moisture
The water content in the muscle of livestock and poultry meat is about 75%, which exists in the form of bound water, stagnant water and free water. The bound water accounts for about 5% of the total water content of muscle, which is closely combined with the surface of protein molecule and the electrostatic attraction of water molecules by means of polar groups to form a water molecule layer; The immobile water accounts for about 80% of the total water content of muscle, and exists among myofibrils, myofibrils and muscle membranes in the state of immobile water. Free water accounts for about 15% of total muscle water, exists in extracellular space and can flow freely.
protein
The protein content of livestock and poultry meat is 10%-20%, which varies with animal species, age, fatness and location. In livestock meat, the average protein content of pork is about 13.2%; Beef is as high as 20%; Mutton is between pork and beef; The protein content of rabbit meat, horse meat, venison meat and camel meat is also about 20%. Dog meat is about 17%. In poultry meat, the protein content of chicken is relatively high, about 20%; Duck meat is about16%; Goose meat is about18%; The protein content of quail is as high as 20%.
The protein content of meat in different parts of animals is quite different because of the degree of fatness and thinness. For example, the protein content of pork tenderloin is about 2 1%, the rear buttock tip is about 15%, the rib meat is about 10%, and the breast is only 8%; The protein content of beef tenderloin is about 22%, hind leg meat is about 20%, rib meat is about 18%, and front leg meat is about16%. The protein content of sheep's foreleg meat is about 20%, hind leg meat is about 18%, and the meat of spine and chest is about17%. Protein content of chicken breast is about 20%, and that of chicken wings is about 17%.
Generally speaking, heart, liver, kidney and other internal organs have higher protein content and less fat content. The content of protein in different viscera is also different. In different viscera of domestic animals, the protein content in liver is high, which is 18%-20%, and the protein content in heart and kidney is14%-17%. Protein 13%- 17% was found in the liver and heart of poultry.
Protein of livestock and poultry meat is completely protein, which contains all kinds of essential amino acids, and the proportion of essential amino acids is close to the needs of human body, so it is easy to be fully utilized by human body and has high nutritional value, so it belongs to high-quality protein.
The skin and fascia of livestock and poultry are mainly composed of connective tissue. The protein content of connective tissue is 35%-40%, and most of them are collagen and elastin. For example, pigskin contains 28%-30% protein, of which 85% is collagen. Because collagen and elastin lack essential amino acids such as tryptophan and methionine, they are incomplete protein, so they need to be combined with other foods to supplement essential amino acids.
Bone is a kind of hard connective tissue, in which protein content is about 20%, and collagen accounts for a large proportion, which is an incomplete protein. Bone can be processed into bone paste and added to meat products to make full use of protein.
The contents of protein in the blood of livestock and poultry are as follows: pig blood 12%, cow blood 13%, sheep blood, chicken blood and duck blood. Animal blood plasma protein contains 8 kinds of essential amino acids and histidine, which has high nutritional value. Its lysine and tryptophan contents are higher than those of flour, and it can be added to various foods and meals as a protein fortifier. Blood cells can be used in sausage production, and their amino acid composition is similar to collagen. When hydrolyzed by collagenase, gram can get the same peptides as collagen hydrolysate.
fat
The fat content of livestock and poultry meat varies greatly due to the variety, age, degree of fatness and location of animals, ranging from 2% to over 89%. Among livestock meat, pork has the highest fat content, followed by mutton and beef. For example, the fat content of pig lean meat is 6.2%, sheep lean meat is 3.9%, and beef lean meat is only 2.3%. The fat content of rabbit meat is also low, which is 2.2%. In poultry meat, the fat content of turkey and quail is low, below 3%; The fat content of chicken and pigeon is similar, between 14%- 17%; The fat content of ducks and geese is about 20% higher.
The fat composition of livestock meat is mainly saturated fatty acids, mainly composed of stearic acid, palmitic acid and oleic acid, with a high melting point. Poultry meat fat contains more linoleic acid, has a low melting point and is easy to digest and absorb. Cholesterol content in lean meat is low, about 70mg per100g, fat meat is about 90% higher than lean meat, higher in viscera, generally about 3-5 times that of lean meat, and the cholesterol content in brain is the highest, which can reach more than 2000mg per100g.
The content and composition of essential fatty acids is an important aspect to measure the nutritional value of food oils. Animal fat contains significantly less essential fatty acids than vegetable fat, so its nutritional value is lower than vegetable fat. Among animal fats, the content of essential fatty acids in poultry fat is higher than that in livestock fat; The essential fatty acid content of pig fat is higher than that of ruminants such as cattle and sheep. Generally speaking, the nutritional value of poultry fat is higher than that of livestock fat.
carbohydrate
The carbohydrate content of livestock and poultry meat is 1%-3%, with an average of 1.5%, which mainly exists in muscle and liver in the form of glycogen. Animals are overtired before slaughter, and the glycogen content decreases, and the storage time after slaughter is too long. Also, due to the action of enzymes, the glycogen content decreases, the lactic acid correspondingly increases, and the PH decreases.
mineral
The mineral content of livestock and poultry meat is 0.8%- 1.2%, and the content in lean meat is higher than that in fat meat and viscera is higher than that in lean meat. The content of iron is about 5mg/ 100g, and pig liver is the most abundant. Iron in livestock and poultry meat mainly exists in the form of heme, which has a high digestion and absorption rate. The viscera is also rich in zinc and selenium. The selenium content of bovine kidney and pig kidney is dozens of times that of other general foods. In addition, there are more phosphorus, sulfur, potassium, sodium and copper in livestock and poultry meat. Although the content of calcium is not high, its absorption and utilization rate is high.
The liver of poultry is rich in many minerals, and the average level is higher than that of poultry meat. The content of iron in liver and blood is very rich, as high as 10-30mg/ 100g, which can be regarded as the best dietary source of iron. Birds' hearts and gizzards are also foods rich in minerals.
vitamin
Livestock and poultry meat can provide a variety of vitamins, mainly B vitamins and vitamin A. The content of viscera is more than that of muscle, and the liver is the most abundant, especially vitamin A and vitamin B2. The content of vitamin A is the highest in bovine liver and sheep liver, and the content of vitamin B2 is the richest in pig liver. There is also more vitamin E in poultry meat.