Transcript Meat - vandermarkj

Meat
Meat
Meat is an important food
commodity which provides
nutrients essential for health.
A variety of different textures,
colours and flavours of meat are
available for you to choose.
This unit contains an overview of
the origin, structure and
composition of different types of
meat.
Types of meat
Meat is the flesh of animals and birds that is eaten by humans.
Red meat includes flesh from
•
Cattle (beef)
•
Sheep (lamb)
White meat encompasses flesh from
•
Pigs (pork)
•
Calves (veal)
•
Poultry (chicken, turkey, duck)
Game meat is dark meat that may come from
•
Rabbits
•
Kangaroo
•
Crocodiles
•
Deer
•
Wild birds
The structure of meat
Animal flesh consists of muscle tissue or fibres, connective tissue
and fatty (adipose) tissue.
Lean meat is the muscle tissue of animals.
Meats are composed of a combination of
• water 75%
• proteins 20% (actin and myosin in muscle fibres) (elastin and collagen in connective tissue).
• vitamins and minerals 5%
• Fat 5-40%
What’s the connection?
Meat muscle is made up of bundles of
long muscle fibres held together by
creamy white connective tissue.
Tendons join the muscle (made up of
bundles of muscle fibres, surrounded
by connective tissue and fatty tissue)
to the bones of
animals.
Component 1: Muscle
Individual muscle fibres are made up of cells which contain the
proteins actin and myosin.
In live animals, actin and myosin work together to make the
muscle contract and relax.
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Muscle fibres
Muscle fibres are very small – and can only be
seen under a microscope. The length of muscle
fibres varies.
Fine muscle fibres
These tend to come from the muscles of young
animals, or in older animals from the muscles
which do least work.
They contain little collagen and are tender even
when cooking times short, e.g. grilling.
Thick muscle fibres
These tend to be from older animals and also muscles which do the
most ‘work’ – such as neck and shin.
They have more connective tissue to prevent muscle damage.
This type of meat is tougher and needs long, slow cooking with
moisture to make it tender, e.g. casserole.
Component 2: Connective Tissue
Connective tissue is made up of two proteins called collagen
and elastin.
Collagen
The connective tissue in and around the muscle fibres and
tendons is mostly collagen. When meat is cooked, the collagen
becomes soft and soluble, and forms gelatine.
Elastin (gristle)
This is much more elastic connective
tissue.
It is yellow in colour and remains tough,
even when cooked. The ligaments which
join two bones together are mostly made
up of elastin.
Component 3: Fat
visible fat
Visible fat
Fat is found in meat underneath the skin
(subcutaneous fat) and between the muscles
(intermuscular fat) and is a creamy-white
colour.
Visible fat (called suet) is also found around
the animal’s organs, such as the kidneys.
Invisible Fat
A small amount of fat is also found in connective tissue surrounding the
bundles of muscle fibres. This is usually not obvious to the eye, so it is
known as invisible fat. Sometimes these lines of fat can be seen and give
meat a ‘marbled’ look.
The colour of meat
The colour of meat is largely due to the red protein
called myoglobin and some haemoglobin (blood) left in
the muscle. Some muscles contain more of these red
pigments than others.
Colour differences can be due to age and exercise, but
are mainly due to the metabolism of the species and
the function of the particular muscle.
Meat from muscles which have been used a lot and are
from older animals is usually a darker colour. For
example, chicken breast is much whiter in colour than
the leg or wing. Also chicken is much lighter than duck
due to the fact that they are not a bird of flight; whereas
duck is a darker meat due to the fact that it moves
more.
The colour of meat
During the time meat is stored the colour changes to a darker
brown-red because of the formation of metmyoglobin.
When meat is cut and exposed to oxygen in the air, it takes about
twenty minutes for myoglobin to change to oxymyoglobin, which is
brighter red in colour.
After some time, the meat becomes a browner colour again as
metmyoglobin is formed.
These colour changes do not make any difference to the taste or
texture.
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Tenderness of Meats
Overall , natural meat tenderness is due to factors such as the cut, age, and
fat content.
Cut.
The toughest cuts of meat come from the hardest working muscles that do more
exercise and have greater amount of connective tissue e.g neck, shoulder, chest
(beef, lamb, pork) wings, legs (poultry). Parts of the animal which do greater
exercise are also darker due to increased blood flow. Tender cuts are from the
parts that are not worked as hard and have less connective tissue e.g the beef
rump, sirloin and chicken breast.
