Download 9 Quality of fresh meat

Fresh Meat Quality
Aixa Rivera, MS
Extension Beef Cattle Specialist
Department of Animal Industry
UPR - RUM - CCA
Production cycle
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Meat is define as:
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animal tissues that are
suitable for use as
food.
Includes processed or
manufactured products
that might be prepared
from these tissues.
It also includes:
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Liver
Heart
Intestines
Stomach
Kidneys
Other
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Fresh Meat:
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Meat that has undergone
the chemical and
physical changes that
follow slaughter and has
only been minimally
processed,
Such as
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fabrication into retail
cuts,
de-boning
Grinding/ cubing
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Processed meat
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Meat whose fresh
properties have
been modified by
one or various
processes:
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Adding of spices or
curative salts,
Color alteration
Thermal treatment.
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Quality
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Group of properties or
attributes that gives meat
products the necessary
characteristics to be
accepted.
Principally :
‰ Nutritional quality –
objective
‰ Acceptance or
comsumtion quality –
subjective
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Sensory characteristics
Safety
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Risk factors:
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Handling during the muscle
to meat period:
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Nutrition
Transportation
Stunning
Bleeding
Evisceration
Washing
Storing
De-boning
Packing
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Handling of fresh meat:
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Cutting/ retail cuts
Grinding/ cubing
Further process
Packing
Storage
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Characteristics of
fresh meat: Quality
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Characteristics of fresh meat:
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Determines market use,
Attractive for the consumer
or buyer
Determines its use for
further processing
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Most important attributes of fresh meat:
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Water Holding Capacity (WHC)
Color
Structure, firmness and texture.
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Water Holding Capacity (WHC):
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The meats ability (myofibril
protein) of retaining its
water or added water,
during the application of
external forces such as
cutting, grinding or
pressing.
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Importance due to its
influence on:
„ Color, texture and
firmness of raw meat
„ Palatability
characteristics
„ Juiciness and
tenderness of cooked
meat.
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Water
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Principal component of meat, estimated close
to 70 – 75% (muscle is 65 to 85 %)
Most variable component
Most of the meats water is in the free state.
Affects juiciness.
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Color
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The color sensation varies with the observers vision,
the quality and intensity of the light and the chemical
and physical properties.
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Color is produced by pigments:
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Components of the cell or tissue that produces
color. (proteins)
Absorbs some wave lengths and reflects others.
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Affected by light conditions in place.
Texture and structure also affects:
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Compact and firm – dark
Soft and flaccid – pale
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Most important pigments:
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Myoglobin
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Principal pigment of the muscle
80 – 90% of total muscular pigments (heme-pigment)
Hemoglobin
pigment in red blood cells
‰ 20-30 % present
‰ Serves as oxygen transport from the lungs to muscle.
In a well bled animal, 80-90 % of the color is due to Myoglobine,
because it is the most abundant.
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Color depends on:
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Type of muscular fiber:
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White – less concentration of myoglobine
Red – more concentration of myoglobine
Meat has a combination of these different types
of fiber.
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The color intensity is affected by the amount of
myoglobine.
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Age
Specie
Sexual category
Muscle position and function
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Age
Age
Myoglobine
Veal
2mg/g
(1 – 3)
Calf
4mg/g
(4 –6)
Heifer/bullock
Adult
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8mg/g
(6 – 10)
18mg/g
(16 – 20)
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Difference among species:
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Species
Color
Myoglobine
Pork
Pink/ gray
2mg/g
1-3
Lamb
Brick Red
6mg/g
4–8
Beef
Bright Red
8mg/g
4 – 10
Tuna
White/ gray
0.5 – 1 mg/g
Chicken
Light beige
1 - 2 mg/g
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Localization and function of the muscle:
Localization / Function
Muscle name
Myoglobine
Locomotion
Extensor carpi radialis
12mg/g
Support
Longissimus dorsi
6mg/g
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Localization / Function
Myoglobine
Leg
1.75 – 2.0mg/g
Heart
6mg/g
Gizzard
19.6 – 26.5mg/g
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Color is affected by pre and post-management:
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Stress
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Fight or flight
Conditions that can be produced:
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Pale Soft Exudative
Dark Firm Dry
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Pale Soft Exudative:
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Common in Pork – Porcine Stress Syndrome – 5 – 10%
Results in pale meat, lots of water loss (low WHC) and loss of
firmness.
May cause low yield % in process meats, increases loses
while cooking, reduction of juices.
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Dark Firm Dry
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More common in beef (3%)
Cause by excess of ante-mortem physical activity
Results in dark color meat, increase of WHC, very firm.
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Bacterial activity causes changes in
color:
Pigment
Catalysis
New pigment
Color
Oxymyoglobine
Oxidation +
bacteria
Metmyoglobine (-OH)
Brown
Metmyoglobine
Bacteria
produces H2O2
Coleglobine (-H2O2)
Green
Metmyoglobine
Bacteria
produces H2S
Sulfmyoglobine (-SH)
Green
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Color changes during cooking:
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Changes in color due to:
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increase of internal To.
denaturalization of the
pigments
When meat is cooked all the
oxymyoglobine and
myoglobine are changed to
metmyoglobine.
Once all reaction have been
completed the protein is
denaturalized.
Surfaces changes:
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Maillard Browning – carbonylamine browning (sugar amine
browning)
Surface Dehydration –
crystallization
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Structure, firmness and texture:
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These properties are very
difficult to measure objectively
and are measured by the
consumer through the use of
his senses.
Some factors that affect these
properties are:
‰ Grade of firmness,
‰ Intramuscular fat content.
‰ Connective tissue content.
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Firmness grade :
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During chilling the carcass has developed firmness:
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Loss of extensibility
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solidification of intra and inter muscular fat
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High quantity of trapped water
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Tissues of great firmness:
sensation of a sticky and dry texture.
Non tender meats:
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Granulose structure
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Humid (poor WHC).
Firm cuts with well defined muscles are preferred.
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Fat, meat and connective tissue:
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Subcutaneous, Intermuscular,
Intramuscular (marbling), Offal
Solidification of fats
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Helps maintain the cuts
uniform and with their
characteristic form.
Locomotion muscles:
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Great quantity of connective
tissue.
Texture tend to be open
coarse, less tender.
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Questions??
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