The effects of preparation and heat to meat

a) Tenderness
Meat that is difficult to cut or hard to chew is said to be tough. It has longer and thicker muscle fibres. The meat of older animals – for example, mutton, beef and part of an animal that are used a lot – have long, thick fibres, like the neck muscle of the sheep.
The amount of connective tissue has a bearing on tenderness. Tough meat has more connective tissues than tender meat. This too is related to the age of the animal and the activity of the muscles.
Certain procedures in food preparation can increase the tenderness of tough meat. The muscle fibres and connective tissues may be broken by mechanical action, as in mincing or bashing with a rolling pin or meat hammer.
Proteolytic enzymes may be used to digest muscle fibres and connective tissue partially. Commercially prepared tenderisers may be used or enzymes obtained directly from their sources, including papain from the leaves of pawpaw.
When proteolytic proteins are used it is important to allow the penetration of the enzymes. Also, timming is critical: if the treatment is done the meat will have a crumby texture and an unpleasant flavour.
Substances that increase the hydration or water holding capacity of the muscle-fibre proteins may be used as tenderiser, and these include acids, alkalis, and salt. Acids like in lemon juice, vinegar, wine and tomatoes may be used.
Cooking also affect tenderness. As a result of cooking the muscle fibre proteins coagulate and water is lost. This accounts for much of the shrinkage of the cooked meat.
- Dry methods of cooking such as roasting and grilling cause rapid shrinkage and toughening of the tissue. Such cooking method is suitable for soft tender cuts.
- When moist method of cooking such as stewing and braising are used the shrinkage and toughening occur more slowly therefore these methods of cooking are more suitable for tough cuts of meat.
Initially during cooking the collagen in the connective tissues shrinks, and this causes the meat to ‘lump’. This can be seen in the preliminary frying in the preparation of a brown stew. With further cooking the collagen is converted to gelatine. The formation of gelatine is enhanced by moist method of cooking. This is particularly important for tough cuts of meat which have more collagen that tender cuts. Evidence of gelatine formation which can be seen when cooking liquids from tough cuts of meat have cooled. These liquid solidify because of the gel formed.
The fats melts, and this contribute to the shrinkage of cooked meat. In dry methods of cooking, such as grilling and roasting, the melted fats prevent the meat from becoming dry. In moist method the fats floats to the top of the liquid and can be skimmed off.

b) Flavour
The flavour of meat is largely due to the extractives and fat. Flavour is more pronounced in less tender cuts of meat. Muscle from older animals or well-exercised parts have more extractives than the muscle of young animals or less-used part. Extractives are believed to contain soluble inorganic salt, lactic acid and nitrogenous compounds.
Fat has a distinct effect on the flavour and aroma of meat. The aroma from fat during cooking is largely responsible for the smells associated with different meats.
In dry method of cooking the extractives and fat settle on the surface of the meat. This is why the meat on the outside of a joint is more tasty than the interior. In moist methods of cooking, the extractives and fat pass into the cooking liquid, so unless this is used in the recipe as a source to accompany the dish much of the flavour will be lost.
There is an association between the flavour and cooking time. If less tender cuts of a beef are cooked in a pressure cooker or a microwave oven, the flavour is not so well developed as in beef cooked by longer, more conventional methods.

c) Colour
The colour of the meat is mainly due to the pigment myoglobin. This pigment accounts for about 75% of the total pigment of the red meat. Some muscles contain more of this pigment than others; for example, leg of chicken is darker than the breast because of its myoglobin content. Well-used muscle and older animals are darker.
The colour of meat changes during cooking. When heated the pigment myoglobin is oxidised to form oxymyoglobin. This is associated with change in colour from purple-red to bright red. With further heating the meat becomes greyish brown due to the formation of denatured globin hemichrome. Here the protein in the protein is denatured and the iron in the pigment is oxidised.

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Titany answered the question on April 25, 2022 at 12:03