With the support of the Erasmus+ program of the European Union LEARNING KIT MEAT PROCESSING CAVA PROJECT (Erasmus+ 2014 Call for proposal - Code 2014-1-IT01-KA202-002680) DIDACTIC UNIT (1-4) UNIT 1: meat definition UNIT 2: meat origin UNIT 3: structure of animal tissues and organs; connective tissue; offal UNIT 4: chemical composition of meat • Meat is food of animal origin, i.e. obtained by slaughter of livestock or by shooting or slaughtering wild game. • From culinary point of view: all muscle edible parts of animals. • The definition of meat may be wider or narrower, depending on what the term “meat” encompasses. In the wider sense, meat comprises all body tissues of slaughtered warm-blooded animals suitable for human consumption, including offal, adipose tissue, and blood. MEAT DEFINITION In a narrower sense, meat are muscles (muscle tissue) and bone base linked together by adipose and connective tissue. • Meat is easily perishable and therefore it can be kept in a state suitable for human consumption for only a short period of time. • In order to extend the meat keepability, different preserving and processing procedures are applied aiming at impeding, limiting or directing the microorganisms and tissue enzymes' activity and protecting the nutritional value of meat. • Moreover, the objective is to improve the organoleptic properties of meat and meat products. • The market offers fresh meat, refrigerated meat, frozen meat, MEAT DEFINITION semi-processed and processed meat, i.e. dried, smoked, sausages or salami, canned and cured meat cuts. • Slaughtering and primary carcass processing result in obtaining edible parts and secondary slaughter products. The edible parts comprise: muscle, adipose and connective tissue, including the internal organs (liver, heart, lungs, kidneys, tongue, glands etc.). • Secondary slaughter products are hides, bones, fat, hair, blood etc. and represent raw material for leather, chemical, pharmaceutical and other industries. • For human nutrition only muscle tissue of healthy animals is used. • Meat inspection (sanitary and veterinary inspection) includes ante-mortem inspection of animals, and post-mortem inspection of meat and organs (offal) after the processing in the abattoir. The inspection may determine the meat and the organs that are: fit for human consumption without limitations, conditionally fit for consumption, fit for processing or not fit for human consumption. • The inspected meat is marked with prescribed meat stamps MEAT DEFINITION that confirm the suitability for consumption. • Meat is obtained from carcasses of slaughtered animals. • The most significant livestock in the meat industry are cattle, sheep and pigs while buffaloes, goats and ungulates are less significant. • A second group of livestock from which meat is obtained is poultry (chicken, turkeys, ducks, geese, guinea fowls and domesticated pigeons) and rabbits. • Except livestock, meat production counts on game too: - mammals (hares, wild boars, deer, does) MEAT ORIGIN - birds (partridges, quails, wild geese, wild pigeons, turtle doves, pheasants...) • Animal organisms are made of different tissues each with a different chemical composition and structure. • Tissue consists of groups of cells with identical morphological and functional properties. • Except cells, tissues comprise two more elements: extracellular fluid and fibres. • Depending on the relation between these three elements in the tissue (their higher or lower share or complete absence) and the type of the cells, tissues are divided in simple and complex. STRUCTURE OF Simple tissues: epithelial tissue. Complex tissues: muscle tissue, connective tissue ANIMAL TISSUES AND (supportive tissue, adipose tissue, ORGANS blood), nervous tissue. • Epithelial tissue is a simple tissue formed by epithelial cells closely aligned on a thin barrier called basement membrane. Through the basement membrane, epithelial tissue is connected to other tissues and above all with the connective tissue. • Epithelial tissue has different function in the body. It covers the STRUCTURE OF whole body surface and coats all the cavities and organs, the ANIMAL TISSUES AND epithelial tissue most important function is protection. ORGANS Epithelial tissue • Muscle tissue is the engine of the whole body. It is formed by muscle cells that during the adaptation to their function have become elongated. • The muscle tissue, according to the shape of cells, location of the muscle and type of nerves that lead to the muscle, can be subdivided into: STRUCTURE OF a) Smooth muscle tissue, b) Skeletal muscle tissue and ANIMAL TISSUES AND c) Cardiac muscle. ORGANS Muscle tissue • Connective tissue is a complex tissue with the task to connect cells, tissues and organs while shaping them and