Muscle Biology & Meat Science B. A. Reiling Know how. Know now. - PowerPoint PPT Presentation

Know how. Know now. Muscle Biology & Meat Science B. A. Reiling

Know how. Know now. What is Meat?  Animal tissue suitable for human consumption  Fresh Meats  no mechanical treatments or added ingredients • steaks, pork chops University of Nebraska – Lincoln

Know how. Know now. Conversion of Muscle into Meat Series of postmortem chemical reactions & physical changes  Loss of blood  loss of O 2  loss of ATP  ATP = energy required for muscle movement  With loss of ATP  Rigor mortis  Buildup of lactic acid  pH  from ~ 7.0 to 5.4 in 24 h University of Nebraska – Lincoln

Know how. Know now. With Anaerobic Metabolism, carbohydrates (glycogen) stored in muscle are broken Lactic ATP down for fuel, so muscle can Acid still contract post-mortem Lactic ATP CHO Acid for a limited time. CHO Lactic ATP  Also creates Acid CHO  “lactic acid” which causes the pH of muscle to drop from ~ 7.0 to 5.4 University of Nebraska – Lincoln

Know how. Know now. Conversion of Muscle into Meat  Muscles are designed for 1 of 2 purposes  1) locomotion  2) support  The anatomy, physiology, and function of each muscle affects meat palatability.  Locomotive muscles  more tough  Support muscles  more tender University of Nebraska – Lincoln

Know how. Know now. Palatability vs. Cost  Preferred retail cuts ...  Originate from the Rib & Loin (middle meats) • Muscles of support  TENDER; < connective tissue  Cost: $8 to $20 / lb  Less expensive cuts ...  Originate from the Chuck & Round (end meats) • Muscles of locomotion  TOUGH; > connective tissue - Exception = Flat Iron  Costs: $5 to $8 / lb University of Nebraska – Lincoln

Know how. Know now. Physical Composition of Meat  Muscle  major component  Muscle fibers composed of proteins  Connective tissue  surrounds each muscle fiber and bundle  Fat  Bone University of Nebraska – Lincoln

Sarcomere Smallest contractual unit of the muscle

Know how. Know now. Slide adapted The Sarcomere from Ty Schmidt (UNL Meat Science) Comprised of overlapping protein filaments  Thick filament = Myosin protein (80%)  Thin filament – Actin protein (20%) University of Nebraska – Lincoln

Know how. Know now. Sarcomere in state of rest Slide adapted from Ty Schmidt (UNL Meat Science) (uncontracted) University of Nebraska – Lincoln

Know how. Know now. Slide adapted Sarcomere in contracted state from Ty Schmidt (UNL Meat Science) University of Nebraska – Lincoln

Know how. Know now. Slide adapted Myosin Protein – Thick filament from Ty Schmidt (UNL Meat Science) ATP University of Nebraska – Lincoln

Know how. Know now. Slide adapted Actin Protein – Thin filament from Ty Schmidt (UNL Meat Science) Myosin Binding Site University of Nebraska – Lincoln

Know how. Know now. Slide adapted Sarcomere – Uncontracted from Ty Schmidt (UNL Meat Science) ATP Myosin Binding Site University of Nebraska – Lincoln

Know how. Know now. Slide adapted Sarcomere – Contracted from Ty Schmidt (UNL Meat Science) Myosin Binding Site University of Nebraska – Lincoln

Know how. Know now. Flank Steak Tenderization  Muscle fibers run in one direction  If cut “with the grain” • Intact, long muscle fibers  If cut “against the grain” • Many small pieces of fibers  Mechanical tenderization  Physical breakdown of muscle fiber cell walls University of Nebraska – Lincoln

Know how. Know now. Flank Steak Tenderization  Chemical tenderization  Meat is acidic (pH = 5.4) • Lactic acid production during rigor mortis  Soy Sauce or Baking Soda is basic  Chemical reaction  breakdown of proteins  Enzymatic Breakdown – Papain  Breaks down the myosin protein University of Nebraska – Lincoln

Know how. Know now. Effect of Cooking on Tenderness  For a TOUGH piece of meat, what cookery method should result in the most tender, cooked product? Why?  Hey, this could be an experiment! University of Nebraska – Lincoln

Know how. Know now. Effect of Cooking on Tenderness  Dry Heat -- Broiling & Grilling  High temp, short time  tender cuts  Sear outside to “lock in” juice  Fiber & connective tissue breakdown • not an issue; originated from muscles of support  Moist Heat -- The “crock pot”  Low temp, long time  tough cuts • To an internal temp of ~180 o F  Heat & moisture break down connective tissue University of Nebraska – Lincoln

Know how. Know now. Key Points: Muscle Biology  Muscle requires energy (ATP) to contract  During rigor mortis, muscle pH  to 5.4  Muscle = bundles of muscle fibers  Sarcomere is smallest contractile unit  Muscles of support vs. locomotion University of Nebraska – Lincoln

Know how. Know now. Extension is a Division of the Institute of Agriculture and Natural Resources at the University of Nebraska – Lincoln cooperating with the Counties and the United States Department of Agriculture. The Youth Development program abides with the nondiscrimination policies of the University of Nebraska – Lincoln and the United States Department of Agriculture. University of Nebraska – Lincoln