Transcript Meat Science

MEAT SCIENCE
Animal
Agriculture
OBJECTIVES IN BASIC SCIENCE
 Describe physiological processes that take place in an
animal’s body at death.
 Describe the process of ossification.
 List the dif ferent types of tissue that make up muscle.
 Explain the factors that af fect the sensation of taste.
 Explain why meat is so highly perishable.
 Discuss the types of microbes that cause spoilage.
 List the factors that favor the growth of microbes.
 Discuss the scientific principles behind the preservation of
meats.
OBJECTIVES IN AGRICULTURAL SCIENCE
 Explain the steps in the slaughter of meat animals.
 Distinguish between quality grading and yield grading of
carcasses.
 List the wholesale cuts of beef, pork and lamb.
 Discuss the factors that af fect the palatability of meats.
 Discuss the various methods used to preserve meats.
KEY TERMS ~ WWW.M-W.COM
Wholesale
Retail
Immobilize (body or part)
Kosher
Exsanguination
Chine
Shroud
Rigor Mortis
Primal
ENTERING THE SLAUGHTERHOUSE
 Animals leaving the farm to the slaughterhouse are
kept as calm as possible, to prevent bruising and to
keep the muscles relaxed.
 First step at the slaughterhouse is immobilization*.
 Regulations for the immobilization process are set by
the Federal Humane Slaughter Act, passed in 1958.
FEDERAL HUMANE SLAUGHTER ACT
 No method of slaughtering or handling in connection with
slaughtering shall be deemed to comply with the public policy of the
United States unless it is humane. Either of the following two
methods of slaughtering and handling are hereby found to be
humane:
 (a) in the case of cattle, calves, horses, mules, sheep, swine, and
other livestock, all animals are rendered insensible to pain by a
single blow or gunshot or an electrical, chemical or other means
that is rapid and effective, before being shackled, hoisted, thrown,
cast, or cut; or
 (b) by slaughtering in accordance with the ritual requirements of
the Jewish faith or any other religious faith that prescribes a
method of slaughter whereby the animal suffers loss of
consciousness by anemia of the brain caused by the simultaneous
and instantaneous severance of the carotid ar teries with a sharp
instrument and handling in connection with such slaughtering.
IMMOBILIZATION
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Immobilization may be done in several ways:
CO2 Chamber – animals go to sleep due to lack of oxygen
Electrical Shock – electrical shock to animal’s head & heart
Bolt – head shot delivered via cartridge or compressed air
Electric water bath – heads are submerged in an electrified bath
 Kosher* livestock are exempt from Humane Slaughter Act.
 Any food produced, killed or prepared according to Jewish dietary
laws. These animals are killed via sharp knife to neck.
 Immobilized animals are then hung
on the rail for exsanguination, skinning,
cut-up and inspection.
THE RAIL
 Animals must be quickly bled out to keep from regaining
consciousness and to prevent hemorrhaging (escape of blood)
 Exsanguination* – blood pressure drops, causing the heart to speed
up, which pumps 50% of the blood out and most rest to the organs
 The hide and internal organs or entrails are removed.
 Liver, Pancreas, intestines, heart, brain, and kidneys are kept.
 Federal USDA inspectors inspect all of the internal organs and
every carcass to detect any health concern.
 Carcasses are prepared for the cooler – beef are sawn down
the chine*into halves known as “sides of beef.”
 Lamb carcasses are sent to the cooler whole.
 Hog carcasses are sent to the cooler as “half hogs.”
 Skinned carcasses are wrapped in salt -water shrouds*
CARCASSES ON THE RAIL
THE COOLER
 Quickly reduce carcass temperature, to minimize protein
degradation and growth of microorganisms.
 Rigor Mortis* onsets between 30min – 12 hours and partially
relaxes as enzymes break down muscle tissue.
 Carcasses require between 18 and 30+ hours to cool. Higher quality beef may undergo week -long period of aging, which
allows further tissue breakdown, tenderizing the meat.
 An alternative to the aging period
is electrical stimulation.
