Lecture about meat processing and preservation Meat class lecture.

1. Meat
 ‘Meat is the post-mortem aspect of the 300 or so
anatomically distinct muscles of the body, together with
the connective tissue in which the muscle fibres are
deposited and such intermuscular fat as cannot be
removed without disrupting the muscle as a whole’.
 Meat refers to the skeletal muscle from the carcasses of
animals – cattle (beef), pork and lamb (sheep).

2. General Composition of Meat
• 20% protein
• 8% fat
• 1-2% glycogen (carbohydrate)
• 1% ash
• 70% water

13. Rigor mortis (Latin: rigor "stiffness", mortis "of
death")- is one of the recognizable signs of
death, caused by chemical changes in the
muscles after death, causing the limbs of the
corpse to stiffen after death.

16. • Resolution of rigor:
The stiffness in the muscle tissues begins to
decrease owing to the enzymatic breakdown
of structural proteins (i.e., collagen) that hold
muscle fibres together. This phenomenon is
known as resolution of rigor and can continue
for weeks after slaughter in a process referred
to as aging of meat.

31. • Cooling
– Used to slow or limit the growth of microorganisms --- the lower the temperature, the
slower the microbial growth
– Shelf life estimates (varies by species, level of hygiene practiced, equipment used):
» Properly refrigerated and packaged retail meat – approximately 72 hours
» Ground meat – about 24 hours
» Vacuum packaged and refrigerated meat – approximately 3 weeks
» Vacuum packaged and refrigerated cured meat – about 2 months
• Freezing
– Most common method of preserving fresh (uncured) meat
» Mostly done by consumers after purchase
» Not as popular with cured meat as with fresh meat because cured meat is more
susceptible to oxidative and texture changes when frozen
» Cooked meats tend to develop off-flavors when frozen
– Meat freezes at about -2˚C (28˚F)
– Freezing does not kill microorganisms but inactivates meat enzymes and inhibits the
growth of spoilage organisms
– Recommended temperature for frozen meat is -18˚C (0˚F)
– Four important phases: pre-freezing (quality of the meat and preparing it for freezing –
i.e. size and shape of an item and packaging), freezing, frozen storage (potentially the
most damaging phase to the quality of the meat; growth of ice crystals can occur
resulting in structural damage), and thawing (outside may be at ambient temperature
while the inside is still frozen; potential for microbial growth on the surface)
– Foods with lower water content freeze better and will retain more quality after freezing
(less cellular damage due to ice crystals)

32. • Drying
– Removal of water to the point that available water is not
sufficient enough to support microbial growth
– Extremely lean meat is the most desirable for drying
– Often involves a cooking step before drying
– Drying may be accomplished by:
» Low-temperature drying (less than 120˚F)
» High-temperature drying (greater than 200˚F)
» Freeze-drying
» Salting
• Irradiation
– Meat is exposed to a controlled amount of radiation for a specific
time to destroy spoilage organisms
– Pork and poultry were first meats to be approved by the USDA
and FDA to be irradiated

33. • Packaging
– Packaging is critical to overall preservation process; meat must be properly packaged
after processing for preservation techniques to be successful
– Packaging is most often something used to enclose the meat in order to protect the
desirable properties inherent or imparted to it (Cassens, 1994)
– Packaging protects products against deteriorative effects including discoloration, off-
flavor and off-odor development, nutrient loss, texture changes, pathogenicity and other
measureable factors (Zhou, Xu, & Liu, 2010, p. 123)
– Canning and radiation techniques include the package as an essential factor in
preservation
– Packages suitable for meats include:
» Wax- or paraffin treated kraft paper
» Aluminum foil
» Laminated foils
» Films
– Factors affecting suitability for packaging meat include (Romans et al., 2001):
» Have low moisture-vapor transmission
» Have differing oxygen permeability
» Are puncture resistant
» Are pliability
» Will maintain strength and pliability at sub-zero temperatures
» Are non-toxic
» Are odorless
» Are easy to mark for identification
» Will peel from the meat when frozen (good stripping qualities
» Are greaseproof and stain proof
» Provide good sealing properties

