Combined heat transfer and kinetic models to predict cooking loss during heat treatment of beef meat.

A heat transfer model was used to simulate the temperature in 3 dimensions inside the meat. This model was combined with a first-order kinetic models to predict cooking losses. Identification of the parameters of the kinetic models and first validations were performed in a water bath. Afterwards, the performance of the combined model was determined in a fan-assisted oven under different air/steam conditions. Accurate knowledge of the heat transfer coefficient values and consideration of the retraction of the meat pieces are needed for the prediction of meat temperature. This is important since the temperature at the center of the product is often used to determine the cooking time. The combined model was also able to predict cooking losses from meat pieces of different sizes and subjected to different air/steam conditions. It was found that under the studied conditions, most of the water loss comes from the juice expelled by protein denaturation and contraction and not from evaporation.

Kinetic analysis of cooking losses from beef and other animal muscles heated in a water bath--effect of sample dimensions and prior freezing and ageing.

Cooking loss kinetics were measured on cubes and parallelepipeds of beef Semimembranosus muscle ranging from 1 cm × 1 cm × 1 cm to 7 cm × 7 cm × 28 cm in size. The samples were water bath-heated at three different temperatures, i.e. 50°C, 70°C and 90°C, and for five different times. Temperatures were simulated to help interpret the results. Pre-freezing the sample, difference in ageing time, and in muscle fiber orientation had little influence on cooking losses. At longer treatment times, the effects of sample size disappeared and cooking losses depended only on the temperature. A selection of the tests was repeated on four other beef muscles and on veal, horse and lamb Semimembranosus muscle. Kinetics followed similar curves in all cases but resulted in different final water contents. The shape of the kinetics curves suggests first-order kinetics.

Design, operation, and modeling of a membrane photobioreactor to study the growth of the Cyanobacterium Arthrospira platensis in space conditions.

A membrane photobioreactor was designed, implemented and used to grow the cyanobacterium Arthrospira platensis PCC 8005 in batch mode. Growth was followed directly by monitoring optical density and indirectly by measuring pressure increase due to the oxygen produced and separated from the liquid phase by diffusion through a hydrophobic membrane, and pH increase due to carbon consumption. When the pressure attained an upper limit, valves opened automatically, and the oxygen in the gas chamber was flushed out with nitrogen. As expected, two growth phases were observed, a short exponential phase followed by a linear phase, indicating limitation by light transfer. Growth rate during the second phase was measured easily and accurately, and consistency of optical density, pressure and pH data values was checked using a model of the system. Pressure measurement was found best suited to monitoring and measuring growth rate in space in terms of accuracy, precision and reliability.

Uptake of macrominerals and trace elements by the cyanobacterium Spirulina platensis (Arthrospira platensis PCC 8005) under photoautotrophic conditions: culture medium optimization.

Uptake rates of macrominerals and trace elements were characterized in batch and continuous cultures of Spirulina platensis under photoautotropic conditions. The values of yield coefficients were determined using inductively coupled plasma emission spectroscopy (ICP-ES). Further simplifications of culture medium proved possible, mainly in the trace element solutions; concentrations of some elements were lowered and trace elements B, Mo, V, Cr, Ni, Co, W, and Ti were removed.