 600 volts speeds up the natural death
process, tenderizes the meat, and
improves color and texture.
USDA GRADING
 After the carcasses cool, they are graded to USDA standards.
 Federal Meat Grading was established in 1925 by the Agricultural
Marketing Service (AMS) and the USDA.
 Meat grades certify the class, quality and condition of the
product examined to conform to uniform standards.
 Two types of USDA Grading Scales:
 Quality Grades are a prediction of the eating quality ( palatablity) of
properly prepared meats.
 Yield Grades indicate expected yield of edible meat from a carcass –
how many cuts of meat will come from that carcass.
QUALIT Y GRADES
USDA QUALITY GRADE
QUALIT Y GRADES
 Grades are determined by
the age of the animal at
slaughter and the amount
of fat intermingled with the
muscle fibers.
 Age is determined by the
maturity of the cartilage
and bones in the carcass.
As animals age, cartilage
hardens into bone.
 Graders inspect the rib
cage and vertebrae for the
degree of bone and
cartilage hardening, called
ossification.
QUALIT Y GRADES
USDA QUALITY GRADE
CHARACTERISTICS OF THAT GRADE
Prime
Highest quality & marbling. Approx. 3% of supply.
Choice
Slightly less marbling than Prime. Over 50% of supply.
Select
Lowest retail grade. Acceptable, but lean and dry.
Standard
Lower quality, yet economical. Lacks marbling.
Commercial
Low quality. Lacks tenderness. From older animals.
Utility
Only used in processed & canned meat products.
Cutter
Only used in processed & canned meat products.
Canner
Only used in processed & canned meat products.
QUALIT Y GRADES
 The amount of marbling
is determined by
examining the longissmus
dorsi (rib eye), between
12 th & 13 th rib.
 The more white specks of
fat that are visible, the
higher the grade.
 Prime beef has the
highest degree of fat in
the muscle. Fat gives
meat its flavor and
juiciness.
USDA QUALIT Y GRADES
MARBLING RATINGS
Moderately Abundant
Slightly Abundant
Moderate
Modest
Small
Slight
YIELD GRADES
 Yield grades are an estimate of the percentage of boneless,
closely trimmed retail cuts that come from the primal* cuts
(round, loin, rib and chuck).
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USDA Yield Grades for beef are…
1: More than 52.3% lean primal cuts
2: 50.0 - 52.3% lean primal cuts
3: 47.7 - 50.0% lean primal cuts
4: 45.5 - 47.7% lean primal cuts
5: less than 45.5% lean primal cuts
 Yield grades start with the size of the rib eye and back fat.
YIELD GRADES
YIELD GRADE FACTORS
Chilled carcass weight
Amount of internal fat
(kidney, pelvic, heart)
Size of rib eye area
Amount of back fat
WHAT’S A GRADE LOOK LIKE ALIVE?
U.S. BEEF GRADING
http://www.youtube.com/watch?v=tEHwm1gIj-w&t=6m38s
THE WHOLESALE CUTS
 After leaving the cooler, beef carcasses are cut into pieces
that are sold to retailers – these pieces are the primal cuts.
 Beef – chuck, loin, rib, and round
 Pork – shoulder, loin, sides, and ham
 Lamb – shoulder, rib, loin, and leg
 Poultry – breast, wing, leg, thigh
 Primal cuts “cut away” about 30% of excess fat and bone,
which saves on shipping costs.
 Primal cuts also give retailers an advantage of ordering only
what they need, instead of getting everything regardless.
BEEF PRIMAL CUTS
PORK PRIMAL CUTS
LAMB PRIMAL CUTS
POULTRY PRIMAL CUTS
WHOLESALE TO RETAIL
 Retail cuts are those that the consumer buys at the store.
They are sized into portions that require no extra cutting or
trimming and are easy to cook.
 The most expensive cuts of meat come from the loin.
 This is the most tender of the muscle groups.
 Products include chops and steaks, such as the T-Bone.
