Cooking & boiling in meat production
General introduction for grilling
It involves dry heat applied to the surface of food, commonly from above or below. Grilling usually involves a significant amount of direct, radiant heat, and tends to be used for cooking meat quickly. Heat transfer to the food when using a grill is primarily via thermal radiation. Internal temperature of the meat should be about between 55oC and 75oC. Heat transfer when using a grill pan or griddle is by direct conduction. Direct heat grilling can expose food to temperatures often in excess of 260°C. The fat and juices are lost by grilling and can contribute to drier food. The internal temperature is a function of (i) thickness of the meat, and (ii) how well cooked the meat should be (e.g. rare, medium, medium-rare, well-done). It has been advised to take the meat out from the grill once the desired internal temperature is achieved.
General introduction for steaming
Steaming works by boiling water continuously, causing it to vaporize into steam; the steam then carries heat to the nearby food, thus cooking the food. The food is kept separate from the boiling water but has direct contact with the steam, resulting in a moist texture to the food. Overcooking or burning food is easily avoided when steaming it. Steaming also results in a more nutritious food than boiling because fewer nutrients are leached away into the water, which is usually discarded.
General introduction for stewing
A stew is a combination of solid food ingredients that have been cooked in liquid and served in the resultant gravy. Stew and soup are roughly similar, the only difference is their water content, being higher in soup (boiling temperature may be needed), while the stewing usually requires longer cooking time at lower temperature, i.e. ~79–93°C. Ingredients in a stew can include any combination non-meat ingredients which can make it a bit difficult to identify the total energy requirement for stewing/soup making. Stewing is suitable for the least tender cuts of meat that become tender and juicy with the slow moist heat method. This makes it popular in low-cost cooking. Cuts having a certain amount of marbling and gelatinous connective tissue give moist, juicy stews, while lean meat may easily become dry.
General introduction for frying
It is a cooking method in which food is submerged in hot fat e.g. oil. Deep frying is classified as a dry cooking method because no water is used. Due to the high temperature involved and the high heat conduction of oil, it cooks food extremely quickly. If performed properly, deep-frying does not make food excessively greasy, because the moisture in the food repels the oil. The hot oil heats the water within the food thus vaporising the water into steam for which oil cannot go against. As long as the oil is hot enough and the food is not immersed in the oil for too long, oil penetration will be confined to the outer surface. If the food is cooked in the oil for too long, much of the water will be lost and the oil will begin to penetrate the food. The correct frying temperature depends on the thickness and type of food, but in most cases it lies between 175–190 °C.
Shallow-fried foods are often battered. The food is only partly submerged and must be turned over partway through the cooking process. This causes the increase in cooking time.
Energy savings can be achieved through the steam generated during the frying process being condensed and the released energy being used to heat water.
Thermal diffusivity of meat
If meat is cooked the core of the meat must reach the desired temperature. The time for this process is influenced - besides others - by the thermal diffusivity.