34. 2. Chemical Methods of Preservation
• Curing
– Salt
» Salting is the oldest known method of preserving meat; it is
believed that the ancient Sumerian culture (3,000 B.C.) was the first
to use salt to preserve meat and fish
» Major ingredient in curing
– Nitrate and Nitrite
» Sodium nitrite is vital to curing process because it reacts with
myoglobin to produce the color characteristic of cured meat
– Sugar
» Used for flavor function and to moderate the harsh flavor
associated with high concentration of salt
– Reductants
» Speed up the curing process and make it more uniform
– Spices and seasonings
» Give characteristic flavor
– Phosphates
» Increase water-binding and improve yield

35. • Smoking
– Along with heating, is integral to curing process
– Lowers microbial population due to heat and the addition of chemicals during the
process have bacteriostatic action
• Functions of modern commercial meat curing and/or smoking (Romans et al., 2001)
– Food safety
– Refrigerated shelf life extension
– Flavor development
– Color development (internal and external)
3. Microbial Methods of Preservation
• Competition
– Competition for survival among mist population of microorganisms
• Fermentation
– Strong preservative action and produces rich flavors
– Two types of fermented meat products:
» Dry
» Semi-dry
• What factors should be considered when selecting a meat preservation method?
– Factors to consider when selecting a preservation method:
• The method should be practical and usable
• The method should not make the product unpalatable or worsen its appearance
• The method must not in any way harm consumers

36. What is Curing?
• Curing is addition of salt, sugar, and nitrite
or nitrate to meats for purpose of
preservation, flavor enhancement, or
color development.
• Today curing is performed more for flavor
development than for preservation

37. Other functions of curing
– Shelf life extension
– Development of unique properties
– Resistance to rapid deterioration
– Controlling microbial growth.

39. Curing Reaction
• Basic Cure Reaction (1st
Step)
Deoxymyoglobin + Nitric Oxide = Nitric Oxide Myoglobin
(purplish red) (red)
• Nitric Oxide is generated during curing sequence
NaNO3NaNO2 HONO  NO
Nitrate Nitrite Nitrous Acid Nitric Oxide
• Nitric Oxide myoglobin in unstable
– Color must be “fixed” by heating to 140 degrees.

40. Curing Reaction
• Fixation Reaction
Nitric oxide myoglobin +Heat = Nitrosylhemochromagen
(red) (cured pink)
– Nitrosylhemochromagen is responsible for stable cured-pink color.
– Very Heat Stable- pink color doesn’t change with further cooking
– Only occurs with the addition of heat
• Overall Reaction
Myoglobin + NO Nitric Oxide Myoglobin Nitrosylhemochromagen
(purplish red) (red) HEAT (cured pink)

41. Curing Ingredients
• Salt (NaCl)
– Contributes flavor
– Preservative effect
– Controls microbial growth (doesn’t kill bacteria)
– Osmosis (enhances transport of nitrate, nitrite, and sugar)
– Can be in granular or rock forms.

42. Curing Ingredients
• Sugar (C12H22O11)
– Contributes flavor
– Counteracts salt
– Provides source of energy for nitrate converting bacteria
– Lowers the acidity of the cure
– Can be added in the form of:
• Sucrose (table sugar/brown sugar)
• Dextrose (refined corn sugar)
• Corn syrup solids
– Commercial cures use corn syrup solids
• Cheaper
• May require more to get same flavor

43. Curing Ingredients
• Nitrite (NaNO2) or Nitrate (NaNO3)
– Contributes flavor
– Prevents warmed-over flavor (WOF) in reheated products
– Retards development of rancidity during storage
– Prevents growth of C. boltulinum in canned products
– Bacteriostatic
– Contributes cured-pink color to the product.

