Slaughtering
and Meat Processing
ALONA T. BADUA, DVSM, MVSt.
Professor
Department of Animal Science, College of Agriculture
Central Luzon State University
A. Composition and Nutritive Value of Meat
1. Importance of meat in the diet
Meat is very important in the diet for it is a source of:
a. Protein
 Vital nutrient in the growth process and for building and maintaining body tissues
 Meat contains high quality (high biological value) and quantity protein
b. Fat
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Important component of balanced diet
It adds flavor, appetite, appeal and satiety value of foods
It is a concentrated source of calories
Provide essential fatty acids and aid in the absorption of fat-soluble vitamins
It also contains a certain amount of non-beneficial cholesterol
c. Minerals
 Meat is a good source of iron, zinc, potassium and phosphorus but is low in
calcium
 The cooking and processing of meat do not appreciably affect the quantity or
availability of the mineral elements as long as mineral salts are added.
d. Vitamins
 Meat is an excellent source of B-complex vitamins (thiamin, riboflavin, niacin,
pyridoxine and cyanocobalamin) and is poor in the fat -soluble groups and
vitamin C.
 Muscle is a poor source of vitamins A, C, D, E and K, the small quantities present
in the fresh meat are destroyed during cooking and processing.
 Liver is the greatest single food source of vitamins A, D and K
2. Categories of Meat
Meat - defined as animal tissues, which are suitable for use as food. All processed or
manufactured products, which might be prepared from these tissues are included in
this definition
Categories of meat
a. red meat
 largest category in terms of volume and consumption
 example: beef, pork, lamb or mutton and veal
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b. poultry meat
 derived from flesh of domestic birds
 example: chicken, turkey, geese, duck and guinea fowl
b. sea foods
 flesh of aquatic organisms of which the bulk are fish
 example: flesh of clams, lobsters, oysters, crabs etc.
c. game meat
 flesh of non-domesticated animals
 example: venision, starmeat
3. Classification of meat based on species
a. hog – pork
b. cattle (< 1 yr ) – veal
c. cattle (> 1 yr ) – beef
d. carabao – carabeef
e. chicken, duck, quail, goose, pigeon – poultry meat
f. horse – horse meat
g. sheep (< 1 yr ) – lamb
h. sheep (> 1 yr ) – mutton
i. goat – chevon
j. rabbit – lapan
k. deer – venison
l. rats – starmeat
4. Composition of meat
a. Physical composition
This refers to the components of meat that can be physically separated. This includes
the muscle, fibrous connective tissues, fat, bone and skeletal tissues.
1) Muscle and fibrous connective tissues
The skeletal tissue is attached indirectly to the bone and facilitates movement and/or
gives support to the body. From an economic standpoint, skeletal muscle is the most
important and it is the major component of the carcass.
Muscles that are used for locomotion and power (e.g. in the legs and shoulders) have
more connective tissue and yield less tender meat. The muscles of support (e.g. those in the
back, rib and loin) move less, are not as important for locomotion or power and are much
tender. Other muscles, such as those in the portion of the shoulder nearest the rib, in the
rump and in the upper portion of the hind leg, provide moderately tender meat.
2) Adipose tissue
Site of fat deposition (sites of higher priority to lesser priority)
a. kidney, heart and in the pelvic area
b. external or subcutaneous (finish)
c. between muscles (intermuscular or seam fat)
d. within the muscles (as intramuscular fat or marbling)
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Intramuscular fat (marbling) is deposited, if and only if, needs of the adipose tissue sites of
higher priority for fat deposition have been satisfied (e.g. around the organs, under the skin
and between the muscles).
3) Bone and skeletal tissue
Skeletal tissue is a type of connective tissue that consists of bones, tendons, ligaments
and cartilage
b. Chemical composition
Chemical composition of meat is determined by chemical analysis. It is important
because it largely determines the nutritive value of meat. The most abundant chemical
constituent of meat is water. In a broad sense the composition of meat can be approximated to
75 percent of water, 19 per cent protein, 3.5 per cent protein and 2.5 per cent of fat.
1) Water
 Meat contains 45-75% moisture
 The younger and leaner the animal, the higher the moisture content
 The fatter the animal, the lower the water content of its carcass or cuts
 Texture, color and flavor of the muscle are affected by the amount of water in muscle
tissue
2) Protein
 Meat proteins are grouped in three general classification:
a) myofibrillar proteins (salt soluble)
 These are also called contractile protein because they play a role in muscle
contraction and locomotion. This function in the development of rigor mortis.This is
composed of actin and myosin and the combination form of actomyosin.
 These proteins are also called salt soluble proteins because they are commonly
extracted with potassium chloride and important in sausage making.
b) stromal proteins (connective tissue or insoluble)
 These proteins function as a supporting framework for the living body
(1) collagen
 principal component of the connective tissue fraction
 present in horns, hooves, bone, skin, tendons, ligaments, fascia,
cartilage and muscle
 major factor that influence the tenderness of the muscle after cooking
(2) elastin
 these proteins are extremely unreactive and form as a minor component of
most tissues but is found in appreciable amounts in the ligaments of the
vertebrae and in the walls of large arteries where these provides elasticity
c) sarcoplasmic protein (water soluble)
 These proteins are found in the sarcoplasm or the fluid surrounding and bathing
the myofibrils.
