Temperature and pH of meat during chilling are important variables affecting final meat quality.A computational fluid dynamics (CFD) model was developed to predict the changes in temperature and pH distribution of a beef carcass during chilling. The model was solved using the 3D geometry of the carcass side obtained by digital scanning and including post-mortem reaction kinetics. The cooling simulation accounted for both the slaughter floor environment and the chiller room conditions. A three-step approach was followed for the chiller room simulation.In the first step, a steady state simulation of the airflow and thermal field around the carcass was done. From this simulation, local convective transfer coefficients (CTCs) on the carcass surface were determined in a second step. In the third step, these CTCs were used to perform a transient heat conduction simulation within the carcass itself, including also glucose conversion, pH evolution and internal heat production. Carcass temperatures at various depths and sections were measured during a chilling experiment of a single carcass for model validation with air velocity, temperature and relative humidity as inputs for the CFD model. The temperature predictions agreed with the measured temperature profiles at different positions inside the carcass, with excellent prediction in deep positions of the hindquarter as compared to near surface positions.The simulations unveiled large difference in cooling rates and pH evolution between different parts of the carcass that could lead to differences in meat quality by heat shortening. The model can be used to study the effect of relevant cooling parameters on the rate and uniformity of cooling and meat quality.
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.
Precooling has been questioned as a suitable step in the process of beef carcass cooling. Model‐based optimization was performed to identify optimum operating conditions for different heavy‐muscled beef carcass cooling practices in slaughterhouses with both precooling and cooling stages. The study was conducted using a validated computational fluid dynamics model of the beef carcass cooling process. The precooling practice was optimized based on a weighted impact function taking into account energy consumption, weight loss, cooling time, and heat shortening duration. The values of these output variables were dependent on air temperature, air velocity, and precooling time. The results clearly show the benefit of using a precooling unit that operates with an optimum precooling time, cooling air temperature, and velocity. Using a weighted impact function of energy cost and quality, a precooling time of 4 hr using −30°C but low air velocity (0.58 m s−1) appeared more beneficial than precooling using high airflow fans with high energy consumption. The eventual optimum operation conditions depend on the impact variable that the operator wants to minimize and is a trade‐off between adverse effects on energy use and meat quality. Practical applications The comprehensive computational fluid dynamics model can be applied to optimize the operation and design of carcass precooling system. Carcass cooling system operators can make a choice of the impact variable they want to minimize and use the approach to determine the optimum operating condition of the cooling system. The approach can be applied to develop carcass cooling procedure that could potentially minimize the energy consumption and maximize the quality of the carcass.
High-temperature structural ceramic materials require stability in terms of thermal and mechanical properties. High entropy oxides (HEOs) are among the emerging novel family of advanced ceramic materials with peculiar functional properties. However, their thermal stabilities and mechanical properties are not well investigated. In this work, HEO systems were synthesized from binary oxides of MgO, CoO, NiO, CuO, and ZnO using solid-state reaction method at high temperature, after obtaining the individual oxides through co-precipitation methods. The phase purity of as-synthesized and sintered samples was characterized using X-ray powder diffraction, while the microstructural investigation was performed using Scanning electron microscopy. Mechanical property of the sintered samples at different sintering times and temperatures was investigated and the sample sintered at a sintering temperature of 1200 °C for 15 h sintering time showed a maximum Vickers hardness of about 16 GPa. This result is comparable with some of the hard ceramic materials, and therefore the materials could be a potential candidate for structural applications.
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