44. Nitrites & Nitrates
• Usually come in the form of potassium or sodium nitrites or
nitrates.
• FSIS allows use of nitrate (NaNO3 or KNO3) ONLY in dry
cured meats or dry sausage.
• FSIS (Food Safety and Inspection Service) permits use of
Nitrites (NaNO2 or KNO2) in bacon
– Ingoing nitrite level cannot exceed 120 ppm
• Must be accompanied by 550ppm sodium ascorbate or
sodium erythorbate
– Residual nitrite must not exceed 40 ppm

45. Curing Adjuncts
• Proper color development is a function of time
• Ascorbic Acid, Sodium Ascorbate and Sodium Erythorbate speed
color development
• Ascorbates reduce Metmyoglobin to Myoglobin
– Metmyoglobin is unable to combine with NO, while Myoglobin
can
• Ascorbates speed reduction of HONO to NO
– Greater quantities of NO available for production
• Treatment of cured cuts with 5-10% Ascorbic Acid
– Effective in reducing fading of cured color in displays

46. Alkaline Phosphates
• Usually Sodium Tripolyphosphate
• Added to decrease shrink during curing &
smoking
• Cannot exceed 0.5%
• Increase water holding capacity (WHC) of
muscle proteins

47. Water
• Water is “curing ingredient” when doing Cover Pickle
Curing (Brine) or Injection Curing
• Disperses cure throughout meat
• Use of water reduces cost of products
– Products with more water are cheaper

48. Application of Curing Ingredients
• Dry Curing
– Use of salt or salt plus nitrite or nitrate
– Dry Sugar Curing
• Uses Sugar to overcome harshness of salt flavor
– Both methods involve rubbing cure mixture over surface
– Penetration of NaCl occurs through osmosis
– Bone Sour (souring around bones) occurs in hams
• Lack of rapid-enough salt penetration to interior
– High levels of shrinking

49. Application of Curing Ingredients
• Curing With Liquid
– Can either be Cover Pickle (placing meat in brine) or Sweet
Pickle (sugar added to brine)
– Penetration of cure occurs via osmosis
– More uniform distribution of cure
– Can Result in Bone Sour
– Can result in yeast growth

50. Injection Curing
– Three forms of injection curing
1. Stitch or spray pumping
– Cure directly injected into meat with
needles
1. Artery Pumping
– Accomplishes best possible distribution of
cure
– Cure dispersed via capillaries

51. 3. Multi-needle Machine Injection
– Most commercial facilities use
– Rapid penetration of cure into
meat (reduce spoilage)
– Less spoilage and shrinkage
– Not conducive to development
of typical flavor, aroma, and
texture

52. The History of Sausage
• The word sausage comes from the Latin word
“salus” meaning “salted”
• The earliest sausages were created in ancient
Rome and Greece
• Roman soldiers traveled with sausages and
introduced sausages to other parts of Europe
• By the Middle Ages, regional forms of sausage
began to evolve into definite and unique
forms all over Europe

53. Sausages
Sausage: A mixture of ground meat, usually pork,
and seasonings stuffed into a casing.
• The term sausage may also be used for the meat
mixture itself without the casing.
• Reduced to its simplest form, sausage meat may be
nothing more than ground pork seasoned with salt.
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54. Sausages
Sausages can be classified into three basic
groups:
• Fresh sausages
• Contains no nitrates or nitrites by USDA definition.
• Cured sausages
• Contains nitrites or nitrates of sodium.
• Smoked sausages
• May be hot smoked (and therefore cooked) or cold smoked.
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Categories of Sausages

55. Sausages
The basic ingredients of sausage meat are the
following:
• Lean pork
• Pork fat, preferably hard fatback ground with the meat.
• Salt
• Spices, herbs, and other seasonings and flavorings.
• In the case of cured sausage, curing mixes containing
nitrites or nitrates are added to the above list.
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Basic Sausage Ingredients

56. Sausages
The Meat
• Pork is the most commonly used meat in sausage-making.
• Other meats or mixtures of meat may be used:
• Beef
• Veal
• Lamb
• Chicken
• Turkey
Certified Pork: Certified to be free of trichinosis.
• Used for sausages meant to be air-dried and eaten uncooked.
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• Duck
• Liver
• Rabbit
• Venison
Basic Sausage Ingredients

57. Sausages
The Fat
• It is an important ingredient.
• Our impression of juiciness in any cooked meat is largely due
to the meat’s fat content.
• In most traditional sausages, fat makes up 25 to 50 percent of
the total weight.
• Proportions of fat to lean:
• 3 parts lean plus 1 part fat (the leanest sausages).
• 1 part lean plus 1 part fat (rich, fatty sausages).
• Hard fatback is preferred over other fats for pork sausage.
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Basic Sausage Ingredients