 They are also called water-soluble proteins because they are commonly extracted
with water or low ionic strength of salt solutions.
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
They are effective emulsifiers of fat in sausages.
(1) pigments
 this helps to contribute to the red color of the muscle (myoglobin)
(2) enzymes
 occur naturally in muscle tissue and contribute to function during the
aging of meat
 these enzymes are responsible for degrading protein, carbohydrates and
fats in meat
3) Nitrogenous extractives
 Related to proteins (but are not true proteins) and these are the nitrogenous substances
and nucleopeptides
 These are water soluble components that excite the flow of gastric juices when cooked
meat is ingested
 Along with fat, it provides much of the aroma and flavor of meat; also responsible for the
so-called “gamey (intense) flavor” of meat of wild animals
e.g. creatinine, creatine, purine and free amino acids
4) Fats (triglycerides)
 External depots contain more unsaturated fatty acids than internal depots
 Lamb fat is more saturated than beef fat while pork fat is less saturated than beef fat.
 Fat content of the carcass is highly variable and inversely related to the moisture level.
5) Carbohydrates
 The primary carbohydrate reservoir (glycogen) of the animal’s body is the liver (half of
those found in the body) and half is found all throughout the body in muscles
 Glycogen serves an important function in controlling muscle pH which is the net effect of
the extent of glycolysis.
 The amount of glycogen in postmortem meat is quite low or even completely absent so it
has little effect on the nutritive value of meat and meat products but it plays a major role
in determining the physical properties of meat.
6) Vitamins and minerals
 Meat is a significant source of iron, zinc, phosphorus and most of the B-complex
vitamins (B1, B2, niacin, B6 and B12)
B. Slaughtering of Animals
1. Selection of animals for slaughter
Some of the general factors that should be considered are the following:
a. Age of the animal
The recommended ages of livestock for slaughter :
1) swine – 6-12 months of age
2) cattle and carabao – 3 years or younger
3) goat – about a year old
Meat coming from old animals is dark, rough textured but flavorful, have high water
binding capacity and emulsion capacity and associated with high degree of marbling.
Tenderness changes with age.
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In general, meat from old animals is juicier than meat from young one. Young animals
have watery meat on first chewing but have a final impression of dryness.
b. Sex of the animal
1) barrows and gilts – best sources of meat for curing
2) boars – young boars (200 days old or below) can still be used. As the boar becomes
older, “boar taint” becomes pronounced
3) sows – meat is tough and during advance stage of pregnancy the meat
maybe fishy in odor.
c. Size
The recommended slaughter weights of animals for fresh meat retailing and intact meat
processing are:
1) hog – 80-110 kg
2) cattle and carabao – 300-450 kg
In terms of processing characteristics, the processing, smoking and storing, shrinkage of
loin, ham and bacon tend to decrease with increase slaughter weight but the percentage
cooking losses increase with increasing live weight.
d. Degree of fatness
Meat flavor, tenderness and juiciness are some of the palatability factors greatly
influenced with fat. Most flavor compounds are found in the fatty tissue while chewing fat
stimulates the flavor of saliva thus, giving the impression of juiciness. For sausages and other
comminuted meat products, 30-40% fat seems to be the most acceptable.
e. Health of the animal
The animal for slaughter must be substantially healthy. Unhealthy animals must be first
treated and brought to normal condition prior to slaughter.
2. Management of Animals Prior to Slaughter
Some of the recommended management practices for animals prior to slaughter are the
following:
a. Fasting
Fasting as applied to slaughter animals is simple the withdrawal of feed but water is
given ad libitum. Pigs are fasted for 12-24 hours and ruminants for 24-48 hours. Fasting the
animals has several advantages:
1) saving of feeds
2) ease of cleaning entrails
3) ease of cleaning and eviscerating carcass
4) it results to a thoroughly bled and brightly colored carcass
5) it lengthens shelf-life of carcass
6) it gives low shrinkage of meat
b. Relax the animal
As much as possible, no form of stress is given to animals prior to slaughter. If stress
cannot be avoided, animals must be given enough time to relax and regain their composure
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before these are slaughtered. One to three days’ relaxation in the holding pen is enough to
remove the effects on the animal depending on the degree of stress.
If stress given is not so severe, pork tends to be pale, soft and exudative (PSE). If stress
given is severe, meat tends to be dry, firm and dark (DFD).
The level of glycogen on the muscles at death controls the pH of the resulting meat.
Meat from unstressed animals has a pH of 5.3 and the drop in pH is very gradual. The meat
from stressed animals, pH is usually within the range of 6-7 and the pH drop is very rapid. The
rapid pH drop is partly due to the rise in the temperature of the carcass favoring rapid anaerobic
glycolysis.
c. Handle the animals gently
The part of an animal whipped, kicked or boxed prior to slaughter develops blood clots
and red spot in the meat. This is due to breaking of blood vessels in those areas. As a result,
the blood is not withdrawn during bleeding and this is a good medium for luxuriant growth of
microorganisms, which causes accelerated spoilage of the meat. Meat with blood clot and red
spots when used for intact meat processing nearly always spoils before curing period is
completed.
d. Clean the animals
The practice of good sanitation is best started by keeping the animal clean. One of worst
contaminants of meat is the microflora most abundant in the feces. These and other dirt must
therefore be washed off to minimize possible contamination of the carcass.