Age
The more younger the animal, the more tender it is as the muscle fibres thicken as
the animal ages. Aging also means the animal exercises more causing a greater
development of connective tissue.
Fat content
Increased fat throughout the meat (marbling) can increase tenderness as the fat
melts during cooking to give increased moisture and juiciness. However as an
animal gets older, the visible fat increases which provides toughness.
Tenderness of Meats
Overall , natural meat tenderness is due to factors such as the cut, age, and
fat content.
Meats can also be treated to make them more tender.
•Enzymes are sometimes injected to the animal before slaughter or used in many
‘meat tenderiser’ products. The enzymes used include:
Papain- Papaya
Ficin- figs
Bromelain- Pineapple.
•Mechanical methods such as chopping, grinding, pounding etc
•Marinades containing acids chemically break the meat fibers.
•Preparation temperatures and times also have an influence on tenderness.
Choice of cut and method?
Tender cuts suit quick dry cooking as they have little fat
and connective tissue. e.g. Grilling, deep frying, pan
frying,
Tougher cuts suit longer cooking times as the connective
tissue needs time to break down. They can be cooked
dry (roasting) but are mostly suited to slow, wet cooking
methods. e.g. stewing, braising.
Justify with reasons what cut you would choose for…
a chicken casserole?
a steak sandwich?
a beef bourguignon?
A chicken parmigana ?
Changes that occur to the properties on
cooking meat
Texture
• Protein solidifies and becomes firm (coagulates). If overcooked
the protein shrinks and releases water leaving a dry meat.
• Collagen denatures and converts to gelatin over long times
• Meat goes from soft and mushy to firm, moist and easy to bite
Color
• Surface browning is due to the maillard reaction.
• Myoglobin pigment denatures and changes colour from red to
brown.
Flavor
• Cooking intensifies flavor and enhances aroma. Dry heat
develops best flavor due to surface browning in maillard reaction.
Nutritive value
• No loss of protein
• Some loss of B-vitamins
Why is it important to cook meat?
Safe to eat
• Meat is a high protein and high water food, making it a very high
risk for bacteria and food poisoning. Cooking meat above 70
degrees destroys bacteria.
More palatable
• Easier to chew as cooking changes texture.
Develop flavours
• Cooking intensifies flavor and enhances aroma. Intense heat
develops flavoured crust in maillard reaction.
Seafood
The three main types of seafood can be classified as
White fish
•less 5% fat
•delicate flesh
•tropical waters
•whiting, flathead, perch, john dory,
Oily fish
•between 10-25% fat
•darker flesh colour
•salmon, sardines, tuna,
•good source of omega-3 oils
Shellfish
•have an outer shell
•not as easily digested as fish
•two types
• Crustaceans – have a hard outer shell that turns orange when cooked.
Example: prawns, crayfish, crab
• Molluscs – have a shell that opens when cooked. Example: oysters,
mussels, clams, scallops
Seafood
Nutritional benefits (chemical properties)
• Contains complete protein (all essential amino acids)
• Fat in fish and seafood is good a source of Omega-3 oil - assists in
reducing heart disease
• B group vitamins
• A and D vitamins (oily fish only)
• Minerals
Phosphorus
Calcium
Iodine
Fluorine (salt water only)
Fish
Properties of fish
• 70 % water
• 20% protein
• Muscles of fish are arranged in layers of short fibres surrounded by
very thin sheets of delicate connective tissue.
• Very little amount of connective tissue. Only 3% compared with
meat having 15% of body weight.
• Fat in fish is good a source of Omega-3 oil - assists in reducing
heart disease
• In its raw state, fish is translucent, firm to touch and juices are clear
and watery.
• Fish when cooked becomes opaque, the flakes begin to separate
and the juices are milky white.
EXAM QUESTIONS
1.
The tenderness of meat is influenced by a number od factors including the age of the
animal, the muscle from which the meat comes from, the activity levels of the animal, the
use of acid marinades, preparation techniques and fat content.
Select 3 of the factors above and describe how each one contributes to the overall
tenderness when it is cooked.
9 marks
2.
There are a number of changes that occur to the properties of meat when it is cooked.
Describe these changes in detail.
6 marks
1.
Meat is usually cooked before it is eaten. Provide a detailed explanation of why it is
important to cook meat prior to consumption.
3 marks
2.
Japan has one of the highest life expectancies of any population in the world. This has
been attributed to the fact that Japanese people eat a large amount of deep sea fish such
as Salmon.
Explain why this high consumption of fish may contribute to a greater life expectancy
and explain why fish is a healthy choice.
2 marks