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Meat

The nutritional value and biochemical structure of meat

Meat is an important source of high-quality protein with a high biological value. Proteins make up 18–22 % of the total mass of muscle tissue. They are notable for the fact that their composition contains all the amino acids in optimal proportions for the synthesis of the body's own proteins. Muscle proteins are divided into two fractions: a soluble fraction (myogen, myoglobulin and alpha-globulin) and an insoluble fraction, represented by myosin and actin. When meat is cooked, the soluble proteins pass into the cooking liquid; they give the meat its organoleptic properties: taste, smell, colour.

Meat contains varying amounts of lipids. The fat in its composition increases the calorie value and makes it filling. Meat lipids are rich in saturated fatty acids, particularly in mammals. In the flesh of fish, we find a higher proportion of unsaturated fatty acids in the composition of the lipids compared with saturated ones.

The carbohydrates in meat are represented by glycogen and occur only in small amounts. Compared with other kinds of meat, horse meat contains slightly more glycogen, which gives it a sweet taste.

The protein, carbohydrate and lipid content of meat depends on the species of animal, its age, its sex, its living conditions (wild or domesticated), its nutritional state and the anatomical area it comes from.

Meat is a rich source of minerals and vitamins. Among the minerals, we should mention the presence of phosphorus, iron, sodium and potassium in higher proportions in the meat of various mammal species. We should also mention the flesh of fish as an important source of iodine and fluoride.

As far as vitamin content is concerned, meat is notable for its predominance of B group vitamins (B1, B2, B3 – PP, B5 – pantothenic acid, B6, B9 – folic acid, B12). Pork is richer in thiamine.

The oil obtained from the liver of some species of fish (fish oil) is an important source of vitamins A and D.

Besides its nutritional function, meat also has the job of stimulating digestive secretion through a range of substances that pass into the boiling water (broth) when the meat is cooked and have a strong secretion-stimulating effect on the digestive juices.

Because of its nutritional properties, meat is indispensable in the diet of healthy people of all ages, but also during convalescence, under heavy strain, for children and adolescents, for pregnant and breastfeeding women and for people who exert themselves a great deal.

The meat of farm animals is characterised as follows:

  • horse meat and lamb have the highest protein content, pork the lowest
  • The highest proportion of lipids is found in mutton and pork, the lowest in horse meat. In general, the proportion of fat and connective tissue increases as the animal gets older, which changes the appearance, tenderness and digestibility of the meat.
  • Among the vitamins, thiamine is present in raised amounts in pork, and vitamin PP is present in raised amounts in all mammal species;
  • Among the mineral salts, phosphorus is found in greater amounts in veal and rabbit and potassium in mutton and pork. Horse meat provides important amounts of iron and sodium.

Farmyard poultry is characterised as follows:

  • the highest protein content is found in chicken and turkey;
  • The highest proportion of lipids is found in duck and goose;
  • As far as digestibility is concerned, chicken is better than duck or goose.

Fish fats stand out for their high proportion of polyunsaturated fatty acids (they are liquid at normal temperature – fish oil). The omega-3 fatty acids EPA and DHA contribute to the normal function of the heart (with a daily intake of 250 mg), and DHA also to the maintenance of normal brain function.

The flesh of fish is also rich in vitamins A and D and low in thiamine (because of an enzyme that destroys it); it also has a raised content of iodine and fluorine. Fish is easy to digest, but it spoils very quickly and requires special storage conditions.

The flesh of amphibians and aquatic invertebrates is notable for its high water content and high-quality proteins. It contains considerable amounts of vitamins A, B1 and B2 and minerals – phosphorus, potassium, iron.

Offal (entrails and organs) means all the edible parts of the animal, apart from the carcass, that are obtained by gutting. There are two categories: red (liver, spleen, kidneys, heart, tongue, lungs) and white (brain, pancreas, salivary glands, intestines, stomach, bone marrow).

The liver is rich in proteins, glycogen, minerals (iron, phosphorus, copper and so on) and vitamins. The heart is rich in some minerals: potassium, iron, phosphorus.

Brain and bone marrow contain considerable amounts of phosphorylated lipids, but only small amounts of protein. Their structure contains large amounts of vitamins and minerals – phosphorus (the largest amount), potassium, sodium.

Meat preparations (meat products, sausage products, tinned meat) are products made from the meat of various species and put through a special treatment, with various additives added that improve their organoleptic (taste, smell, appearance) and nutritional properties.

Meat preparations are divided, according to the technological process and the preservation used, into:

  • Sausages with a short shelf life (about 4 days) and a high tendency to change: sausages, Parizer, liver sausage, Prague ham.
  • Sausage products with an average shelf life (1-3 months): various kinds of salami,
  • Sausages with a long shelf life (up to 1 year): dried salami, Ghiudem and so on.

Besides sausages (mostly made from minced meat), the category of meat preparations also includes products obtained from various cuts of unminced meat (gypsy loin, pastrami, rib, ham – salted, dried, smoked, cooked, to improve their palatability, nutritional value and shelf life) as well as various meat pastes, meat juices and extracts, meat stock and so on.

The nutritional and energy value of the various kinds of meat products varies according to the range and the raw material used. Compared with meat, it is mostly higher. Digestibility is better in preparations with a shorter shelf life than in preparations with a long shelf life.

In the rational diet of a healthy person, all kinds of meat preparations can be used if they are kept under suitable conditions. In a therapeutic diet, only foods with a short shelf life are used, and only when very fresh.