3. Basic Requirements of Slaughtering
There are four basic factors to be considered in slaughtering animals:
1) cleanliness of the meat produced
2) hygiene of production
3) efficiency of meat inspection
4) adequacy of meat preservation
4. The Slaughter House
Slaughterhouse – also called abattoir (from the French verb abattre, "to strike down"), is a
facility where animals are killed and processed into meat products.
Prerequisites of a good slaughterhouse (based on NMIS)
 Complete facilities for the proper care of animals prior to slaughter
 Lairage areas and holding pens should be wide enough
 Adequate ventilation and water must be provided at all times
 Separate rooms for the slaughter of hogs and ruminants
 Separate rooms for handling meat and offals
 Presence of facilities for hanging carcasses, refrigeration units and water supply
Water requirement for slaughtering animals:
a. 60 gallons per head of cattle and carabao
b. 30 gallons per head of hog
c. 15 gallons per head of goat
d. 7 gallons per head of chicken
 Must have good drainage
 Must be far from residential houses and not located near the highway
 Must have an adequate pollution control device
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5. Ante-mortem and postmortem inspection of slaughtered animals
The animal has to undergo ante-mortem inspection for the detection of diseases and
defects. It is only after authorized meat inspector declares the animal fit that it should be
slaughtered. Likewise, during the ante-mortem inspection, the origin, sex and legality of
slaughtering the animal are checked.
a. Ante-mortem inspection
An ante-mortem examination and inspection is made for the purpose of eliminating those
animals that are unfit for the preparation of food. Such inspection is done at the day of
slaughter. Animals plainly showing symptoms of a disease or condition that would cause
condemnation of their carcasses on post-mortem inspection are marked “condemned” and are
killed by the official establishment in a manner prescribed for condemned carcasses. Any
animal that does not yet plainly show symptoms of such diseases but which is suspected of
having a disease or condition that may cause condemnation of part or the entire carcass upon
post-mortem inspection is marked “suspect”. Its identity is maintained during the slaughter
process until a final post-mortem inspection is performed.
b. Post-mortem inspection
A careful inspection and examination is made simultaneously with the slaughtering and
dressing operations. The post-mortem inspection is conducted under the supervision of a
veterinary medical officer. Inspectors are located at specific stations along the dressing line so
that the carcass, head and viscera of each animal can be inspected. If the carcass or part is
finally found to be unwholesome or unfit for human food, the veterinarian marked them
“condemned”. If they are found to be wholesome and fit for human food then the inspector
allows them to reenter the production line and marks them “inspected and passed”. In cases
where the lesion or condition is localized, the inspector condemns the affected part and may
pass the remainder of the carcass.
6. Slaughtering Procedure
a. Salughtering of Swine
Steps in slaughtering swine:
1) Stunning
It is done to make the animal unconscious without killing it and to make restraining easy
and sticking humane.
Methods of stunning:
a. electric shock stunning - consists in applying electricity through the animal’s brain,
using two electrodes to induce an epileptic shock, or through the heart.
b. captive-bolt or pneumatic pistol - applied to the forehead; captive-bolt pistols eject
a metallic cylinder through the animal’s skull and return to their original position
for the next shot. Alternatively, pneumatic pistols impact the animal’s head
without penetration.
c. carbon dioxide - stunning action of carbon dioxide is accomplished by blockade of the
animal’s neural terminals, therefore reducing the nervous impulses. Carbon dioxide
concentrations of 65% to 70% during 45 seconds work most efficiently.
2) Sticking
It is a term for bleeding. The knife is held at a 35 to 40 degree angle and thrust under the
breastbone. A thrust and a withdrawal are made to cut the jugular veins and carotid arteries.
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3) Scalding and scraping
The temperature of the scalding water is very important for successful scraping
procedure. The water must be maintained at 54 to 82ºC (130 to 180ºC) but temperature
between 60 to 71ºC is optimal.
4) Removal of the head
The head is cut off about two to three fingers from the base of the ears. The bone
connection is severed at the atlas joint by applying a sudden jerking twist at the head.
5) Evisceration
It refers to the removal of the visceral organs from the opening of the carcass up to the
complete removal of the internal organs from the body cavity.
6) Splitting
It is done at the center of the chine bone to be able to produce uniform pork chops from
the carcass
7) Chilling
The carcass is chilled at 0 to 4ºC for 24 hours. Temperature of 2ºC is very ideal so that
firmness and condition of the carcass is ideal for fabrication.
b. Slaughtering Cattle and Carabao
Slaughtering cattle and carabao is similar to slaughtering hogs in some aspects.
Steps in slaughtering cattle and carabao
1) Stunning
Some of the stunning equipment that can be used includes matador, stunning gun,
carbon dioxide chamber, sledgehammer etc. The animal is hit immediately after the head bones
or right at the center of the atlas joint. With one blow at this site, the carabao or cattle loses
consciousness and falls down.
