Blond d'Aquitaine young bulls to evaluate the relationships between protein biomarkers present during the early post-mortem and known to be related to tenderness and pH decline and color development. pH values at 45 min, 3 h, and 30 h post-mortem were correlated with three, seven, and six biomarkers, respectively. L*a*b* color coordinates 24 h post-mortem were correlated with nine, five, and eight protein biomarkers, respectively. Regression models included Hsp proteins and explained between 47 and 59% of the variability between individuals in pH and between 47 and 65% of the variability in L*a*b* color coordinates. Proteins correlated with pH and/or color coordinates were involved in apoptosis or had antioxidative or chaperone activities. The main results include the negative correlations between pH45 min, pH3 h, and pHu and Prdx6, which may be explained by the antioxidative and phospholipase activities of this biomarker. Similarly, inducible Hsp70-1A/B and μ-calpain were correlated with L*a*b* coordinates, due to the protective action of Hsp70-1A/B on the proteolytic activities of μ-calpain on structural proteins. Correlations existed further between MDH1, ENO3, and LDH-B and pH decline and color stability probably due to the involvement of these enzymes in the glycolytic pathway and, thus, the energy status of the cell. The present results show that research using protein indicators may increase the understanding of early post-mortem biological mechanisms involved in pH and beef color development.

Differences in Beef Quality between Angus (Bos taurus taurus) and Nellore (Bos taurus indicus) Cattle through a Proteomic and Phosphoproteomic Approach

“…In agreement with this, HSPA9 level in muscle after slaughter had negative correlation with both pH at 3 hours and ultimate pH in the cattle carcass, and it was proposed that this result would be associated with an increased release of Ca 2+ from the sarcoplasmic reticulum and, consequently, with higher enzyme activity and rigor mortis [49]. A positive relation found between μ-calpain and HSPA9 through correlation networks among protein biomarkers of beef tenderness also support our hypothesis [50].…”

Calcium Homeostasis and Muscle Energy Metabolism Are Modified in HspB1-Null Mice

“…It plays a key role in the folding of matrix-localized mitochondrial proteins and in the transport of proteins into the mitochondrion [36]. In cattle meat, HspA9 was related to pH3h postmortem , ultimate pH (pHu), and L* and b* color coordinates [37]. It plays a role in Ca 2+ trafficking from the SR to the sarcoplasm, which may also explain relationship between HspA9 and the enzymes of the glycolytic pathway described by Gagaoua et al [16] in cattle.…”

Sensory quality of meat from eight different types of cattle in relation with their biochemical characteristics

“…They depend on the 25 contractile and metabolic properties of the different categories of the myofibres (type I, type 26 IIa, type IIx and/or type IIb) that compose the bovine skeletal muscles 2009) and on the attachment of these fibres to the intramuscular connective tissues (IMCT) of 28 which collagen is the major protein component (Nishimura 2010;Dubost et al 2013). Muscle 29 fibre composition is known to influence colour, tenderness and ultimate pH (Muchenje et al 30 2009; Wu et al 2014;Gagaoua et al 2015a) and intramuscular fat (IMF) content is believed to 31 influence tenderness and juiciness (Mandell et al 1997;Scollan et al 2001;Gagaoua et al 32 2014).…”

“…Ultimate pH was recorded between the 6 th and 7 th rib using a pH meter equipped with a glass 336 electrode 24h or 48 h post-mortem (Gagaoua et al 2015a). …”