LPT 601: FRESH MEAT TECHNOLOGY - PowerPoint Presentation

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LPT 601: FRESH MEAT TECHNOLOGY UNIT I: Structure and chemistry of animal tissues

Dr. R. K. JaiswalAsstt. Prof.-cum-Jr. ScientistDept. of Livestock Products TechnologyBihar Veterinary CollegeBihar Animal Sciences UniversityPatna-800014 (Bihar)

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Meat

Animal tissues which are suitable for use as food More precisely edible postmortem component originating from live animals

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Meat terms

Meat ScienceThe basic study of the unique characteristics of muscle and other animal tissues that are used as meat, includes all facets of the meat industry, beginning with animal production and ending with final preparation for consumption. Meat Technology

Deals with the handling, processing, packaging, preservation and marketing of meat, meat products and byproducts at industrial scale.

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Muscle tissueNervous tissuesEpithelial tissuesConnective tissuesAdipose Tissues

Muscle and Associated TissueTypes of Tissues

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Types of Muscular TissueSkeletal MuscleVoluntary and striatedSmooth Muscle

Involuntary and smoothCardiac MuscleInvoluntary and striated

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Skeletal Muscles

There are more than 600 muscles in animal bodyVary widely in shape, size and actions.In general Skeletal muscle constitute 35-65% of meat Muscle fiber constitute 75-92% of total muscle volume. Remaining are connective tissues, blood vessels, nerve fibers and ECF

Muscle bundle

Muscle

Muscle

Muscle fiber

Myofibril

Myofilaments

Epimysium

Perimysium

Endomysium &

Sarcolemma

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Structure of Cell

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Sarcolemma

Membrane surrounding the Muscle fiberMade up of protein and lipid materialElastic in natureInvaginations from Sarcolemma forming a tubular network Transverse Tubules/ T system/ T TubulesSmall mound on the surface of muscle fiber (sarcolemma) where motor nerve fiber terminate – Motor End Plate

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Sarcoplasm

Cytoplasm of Muscle cellIn addition to 75-80% water contains lipid droplets, glycogen granules, ribosomes, numerous protein, NPN compounds and inorganic constituentsNucleiMultinucleatedAt tendinous attachment more concentrated and irregularly distributed.High in number at motor end plate

Peripheral in location in mammals whereas in fish central.

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Myofibrils

Usually 1-2 μm in diam.Parallel to long axisFibers with diam. of 50 μm can accommodate 1000-2000 myofibrilsContractile unit is sarcomere (between two adjacent Z line)Light and dark band I Band (Isotropic/less dense) singly refractive, whereas A Band (Anisotropic/much dense) doubly refractive – I band bisection by thin dense line –Z line

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Thick filaments of vertebrates 14-16 nm in diam. and 1.5

μm long (Myosin predominant/A band)Thin filaments of vertebrates 6-8 nm in diam. and 1.0 μm long on either side of Z disc (Actin predominant/ I band)Orderly arrangements of Thick and Thin filamentThick and thin overlapping in certain region accounts for striations In cross section of A band region Six thin filaments surround each thick filamentEach Actin filaments connect with 4 oblique Z filaments (Z line)

Myofilaments

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Sarcoplasmic reticulum

System of Tubules and cisternae/Intracellular membrane structure acting as Flattered reservoirs of Ca2+ and corresponds to ER of other cells Thin tubules of SR oriented in direction of myofibril- Longitudinal tubules and in H zone it forms a perforated sheet called as fenestrated collar.At the junction of A and I band the longitudinal tubules join with lagers transversely oriented tubules called terminal cisternae.The T tubules also runs transversely across the sarcomere at A-I junctionConnecting elements exist between terminal cisternae and T tubules.SR and T tubules are separate, SR constitute 13% of total muscle fiber volume where as T tubules approx 0.3%.

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Mitochondria

Powerhouse of cellGreat variation in mitochondrial size and their number in muscle fibersAbundant at periphery near the poles of nuclei and motor end platesAdditional at A-I band junction, Z disc and I bands

Lysosomes

Cathepsins a group of proteolytic enz.

Golgi Complex

Near the nuclei

Flattened vesicles, function as concentrating and packaging apparatus.

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Sarcomere length, Dimension of I band and appearance of H Zone, Pseudo H zone and M line change with contraction state.

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Innervated by the Autonomic Nervous System Found primarily in the walls of hollow organs & tubes In most of the case spindle-shaped cells typically arranged in sheets Single nucleus centrally locatedCells do not have t-tubules & have very little sarcoplasmic reticulum

No Z line or M line and striationActin and Myosin in same proportionOccurs single or in bundle and surrounded by network of reticular fiberSmooth Muscles

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Two types of smooth muscle: 1. Visceral or Unitary smooth muscleFound in the walls of hollow organs (e.g., small blood vessels, digestive tract, urinary system, & reproductive system) Multiple fibers contract as a unit (because impulses travel easily across gap junctions from cell to cell) &, in some cases, are self-excitable (generate spontaneous action potentials & contractions)

2. Multiunit smooth muscle   Consists of motor units that are activated by nervous stimulation Found in the walls of large blood vessels, in eye (adusting the shape of the lens to permit accommodation & the size of the pupil) Contd..

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Cardiac MuscleMyocardium, the contractile layer of the heart, contains the bulk of the cardiac muscle Single centrally placed nucleus, fibers branched and shorterSarcoplasm with numerous glycogen granules Mitochondria especially large and numerous, extensive blood circulation.

Aggregates of myofilaments form fibrils of extremely variable size T Tubules at Z disc, SR less developed and terminal cisternae absent.Intercaleted disc- transecting the fiber, occurs at regular interval across I bands

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Cardiac Muscle

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