2) Sticking
The animal must not be down for more than two minutes because increased blood
pressure may break the capillaries and cause an unattractive condition in the meat.
A portion of the hide at the upper neck when the animal is laying flat on one side is
skinned out to act as receptacle for blood. The knife is inserted at 45º angle in front of the
brisket and the carotid arteries and jugular vein are severed in a similar manner as in the hogs.
The blood is scooped out with a cup from the flapped hide receptacle. To induce thorough
bleeding, an operator may step at the flank of the animal rhythmically.
3) Flaying and skinning
This refers to the removal of the hide.
4) Removal of the shank and head
To remove the head, a cut is made around the neck at the atlas region and the head is
twisted off. The shanks maybe removed at the flat joint between the tarsal and metatarsal bones
at the hind shank and between the carpal and the metacarpal bones of the front legs.
5) Evisceration
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6) Splitting/Quartering
This is the process of dividing the carcass into two along the vertebral column. As much
as possible, the left and the right sides must have the same weight. After splitting, the carcass is
quartered by cutting each side between the 12th and 13th ribs.
7) Shrouding
This is the process of wrapping the carcass with cheesecloth. The cloth is soaked in
lukewarm water (about 45ºC) and wrapped around the carcass while it is warm. The shrouding
cloth absorbs remaining blood at the surface of the carcass, smoothens the external fat
covering, causes the fat to appear white and dense and prevents excessive shrinkage and
oxidation.
8) Chilling
The required chilling period is 48 hours but maybe extended from 7 to 14 days for aging
purposes.
c. Slaughtering of Sheep and Goat
There are two methods of slaughtering goat and sheep in the Philippines. One is the
singed method and the other is the flayed method
Steps for slaughtering goat and sheep
1) Stunning
This procedure can easily be accomplished with the use of ordinary carpenter’s hammer.
A properly stunned goat lay flat on its side almost motionless.
2) Sticking
Then the lower jaw is grasped with the hand and the head is pulled back. With the back
positioned towards the cervical bones, the knife is inserted at the back of the jaw as close as
possible to the backbones. At this position, the outward portion of the neck is cut clear and
through severing the blood vessels, the windpipe, gullet and fleece.
3) Singeing or Flaying
In this method a blowtorch or an open fire can be used. While singeing, the hairs are
continuously scraped with a dull knife or with a piece of stick.
With flaying, the hind legs are tied with a rope and the carcass is suspended in a
convenient hanger or branch. Knife is used to start the flaying process. It starts with the hindlegs
followed by the forelegs. The head of the animal is removed at the atlas joint and the pelt is
stripped by forcing it downwards.
4) Evisceration and chilling
The carcass is not split and the breastbone is not opened. Chilling is done for 24 hours
at 0 to 4ºC before fabrication.
7. Average dressing percentages of slaughtered livestock animals
1) cattle/carabao – 60%
2) calves – 62%
3) hogs – 73%
4) sheep/goat – 50%
5) chicken – 75%
6) turkey – 83%
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7) duck – 70%
8) geese – 75%
8. Kosher and Muslim meats
Both the Jewish and Muslim faiths have specific requirements for the slaughter of religiously
acceptable animals. All kosher meat comes from animals that have split hooves, that chew
their cud and that have been slaughtered in a manner prescribed by the halachah (Orthodox
Jewish law). Meat from undesirable animals or from animals not properly slaughtered or with
imperfections is called nonkosher (trefah).
Kosher slaughter, inspection and supervision are performed only by trained individuals
approved by rabbinic authority. Only the frontquarters are identified as kosher, as the
hindquarters contain the forbidden sciatic nerve, which is embedded deep in the muscle tissue
and is difficult to remove. Hindquarters are sold as nonkosher meats.
Any Muslim may slaughter an animal while invoking the name of Allah. In cases where Muslims
cannot kill their own animals, they may use meat killed by a “person of the book”, e.g. a
Christian or a Jew. Usually this Halal slaughter is done by regular plant workers while Muslim
religious leaders are present and reciting the appropriate prayers.
C. Fabrication and Identification of Cuts
1. Meat fabrication defined
Meat fabrication – is the cutting of carcass into standard wholesale and retail cuts.
Proper fabrication leads to:
 Lowering of cutting losses
 Making buyers conscious of what they are buying
 Giving confidence to both producers and consumers
2. General principles of fabrication:
 Tender meat is separated from tough meat
 Thick portion must be separated from the thin portion
 Muscles are cut across the grain or meat fibers so that the grain breaks and separates
fast while chewing.
 Cheap parts must be separated from the expensive parts.
3. Importance of bone structure in meat fabrication
 It acts as a guide in cutting carcasses
 Serves as a clue to the tenderness of the cut
 Majority of the wholesale and retail cuts are identified and named after the bone present
 Examining the bone could identify if the animal is old or young
4. Beef and carabeef carcass fabrication
Wholesale cuts of the frontquarter
1) Ribs – include the portion of the back bounded by the 6th and 12th ribs
2) Plate or short plate – thin portion of the frontquarter and lies opposite the ribs
3) Brisket – piece containing the sternum
4) Foreshank – portion below the arm and elbow joint
5) Chuck – shoulder portion and includes the parts of the blade bone, arm bone, five ribs,
thoracic vertebrae and neck bones.