 Portions that have been cut away during trimming, or poor
retail cuts of meat are often made into sausage or ground.
FACTORS AFFECTING PALATABILIT Y
 Palatability refers to how a food appeals to the palate
(taste).
 Meat palatability depends on qualities such as…
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Appearance
Tenderness
Juiciness
Flavor
Aroma
AS WELL AS THE WAY IT WAS COOKED!
 But, since consumers buy most retail meat uncooked,
most concern is put into the first qualities*.
 Only some stores help consumers with cooking techniques…
PALATABILIT Y & APPEARANCE
 Appearance is the first factor that influences the choice of the
consumer – before even reading the price!
 Beef, pork and lamb all vary in the shades of red color.
 Darker meat is associated with lack of freshness OR meat
from an older animal – both of which af fect palatability!
 Bright red meat gives the appearance of being fresh &
wholesome.
PALATABILIT Y & APPEARANCE
 The amount and color of a cut of meat’s fat is also taken into
consideration with appearance.
 Fat that is yellow in color is less appealing than creamy white color.
 Yellow fat is caused by animals that cannot convert carotene
(pigment found in feeds, fats and eggs) to Vitamin A .
 Grass fed beef are common to have
yellow fat, due to being fed an excess
of carotene.
 Consumers also realize that a cut
of meat with a lot of fat and bone
has less edible meat or more waste .
PALATABILIT Y & TENDERNESS
 Tenderness is a sensation that has several components, is
very dif ficult to measure and has been studied considerably!
 Terms to describe tenderness during chewing include…
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Resistance to Tooth Pressure
Softness to Tongue & Cheek
Ease of Fragmentation
Mealiness
Adhesion or Stickiness
Residue After Chewing
 On a Meat Science level, it is dif ficult to describe eating
tender vs. tough meat.
 It is also difficult to use mechanical devices to measure this too!
PALATABILIT Y & TENDERNESS
 Connective Tissue – tendons, collagen,
cartilage and bone
 Collagen – abundant protein in active areas
 State of Muscle Fibers – how contracted?
 Adipose* - little influence on tenderness,
but important to palatabilty
 In fact, research shows that marbling may act
as a lubricant during mastication* - aiding in
the digestive process!
 Animal age can be determined by
cooking…
 As the animal gets older, the collagen become
less soluble and resistant to cooking. This is
seen as the gelatin material in the pan after
cooking a pot roast.
PALATABILIT Y & TENDERNESS
 Elastin* is found
throughout the
ligaments, arteries, and
structures of an animal.
 These fibers can easily
stretch and return to
their natural state when
released.
 Cooking has no affect on
this, so cuts of meat high
in elastin are tougher to
chew.
PALATABILIT Y & JUICINESS
 Avoid both ends of the juiciness spectrum!
 Meats that appear dry, firm and dark (DFD) indicate a lack of freshness
or meat from an older animal.
 Meats that are extremely moist indicate a pale, soft and exudative
(PSE) condition associated with some meats.
 PSE conditions are caused by abnormal metabolism after slaughter, low pH
levels within meat and stress prior to slaughter.
 A meat’s juiciness is important in the perception of palatability
to consumers.
 Since the juice is made of water and
melted fats, it stimulates saliva production,
contains flavoring components and assists
in digestion – lubricating, softening and
fragmenting the meat!
PALATABILIT Y & FLAVOR
 A meat’s flavor often changes after extended storage periods.
 The chemical breakdown of nucleotides (flavor components)
impart a desired aged flavor.
 Oxidation* of fatty acids, known as oxidative rancidity result
in a rancid flavor and a unpleasant odor!
 This is another reason to keep your eyes on the “use by date!”
PALATABILIT Y & AROMA
 Aroma is detected from numerous gaseous aspects of meat
that stimulates the nerve endings in the linings of our nasal
passages.
 The total sensation is a combination of taste AND smell.
 The meaty flavor that we taste, combined with the aroma of a
cooked steak stimulate the flow of gastric juices and saliva,
both which help us digest and increase the apparent juiciness
of the meat!