58. Sausages
Casings
• Natural casings are made from the intestines of
meat animals.
• Natural casings are often sold packed in salt.
• Due to the preservative effect of the salt, the casings keep
indefinitely as long as they are refrigerated.
• Natural casings are easy to use if they are handled
correctly.
• Before being stuffed, they must be untangled, rinsed, flushed,
and examined for holes.
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Basic Sausage Ingredients

59. Sausages
Casings
• Sheep casings are the smallest.
• Range from ¾ in. (18 mm) to more than 1 in. (25 mm) in
diameter.
• They are used for breakfast links, frankfurters, and similar
sausages.
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Basic Sausage Ingredients

60. Sausages
Casings
• Hog casings
• Medium-sized.
• About 1 to 1½ in. (3 to 4 cm) in diameter.
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Basic Sausage Ingredients

61. Sausages
Casings
• Beef casings range in size from:
• Beef Round: About 1¾ in. (45 mm) in diameter
• Beef Middles: 2½ in. (63 mm) in diameter
• Beef Bung: More than 4 in. (100 mm) in diameter.
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Basic Sausage Ingredients

62. Sausages
Before grinding meat, it is important to be sure of
the following two points:
• The equipment must be clean and sanitary.
• Make sure there is no trace of food from previous jobs hiding in
the many nooks and crannies of the grinder, blades, and dies.
• The equipment must be cold in order to avoid warming
the meat.
• Refrigerate the grinder parts or set them in ice water before
use.
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Equipment

63. Sausages
The following cooking methods are most often
used for sausages:
 Simmering
 Pan-frying
 Braising
 Broiling and grilling
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Cooking Sausages

64. Drying
• Removal of water from fish (to reduce water
activity) to extend shelf life
• Requires input of heat (evaporate water)
– Sun, wind, flame, electrical etc.
• Requires removal of water in the form of vapor
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65. Salting
• Salting - traditional method
• Reduces water activity (aw) to retard microbial
spoilage and chemical reactions
• Salt penetrates into the muscle and binds the
water.
• At 6-10% in the meat will spoilage
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66. Smoking
Old preservation method. In developed countries, used for flavor
and color
Smoking temperature
1. Cold smoking
Room temperature (<90 F)
Not cooked
Perishable product
2. Hot smoking
Temperature (>150 F)
Cooked
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67. Liquid smoke
Smoke is absorbed by a liquid, and
concentrated.
Rapid, uniform, but different than “real”
smoke
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68. Smoke generation
Wood:
Sawdust or wood chips heated to form smoke, but
no flames.
Hardwood. Oak, mahogany, teak, hickory,
redwood, cedar, pitch-pine.
Resinous wood: bitter taste.
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69. Vapors
Antioxidants: high boiling phenols
Smoldering fire is better
Bactericidal: formaldehyde, acetic acid,
creosote.
Also heat, drying, salt.
Reduces bacteria, fungi, viruses
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70. Safety
Smoke has carcinogenic substances.
Polycyclic aromatic hydrocarbons (PAH):
Benz(o)pyrene. Thermally generated.
1-60 ppm in food.
Lower smoke generation T is better.
Use liquid smoke, or electrostatic filters.
Nitrosamines
Nitrous oxide in smoke: very low concentrations in
food
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71. Smoke generation
Temperature:
High T: cooking, rapid drying, reaction between
smoke and food.
Dry surface: less smoke absorption.
Optimum smoke generation = (550°F).
At higher T more smoke, but less active
components.
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72. Relative humidity
Surface moisture is needed for smoke
absorption.
60 % RH optimum
Skin-side absorbs less smoke.
Too high RH: slow drying.
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73. Smoke velocity
Faster smoke= better penetration
Absorbed smoke near surface is replenished.
Stagnant film on surface decreased, and diffusion
path shortened.
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74. Caning
Caning is a method of packaging of food in a hermitically
scalded container and obtaining commercial sterility by
using high heat treatment.
Steps of Caning:
1.Filling the meat into the can.
2.Additions of intergradient‘s
3.Exhausting /vacuumization of the can.
4.Sealing the can
5.Heating or Retorting:
6.Rapid cooling
7.Labelling, packagings and storage.