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Wholesale cuts of the hindquarter
1) Flank – it contains part of the 13th rib and the abdominal muscle
2) Loin – it contains the back bone which consists of the spine bone (spinous process), chine
body (body of the vertebra) and finger bone (transverse process)
3) Round – this contains the hindshank and bone of the thigh
5. Pork carcass fabrication
Three categories of pork cuts
1) lean cuts – composed of the ham, loin and shoulder
2) primal cuts – composed of the ham, loin, belly and shoulder
3) miscellaneous cuts – composed of the pig’s feet, tail, fat and lean
trimmings, neckbones and spareribs
Wholesale cuts of pork carcass
1. shoulder
2. ham
3. loin
4. belly or side
6. Goat and sheep carcass fabrication
The fabrication procedure for goat carcass suggested here is revised from the standard
fabrication system for lambs used by the Americans. There are five cuts derived from goat
carcass:
1) Leg – it is separated by a cut at the tip of the pelvic bone perpendicular to the underline when
the carcass is extended. The posterior portion of the carcass is the leg.
2) Loin – it is the region of the carcass from the tip of the pelvic bone to the 12th rib
3) Rib – it is the cut from the point where the loin is separated and between the third and fourth
rib
4) Shoulder – it includes the regions from the third rib and second cervical vertebra. The shank
portion is included in this cut.
5) Neck
D. Meat Identification
Normal meat color from common livestock carcasses
Species
Beef
Pork
Carabeef
Chevon
Normal lean color
Bright cherry red to dark red
Grayish pink to grayish red
Dark red
Light red to bright red
Veal
Horse
Pinkish
Bright red
Normal fat color and consistency
Cream white to yellow, firm and dry
White and greasy
Flinty white
Chalk white, appears brittle and
dense
Seldom have fat, cream
Cream to yellow, usually soft
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The criterion of lean color for species identification is however, unreliable because the color
pigment is highly reactive to oxygen and highly sensitive to dehydration.
Within species, the more dehydrated and the longer the meat is exposed to air, the darker the
color is. Lean meat from old animals is darker than lean meat from young animals.
E. Meat preservation
1. Meat preservation defined
Meat preservation is lengthening the storage life of meat by the application of processes to
delay meat spoilage. Any method that can contradict the forces of meat deterioration is a good
preservation method but its application to meat must be done as soon as possible. Meat
deteriorates very fast under normal room condition.
The causes of meat spoilage are biological, physical and chemical forces. Among the forces of
deterioration, the biological are the most prevalent and the most destructive.
Causes of Meat Spoilage
1. Biological causes of meat deterioration
This is brought about by microorganisms, flies, rodents and cockroaches. Among the biological
forces, microbiological spoilages are the most severe and account for almost 99.9% of all the
biological deteriorations.
The organisms which spoil meat may gain access through infection of the living animal or by
contamination of the meat post-mortem. External contamination of the meat is a continuing
possibility from the moment of bleeding until consumption.
Symptoms of microbial spoilage include: Ammonia or sulfur smell odor, tallow or chalky
taste, slime formation, rancid flavor, color change, sticky meat surface, whiskers, souring and
putrefaction.
Growth requirements for the different microorganisms causing spoilage in meat are the most
important consideration in the inhibition of growth. Growth inhibition then can be achieved by
withholding one, two or all the required conditions and nutrients for growth. Majority of the
present day preservation methods are based on this principle. The following are the growth
requirements of microorganisms:
a. Moisture content - The amount of water that is available in food is expressed in terms of
water activity (aw), where the aw of pure water is 1.0. Generally bacteria dominate in
foods with high aw (minimum approximately 0.90 aw) while yeasts and molds, which
require less moisture, dominate in low aw foods ( minimum 0.70 aw).
b. pH - Most microorganisms have approximately a neutral pH optimum (pH 6-7.5). Yeasts are
able to grow in a more acid environment compared to bacteria. Molds can grow over a
wide pH range but prefer only slightly acid conditions.
c. Available Oxygen - Microorganisms can be classified according to their oxygen
requirements necessary for growth and survival:




Aerobes: oxygen required
Facultative anaerobes: grow in the presence or absence of oxygen
Microaerophilic: grow best at very low levels of oxygen
Aerotolerant Anaerobes: oxygen not required for growth but not harmful if present
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
Anaerobes: grow only in complete absence of oxygen; if present it can be lethal
d. Temperature - According to temperature, microorganisms can be placed into three groups:
 Psychrotrophs: optimum growth temperatures 20 to 30° capable of growth at
temperatures less than 7° C. Psychrotrophic organisms are specifically
important in the spoilage of refrigerated products.
