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Abstract
Fast or slow muscle pH fall may give unacceptable purge losses or tough meat, depending much on concomitant evolution of muscle temperature early post-mortem, costing millions of euros to the meat industry. Tenderness and purge losses of <em>Longissimus thoracis/lumborum</em> (<em>LTL</em>) and <em>Gluteus medius</em> (<em>Gm</em>) sampled from cull dairy cows differing in production status (10 lactating vs. 22 dried off) and aging time, were evaluated regarding different rates of pH<sub>2</sub> fall. Shear force related to pH<sub>2</sub> was dependent on muscle and aging time. The intermediate glycolysis led to lower shear force in <em>LTL</em>, while the faster produced best quality in <em>Gm</em>. Purge was influenced by pH<sub>2</sub> (P=0.0077), aging (P&lt;0.0001) and muscle*pH<sub>2</sub> interaction (P&lt;0.0001). Aging affected thawing (P&lt;0.0001), grilling (P=0.0004) and overall losses (P&lt;0.0001). Under the ruled chilling regime, the fast pH fall in <em>Gm</em> and the slow pH fall in <em>LTL</em> approached out of the ideal pH6/temperature limits, being compatible with heat and cold shortening, respectively.
Highlights
Meeting consumer requirements is a major concern for meat producers and retailers
Tenderness and purge losses of Longissimus thoracis/lumborum (LTL) and Gluteus medius (Gm) sampled from cull dairy cows differing in production status (10 lactating vs. 22 dried off) and aging time, were evaluated regarding different rates of pH2 fall
Since no additive effect in the glycolytic variation was objectively induced by cooling rate and considering the scored EUROP carcass classification (Table 1), which indicates that most of them would cool down at similar rates, the results show that the electrical stimulation response differed strongly among tested animals with normal muscle pH48 (Gm - between 5.76 and 5.38; LTL between 5.92 and 5.41) (Table 2)
Summary
Meeting consumer requirements is a major concern for meat producers and retailers. Retaining moisture and a high tenderness degree are considered important meat traits for consumer acceptability (Lonergan & Lonergan, 2005; Miller, Carr, Ramsey, Crockett, & Hoover, 2001). With the polarity inversion occurring in cell membranes at the early stages of the apoptosis process taking place in muscles after bleeding and O2 depletion (Ouali et al, 2006), the acidic components formed by glycolysis are replaced by others of basic nature, promoting partial neutralization and/or slowing down acidification, giving rise to transient “plateaus” in the pH fall dynamics (Herrera-Mendez, Becila, Boudjellal & Ouali, 2006). Partial denaturation of myosin head at low pH, namely when the muscle temperature is high, is thought to be a www.ccsenet.org/jfr
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