providing the mechanical support. It also serves as protection and nutrition for organs. • Connective fibres give structure, thickness or flexibility to the connective tissue and the most important connective fibres STRUCTURE OF are: ANIMAL TISSUES AND • Collagen fibres, ORGANS • Elastic fibres and • Reticular fibres. Connective tissue • Tissues that absolve mechanical and supportive function are called supportive tissues, i.e. cartilage tissue and osseous tissue. STRUCTURE OF • The connective tissue, bones and cartilage, decrease the qualitative and nutritional value of meat. ANIMAL TISSUES AND ORGANS Supportive tissue: osseous and cartilage tissue • Adipose tissue is the main energy (in form of triglyceride) storage of the body. • The adipose tissue made of large spherical cells consisting of fat substances, either soft or stiff, has an especially high nutritional value. • For this reason the tallow is solid fat, lard is softer and fish fat is liquid. • The accumulated fat in adipose cells is the energy reserve STRUCTURE OF that the body uses upon request, protects the body from ANIMAL TISSUES AND loosing heat and from mechanical stress. ORGANS Adipose tissue • Offal refers to internal organs, which despite being edible parts are not considered meat in a narrow sense. • This category comprises: brain, heart, kidneys, liver, lungs, pancreas, spleen, tongue, udders, tripe, stomach, meaty parts of the head and legs, tails, snout, ears, diaphragm etc. • Despite being histologically (structurally) different from meat, their chemical composition and nutritional and energetic value is identical to meat. • The nutritional values are almost identical for offal and for meat. Internal organs - OFFAL • Edible organs are distinguished depending on the way they are processed: • Soft parts and organs: brain, heart, kidneys, liver, lungs, spleen, tongue, udders, diaphragm, oesophagus meat, thymus, fries. • Organs covered with mucous membrane: cattle rumen, swine stomach, poultry stomach, small intestine of calves, lambs and suckling pigs, large intestine of pigs, calves, cattle, sheep and lambs. • Osseous parts and carcass parts covered with hair: head Internal organs - OFFAL and limb parts, tails, swine skin, cattle snout. • Meat contains a whole range of nutritional substances in different shares, but the most important element are proteins. • Meat is an important nutrient as it contains a favourable ratio of the most nutritionally valuable elements: proteins, fats, minerals and vitamins. • The differences in chemical composition of meat from different animal species aren't significant and refer mostly to fat quantity. • Even though the differences are minimal, they depend on CHEMICAL many factors: animal species, breeding line, nutrition, sex and age of the animal, physiological state, external factors etc. COMPOSITION OF • Moreover, every single anatomic position on the carcass has a MEAT slightly different chemical composition depending on the function it has had during the lifetime. • The nutritional value of meat depends on proteins. • Total amount of proteins in meat is not sufficient for assessing its real nutritional value. CHEMICAL • Real nutritional value depends on the amino acid compound. COMPOSITION OF There are approximately 10 amino acids whose role has been proved as essential for human nutrition. Meat proteins contain MEAT: PROTEINS all these 10 irreplaceable amino acids and therefore meat is part of highly nutritious food group. • The quantity of proteins in meat is between 15 and 20%. • Meat contains 5 to 50% of fat. CHEMICAL • Fats have the highest relative energetic value. COMPOSITION OF MEAT: • The quantity of fat tissue reflects on the meat quality as it determines its basic properties as juiciness, smell and taste. FATS • Meat contains 50% to more than 70% of water. • Meat of different animal species and of different body parts of same animal contains different quantities of water. CHEMICAL • As the quantity of fats increases, the quantity of water is lower, and the energetic value of meat higher. COMPOSITION OF • The ratio of fats and water in meat has been proved to be MEAT: interrelated. WATER • Meat of young animals contains relatively more water in comparison to the meat of older animals (as a rule it is also lower in fats). • In animal tissues they are mostly present as glycogen (animal starch). Meat contains a small quantity of glycogen (0.05 to CHEMICAL 0.16%). COMPOSITION OF • The most of it is contained in liver and in muscles. Equine MEAT: meat contains more glycogen than other animal meat. Despite the rather small share of carbohydrates, they have a CARBOHYDRATES significant role in developing certain properties in the meat. (SACCHARIDES) After slaughtering, glycogen is transformed in lactic