 Mesophiles: optimum growth temperatures 30 to 40° C; do not grow at refrigeration
temperatures
 Thermophiles: optimum growth between 55 and 65° C
2. Chemical causes of meat deterioration
a. enzymatic action
Enzymes are problem substances, which will help speed up chemical reaction. This may
be reduced or totally stopped by subjecting the meat to a temperature below or above the
temperature range needed for the activity of the meat enzymes.
b. oxidation
This chemical reaction is popularly known as rancidity. For rancidity to develop, light, air
and free fatty acids must be available. If one of these is missing, rancidity does not occur. At
present, rancidity can be delayed by vacuum packaging of products and by adding antioxidants.
c. discoloration
Any deviation from the normal color of the meat muscle maybe described as
discoloration. Discolorations are usually associated with chemical changes in the muscle
pigments primarily in myoglobin. Discoloration is usually due to the presence of metmyoglobin,
which contributes the brown or grayish brown color of fresh and processed meat.
3. Physical causes of meat deterioration
a. dehydration
The loss of moisture from meat surfaces during storage produces a dried, stale, coarse,
textured appearance that adversely affects eye appeal and acceptability. Severe dehydration
usually results in a very dry product following cooking, and thus, it can affect palatability of meat
as a food.
b. freezing and thawing
During freezing storage an excessive loss of moisture from meat surfaces will result in
localized areas of dehydration and discoloration. This harmless phenomenon is called freeze
burn. It can result when the wrapping material has been punctured or when moisture proof
wrapping is not used.
The physical damage caused by slow freezing results in a considerable loss of fluid from
the meat when it is thawed. This fluid will collect in a package upon thawing and is called drip.
c. shrinkage under refrigeration
During refrigerated storage, meat loses moisture from its surfaces, resulting in a weight
loss called shrink. Other physical changes that accompany prolonged refrigeration of meat
include surface dehydration and discoloration.
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METHODS OF MEAT PRESERVATION
The principles underlying meat preservation include:
1. removing and keeping the microorganisms out (asepsis)
2. hindering the growth and activity of microorganisms
3. killing the microorganisms
4. destroying and inactivating food enzymes
For preservation method to be effective, the meat must be sound and must contain low
microbial load. It should counteract or stop the action of forces of meat deterioration. These are
the following methods of meat preservation:
Temperature Control
 Freezing
 Chilling
 Thermal Processing
Moisture Control
 Dehydration
 Drying
 Freezedrying
 Curing
 Smoking
Direct Microbial Inhibition
 Ionizing radiation
 Antibiotics
 Chemical preservatives
1. Temperature Control
a. Low Temperature Processing
1) Chilling
Chilling is subjecting meat to a temperature between 0-4ºC. This temperature can affect rapid
cooling of the meat but does not cause hardening and freezing of meat juices.
Factors to be considered in chiller storage
(a) temperature
Meat is recommended to be chilled as near as freezing point as possible. For home
refrigeration the temperature is 40-50ºF (4-10ºC) and for commercial refrigeration it is 36-38ºF
(1-4ºC).
(b) relative humidity and ventilation
The recommended relative humidity for meat storage at:
0ºC – RH 92%
2ºC – RH 88%
4ºC – RH 75%
Very low relative humidity causes the loss of moisture and weight of the products being
stored. Too high relative humidity on the other hand, favors growth of spoilage organism.
Ventilation helps maintain a uniform relative humidity, removes odors and helps prevent
development of stale odors and flavors.
(c) composition of storage atmosphere
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The atmosphere in the storage cabinet is seldom altered but pumping carbon dioxide
into it lengthens the storage life of meat in the chiller.
2) Freezing
This refers to the process of exposing meat to a temperature range of (-32ºF) resulting
to crystallization of water in the tissues.
Types:
(a) quick freezing – infers a freezing of 30 minutes or less. This is usually attained at a
temperature range of (-15ºC) to (-46ºC).
(b) slow freezing – freezing of the meat takes from 3-72 hours usually at (-15ºC) to (-29ºC).
Advantages of quick freezing:
 Less mechanical destruction of meat cells
 Less time for diffusion of soluble materials and separation of ice
 There is more prompt inhibition of microbial growth
b. Thermal Processing
1) Blanching
Applied to inactivate the enzymes before further heat treatment (65°C)
2) Cooking
Applied to improve the sensory characteristics of meat (85°C)
3) Canning
This is the hermetic or airtight sealing of foods in cans or jars at 212ºF (100ºC) at 10-15 pounds
pressure for a specific period of time.
a) Pasteurization - destroys pathogenic vegetative cells but certain heat resistant
microbes and spores can survive. Products subjected to this treatment require
refrigeration.
b) Sterilization - destroys both microorganisms and spores but affects the quality of meat
to a considerably greater degree. Meat is subjected under pressure at temperature
above 110°C. These products are shelf stable and need no refrigeration.
2. Moisture Control
a. Drying
The method involves the reduction of the original water content.
Two ways of drying:
1) natural drying (drying)– natural sunlight is used to reduce the moisture content of meat
2) artificial drying (dehydration) – a chamber equipment with heating elements maintained at
a temperature of 110-120ºF and relative humidity of 85% is used for drying
b. Freezedrying
Removal of water from meat by sublimation from the frozen state
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c. Smoking
This is a process of subjecting meat to smoke produced by burning wood or sawdust.
