Lecture 5- Meat Flashcards
Define meat
Animal tissue used for food
What is the leading meat in the world? What did it used to be?
Chicken now, used to be pork
What are the 3 primary muscle types and their common names?
- Smooth- wall of digestive tract + capillaries
- Involuntary striated (cardiac)
- Voluntary striated (skeletal) - alternating white and dark bands
5 parts to muscle structure
- Myofibers
- Sarcolemma- excitable cell membrane
- Nuclei
- Myofibrils- contractile filaments in myofibers
- Sarcoplasm- liquid
What is the difference between sarcolemma and endomysium?
Sarcolemma is a cell membrane and endomysium is a connective tissue
Voluntary striated muscle has multiple nuclei while
Involuntary striated has a single nuclei
3 parts to connective tissue network
Endomysium- thin, surrounds individual cells
Perimysium- buddles several muscle cells
Epimysium- surrounds entire muscle cell
2 types of myofibrils
Actin (light) and myosin (dark)
Muscle sliding is regulated by ___ which is held in the ______ _______.
Ca++, sarcoplasmic veticulum
Describe a sarcomere
It’s the smallest contractile unit and consists of actin and myosin between z-lines.
Actin and Myosin filament length _____ changes.
NEVER
2 roles of ATP
- Relaxation- separates actin and myosin
- Contraction- provides energy
3 methods of anaerobic metabolism
ATP = ADP + energy
Phosphocreatine = Creatine + energy
Glycogen (glucose) = lactic acid + energy
What metabolism mostly happens when an animal dies and what is the largest by product?
Anaerobic produces lactic acid
What are 3 methods of aerobic metabolism?
Glycogen + 02 = H20 + CO2 +energy
Lactic Acid + 02 = H20 + CO2 +energy
Fatty Acid + 02 = H20 + CO2 +energy
Define rigor mortis
Stiffening of the carcass by intense shortening of the muscle fibers
Define rigor onset
Muscle relaxed; most tender
Define rigor completion
Maximum contraction and maximum toughness
Define resolution of rigor
Autolysis: enzymes (cathepsins and calpains) breakdown protein and meat becomes more tender
(Muscle is NOT relaxing)
What pH is needed to begin resolution of rigor mortis? Why does the pH drop?
PH 5.6 because of lactic acid build up
Where does water in bottom of meat packages come from?
Water binding capacity drops as the pH drops
Why is meat aged?
To improve flavor and tenderness
What is the relationship between time and temperature when aging meat?
Less time at higher temps. (Watch out for microbial growth)
2 other methods if aging meat
Add proteolytic enzymes (ex. Papain from papaya)
Wet aging - meat sits in its own fluid
What % of meat is water?
75%
What % of meat is protein?
19%
What % of meat is lipids?
4%
What % of meat is carbohydrates?
1%
What % of meat is minerals?
1%
What % of pigs (monogastrics) fatty acids are unsaturated?
54%- more unsaturated than ruminants
What % of cow (ruminants) fatty acids are unsaturated?
46%- less unsaturated than monogastrics, sheep have even less
What % of poultry fatty acids are unsaturated?
66% (like eggs)
What is unique about monogastric meat contents?
The contents can be changed through the animals diet unlike w/ ruminants.
What is the most common fatty acid in all meats?
Oleic
Protein nutritional value is …
Similar across all meats
Rank milk, meat and eggs by protein nutritional value.
- Eggs
- Milk
- Meat
List specific proteins
Actomyosin; myoglobin (transport O2 and CO2); troponin; tropomyosin; enzymes; collagen; nucleoproteins
What are inedible proteins in meat?
Elastic keratin and collagen (only edible is cooked over long time like roasts)
What carbohydrate is in meat?
Glycogen (mostly gone after rigor mortis)
What vitamins does meat have?
B12, Niacin, Riboflavin, B6, (Beef lots of B12; Pork lots of thiamine)
What three minerals are in bone matrix of meat?
Mg, Ca, P
What minerals can you find in meat?
Fe, Zn, K, S, Na, Cl
Meat is ____ nutrient dense.
Very/pretty
What 2 factors affect meat color?
- pH of muscle (if not enough lactic acid meat gets really dark)
- active muscle = more myoglobin = darker
Where does meat aroma and flavor come from?
- Subtle combinations (organoleptic)
- Volatile compounds - released by heating
- Water soluble and fat soluble compounds - most influence
Define juiciness
Wetness produces by the release of meat fluids (2nd to tenderness in palatability)
What 2 factors influence juiciness?
- Cooking procedure
- more marbling = more juice (intramuscular fat)
Define tenderness
Measurement of hoe easily meat can be cut or chewed; measured resistance to shear force; 1st palatability factor
5 factors that influence tenderness
- More connective tissue= less tender
- Cooking method
- Freezing (maybe makes more tender)
- Coarseness (small fibers= more tender)
- Older animal = less tender
Describe how cooking method affects meat tenderness.
Myofibrils become tougher w/ heat (ex. High quality steak is cooked short time)
Connective tissues become tender w/ heat (ex. Roasts in a crockpot)
5 pre-slaughter factors that effect meat quality
Hereditary - tenderness is highly heritable
Physiological age - older is tougher
Physiological hormones - castrate to block testosterone
Feeding/ management
Stress at slaughter - less stress= more glycogen stores= better rigor resolution
4 post-slaughter factors that effect meat quality
Chilling
Aging
Freezing - inhibits microbial growth
Electrical stimulation (shock) - mostly for color
Why is poultry not aged?
The more unsaturated fat could cause oxidized flavor.
Dressing percentage is …
Sheep=
Cow=
Pig=
How much meat from a carcass
Sheep= 50%
Cow= 60%
Pig= 72% (less stomach weight too)
Meat inspection is completed by the
Food Safety and Inspection Service (FSIS) under the Department of Agriculture
= paid for by taxes
2 meat inspection acts
Meat Inspection Act of 1906
Wholesome Meat Act of 1967
Purpose of meat inspection
To ensure meat is wholesome and suitable for consumption (every animal gets inspected)
What three things are evaluated?
Free of disease- especially organs and LUNGS!
Clean, sanitary facility
Proper packaging and labeling (more serious recent years b/c fish fraud)
Meat grading is based on …
Aspects of meat desired by consumers; guidelines made by USDA; paid by meat packers
What are private grades?
When meat packers make their own grading system.
USDA grades for beef
Quality- estimate of palatability = flavor and tenderness based on age and marbling
Yield - quantity of boneless, closely trimmed retail cuts, fat, muscle, and weight = 1,2,3,4,5
What are the 4 quality grades of beef?
Prime - most marbling - at steakhouse
Choice - most common
Select
Standard - least marbling
Pork grades
Yield and quality in one grade
1,2,3,4
Poultry grades
A (whole birds), B + C (fast food)
4 forms of meat marketing
- Carcasses = beef, sheep, swine
- Wholesale/retail - boxed products (primal cuts)
- Kosher meats, Halal meats -religious guidlines
- Variety meats (organ- wrong term)
What are common pathogens in meat?
Salmonella - most food borne illnesses
Campylobactor
E. Coli
Listeria - can live at cold temps.
Why are ground meats need to be cooked at much higher temperatures? What temp is that?
Bacteria from the outside of meat has been mixed into the middle - 160F
Define Hazard Analysis Critical Control Points (HACCP)
Systematic approach to food safety that identifies and eliminates hazards at various points in food production and processing
Pork production in million metric tons in 2023?
122
Chicken production in million metric tons in 2023?
140
Beef production in million metric tons in 2023?
72
Sheep production in million metric tons in 2023?
17
