Modelling postmortem evolution of pH in beef M. biceps femoris under two different cooling regimes

Abstract

A model based on enzyme kinetics was developed to predict differences in postmortem pH change in beef muscles as affected by cooling rate. For the calibration and validation of the model, pH and temperature measurements were conducted at different positions in following conventional carcass cooling or faster cooling of the muscle after hot boning. The glycogen conversion, and, hence, the pH fall, was observed to significantly vary with position and cooling regime but only during the initial hours of cooling. Comparison of the cooling regimes indicated that fast cooling following hot boning avoids heat shortening induced by the combined effect of high temperature and low pH.

Optimizing precooling of large beef carcasses using a comprehensive computational fluid dynamics model

“…Particularly, the thin areas of the carcases (such as longissimus dorsi ) are highly susceptible to freezing. Heat is generated inside the carcass side due to enzymatic reactions (Kuffi et al, ). The energy balance inside the carcass then becomes: where ρ c (kg m −3 ), c pc (J kg −1 °C −1 ), T (°C), λ c (W m −1 °C −1 ), and t (s) are carcass density, heat capacity, temperature, thermal conductivity, and time, respectively.…”

“…The term d [G]/ dt (mol m −3 s −1 ), r is constant (1.25) and Δ H ATP (J per mol of ATP hydrolyzed) are the glucose conversion rate and enthalpy change during ATP hydrolysis, respectively. More details about the determination of the glucose conversion rate and the energy source can be found in Kuffi et al (, ). The glucose conversion rate, d [G]/ dt , in postmortem muscle was expressed in the form of a rate limiting model using a Michaelis–Menten equation, where the constant values in the equation were fitted based on pH–temperature–time data obtained from 59 Belgian Blue beef carcasses as explained in Kuffi et al (). where [G] (mol m −3 ) is the unconverted glucose concentration, V max,ref (mol m −3 s −1 ) is the maximum conversion rate of the reaction at reference temperature, T ref (°C), equal to 37°C, T is the temperature (°C), K m (mol m −3 ) the Michaelis–Menten constant, K a (mol m −3 ) is the acid dissociation constant and [H + ] is the hydrogen ion concentration.…”

“…Cooling of beef carcasses after slaughtering is an important process to maintain the safety and quality of beef (Cepeda, Weller, Negahban, Subbiah, & Thippareddi, ; Hamoen, Vollebregt, & Van Der Sman, ; Jacob & Hopkins, ; Kuffi et al, , ). Cold air blast cooling is the most commonly used method of beef carcass cooling and the cooling characteristics depend on the cooling air temperature, velocity, relative humidity, and carcass characteristics (geometry, thermophysical properties, rate of biochemical reactions, and orientation relative to the airflow direction; Kuffi et al, ; Mirade, Kondjoyan, & Daudin, ; Mirade & Picgirard, ; Pham, Trujillo, & McPhail, ; Trujillo & Pham, ; van der Wal, Engel, van Beek, & Veerkamp, ).…”

“…The objective of this study was to identify the optimum working conditions during beef carcass precooling using a model‐based optimization of the beef carcass cooling process with the validated 3D CFD model of Kuffi et al (, ). Different objectives were compared: Equal balancing of the demands of energy consumption, quality and cooling time Minimizing energy consumption of cooling Minimizing quality loss (weight loss and heat shortening) Minimizing cooling time …”

“…In case of big carcasses, such as those of Belgian Blue bulls with an eviscerated carcass weight of >500 kg (Fiems, De Campeneere, Van Caelenbergh, De Boever, & Vanacker, 2003), it could be questioned whether the short precooling assists the required temperature drop to avoid muscle shortening (Kuffi et al, 2017). Unless it is properly controlled, it has been reported that both high and low cooling rates have adverse effects on the quality of beef carcasses, which is associated to cold and heat shortening, respectively (Thompson, 2002).…”