Two methods:
1) natural smoking – exposure of the meat to wood smoke which causes the deposition of
phenolic and pyroligneous compounds on the meat surface that acts as
preservative and flavoring agent
2) artificial smoke (liquid smoke) – smoke flavor is incorporated in the pumping pickle for ham
and bacon.
d. Salting
This is a simple method of dehydration in which the salt caused the withdrawal of water from the
tissue of both the meat and the spoilage organisms resulting to the shriveling and plasmolysis of
bacterial cells. Salt also ionizes to yield chlorine ion which is harmful to organisms. Salted meat
becomes tough, shriveled and loses some of the important meat flavor.
e. Curing
This refers to the application of salt, sugar, nitrates and other preservatives and adjunct to
prolong the keeping quality of the product. Curing ingredients inhibit the growth of
microorganisms.
f. Pickling (pickle curing)
In pickle curing, curing ingredients are mixed in water to form a pickle solution. This solution can
be introduced into the meat in any of the following ways:
1) stitch pumping – a single needle with multiple openings or multiple needles with single
opening maybe used to inject the solution into the meat
2) artery pumping – solution is injected into an artery and distributed throughout the cut via the
vascular system
3) tumbling or massaging – utilizes a machine that resemble a concrete mixer to tumble or
massage cuts as they are cured.
4) vat curing – meat is submerged in a vat containing pickle solution until the solution
completely penetrates the meat.
Basic ingredients for curing meat
1. Salt
Salt is basic to all curing mixtures and is the only ingredient necessary for curing. It is an
important ingredient in the preparation of meat emulsions for imparting the typical flavor and
texture of processed meats and to contribute to keeping quality by preventing the growth of
putrefying bacteria. The salt component of most processed meats ranges between 2.5 to 3.0
percent of the final product. In addition, salt alone results in a dark, undesirable colored lean
that is unattractive and objectionable to consumers.
2. Sugar
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It adds flavor, helps overcome saltiness and counteracts the toughening effect of salt. Sugar
also interacts with the amino groups of the proteins and when cooked, forms browning products
that enhance the flavor of cured products. It aids in the lowering of pH of the cure by providing
food for some of the lactic acid fermenting bacteria that develop the characteristic flavor of some
dried cured products. It can also reduce the shelf life of the meat by providing food for spoilage
bacteria, yeasts and molds. Corn syrup, molasses and other natural sugar substitutes are
sometimes used in place of sugar.
3. Nitrates and nitrites (curing salt)
Nitrates and nitrites are curing ingredients.
The function of nitrite in meat curing includes:
a. to stabilize the color of lean tissues
b. to contribute to the characteristic flavor of the meat
c. to inhibit growth of a number of food poisoning and spoilage microorganisms (
Clostridium botulinum in canned products)
d. to retard development of rancidity
Nitrate itself is not effective in producing the curing reaction until it is first broken down into
nitrite. This is a slow process that depends upon the presence of bacteria in brine and meat.
Therefore, nitrate has largely been replaced by nitrite.
Nitrite provides the ultimate source of the nitric oxide that reacts with the myoglobin pigment of
the muscle tissue. Levels in excess of 200 parts per million (0.02%) of sodium nitrite should not
be used. Nitrates have been implicated in the formation of cancer-producing substances (called
nitrosamines) in meat under certain circumstances.
4. Phosphates
This is adjunct that is used to increase the water holding capacity of cured products. With
increase water holding capacity, product yield increase, and product surface is drier and firmer..
As cured products containing phosphates loss moisture after processing, the phosphates may
precipitate out on the surface forming “whiskers” or phosphate crystals. Excessive levels have
been accused of causing soapy taste.
5. Ascorbates/Erythorbates
Ascorbates serve three functions:
a. take part in the reduction of methmyoglobin to myoglobin thereby accelerating
the rate of curing
b. it reacts chemically with nitrite to increase the yield of nitric oxide from nitrous
acid
c. excess ascorbate act as antioxidant, thereby stabilizing both color and flavor
d. under certain conditions ascorbates have been shown to reduce nitrosamine
formation
Examples are ascorbic acid, erythorbic acid, sodium ascorbate, citric acid and sodium citrate. It
should be used not more than 500 parts per million (0.05%) of the mixture.
6. Extenders/Binders/Filters/Emulsifiers
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Extenders in general are added to lower quality products for economic reasons. Some of them
improve binding properties, cooking yields, slicing characteristics and flavor.
Binders are proteinaceous agents that improved water-binding properties of comminuted meat
products. Fillers are carbohydrate products which absorbed extensive quantities of water.
However, they are not good emulsifiers. Extenders are nonmeat materials, add in an amount
that they are able to increase the bulk or modify the quality of sausage or meat loaf products. It
is usually plant protein. Most extenders are usually limited to 3% in the dry state or to 10% after
swelling.
7. Seasoning
Seasoning is a comprehensive term for ingredients, which improve the flavor of processed
meats.
Spices are aromatic substances of vegetable and yhey vary in composition. Spices increase
zest and product variety to the diet. They also stimulate the flow of digestive secretion thereby
aiding digestion.
Condiment herbs include sage, savory, bay leaves, thyme and marjoram. The dried leaves of
any of them can be used in the preparation of sausages and other meat products. Condiment
vegetables are onion and garlic.
8. Other ingredients
Anisado wine, monosodium glutamate (MSG) and soy sauce are added to further improve the
flavor of the product.
3. Direct Microbial Inhibition
a. Irradiation
The use of radiation that have wavelengths of 2000Å or less in order to destroy microorganisms
in and on meat without raising the temperature of the product. This process is called cold
sterilization.
b. Use of Antibiotics
Since their effect is bacteriostatic it is more effective where the total bacterial population is low.
Since they do not sterilize food, they delay rather than prevent spoilage. There is possible
development of resistance of microorganism in meat. Lactic acid bacteria (LAB) can produce
several antimicrobial compounds including organic acids, carbon dioxide, bacteriocins that may
play a role in meat preservation and could be used as alternative for chemical preservatives.
c. Use of Chemical Preservatives
A chemical preservative is any substance which is capable of inhibiting, retarding, or arresting
the process of fermentation, acidification or other deterioration of food or of masking any
evidence of putrefaction. Examples: nitrite, nitrate, sorbic acid, acetic acid.
F. Classification of Processed Meat
Processed meat maybe defined as meat that has been changed by any mechanical,
chemical or enzymatic treatment, altering the taste, appearance and often the keeping quality of
the product.
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Classification of processed meat
a. Sausages (comminuted products)
b. cured whole muscle cuts (non-comminuted products)
c. restructured meat products
1. Sausages
These are comminuted, seasoned meat that maybe cured, smoked, molded or heat processed.
The numerous varieties of sausages necessitate several and slightly different processing
procedures. The meat can come from beef, veal, pork, lamb, poultry or combination of these
sources.
Types:
a. Fresh sausage – made from comminuted meat and are not cured, smoked or cooked. These
must be kept under refrigeration and must be cooked before serving. Some examples
are fresh pork sausage, hamburger and chorizo
b. Uncooked sausage – similar to fresh sausage, except that the meat is subjected to a mild
cure. Then, it is placed in natural casing or wrapped in plastic. Such products should
be kept under refrigeration and cooked before serving.
c. Uncooked and smoked sausage – this sausage may include cured meat but not cooked
meat. It is smoked after placing in edible casing but must be cooked before serving. Smoked
pork sausage (smoked longanisa) and smoked country-style sausage are examples.
d. Cooked sausage – usually made from meat that has been cured and cooked. This sausage
is ready to eat, although some may be heated before serving. Types of cooked sausages
include braunschweiger (liver sausage) and blood sausage.
e. Cooked and smoked sausage - this is the most popular type of sausage. Product is usually
made from meat that has been cured, formed into sausages, cooked and subjected to a light
smoke. This type of sausage is ready to eat, although some may prefer to heat certain kinds of
this product before serving. Examples are bologna, frankfurters and Vienna sausage.
f. Dry sausages
1) dry sausage – this type of sausage losses about 25-40% of its original weight through
processing and drying. Example: chorizo de bilbao, hard salami
2) semi-dry sausage – this sausage losses 8-15% of its original weight through
processing and drying. Example: canton sausage
3) fermented dry and semi-dry sausages – these sausages are similar to the dry
sausages except that acid-forming microorganisms such as lactobacilli are deliberately
added in quantities and in conditions where they outgrow other organisms and produce
desirable acid flavors as well as provide added protection against spoilage. Example:
pepperoni
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g. Loaves and other specialty meat – these products are chopped-meat mixtures, possibly
containing extenders and other ingredients and processed in the form of a loaf. This type of
sausage need not be cooked before serving. Examples of luncheon meat and meat loaf.
2. Cured whole muscle cuts
Whole muscle cuts like ham, corned beef, pastrami and bacon are considered processed meat
products because they have been treated with a curing solution, dry cured, smoked and/or
seasoned. These products are more popular in their processed form than as fresh cuts.
a. ham – defined as the hindleg of pork that has been cured and smoked or cured and
canned
b. corned beef – the brisket is the most popular cut of meat used for corned beef, although
beef round is also used. Formerly, “corning” referred to the process of preserving beef
by sprinkling it with grains (corns) of salt. Today, corned beef is cured with pickle
solution consisting of water, salt, sugar, nitrite and spices.
c. bacon - it is produced primarily from pork bellies. Beef bacon is made from the boneless
beef short plate. Canadian style bacon is made from top loin muscle of pork – usually
that from heavier hog. These are cured and smoked giving them their unique flavor.
d. pastrami - made from the brisket, plat or top round muscle of beef. After dry curing with
salt, the beef is washed, and then rubbed with a paste of garlic powder, ground cumin,
red pepper, cinnamon, cloves and allspice. It is then smoked and cooked
4. Restructured meat
Restructured meat products are generally made from flaked, ground or sectioned beef or
pork, which is shaped into roasts, steaks or loaves. Examples of restructured meat are smoked
sliced beef and most boneless hams.
The process of restructuring consists of three steps: a reduction or modification in
particle size, blending and reforming into the desired product size and shape. Some
restructured hams look very similar to their whole muscle counterparts. In fact, some are simple
chunks of ham that have been bound together to form a larger piece.
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