Lecture 13 Flashcards
What are the overall consumption trends of meat consumption?
Beef decreasing
Chicken increasing
Offal remaining low
What is meat a good source of and an excellent source of?
Good:
- thiamin
- riboflavin
- niacin
Excellent:
- Fe
- Zn
- Se
- P
What is the breakdown of the composition of meat?
75% water
20% protein
5% Fat, Cholesterol and minerals
What does the composition of the meat depend on?
Cut of meat
Connective tissue
what is lean meat a good source of?
- thiamin
- riboflavin
- niacin
- tryptophan (precursor to niacin)
What is the composition and structure of meat?
Muscle Connective tissue Fatty/ adipose tissue Bone Pigments
What is a muscle composed of?
Muscle>Muscle Fibres> Myofibrils
-each myofibril is surrounded by a sarcoplasm and each fibre is surrounded by a sarcolemma
What are the tings found within a myofibril?
Proteins that form thick (myosin) and thin (actin) filaments
What do thin and thick myofilameents do?
Slide together when muscle contracts forming actomyosin
-cross-bridge is formed when they slide together, shortening the muscle
What is connective tissue?
Makes up tendons and ligaments
Needed to bind muscle cells together
What are the 3 kinds of connective tissue?
Collagen: white, non-flexible/elastic as elastin
Elastin: yellow and elastic
Reticulin: very small fibres, forms delicate network around muscle cells
What happens when connective tissue is hydrolyzed?
produces gelatin
Where do you see more connective tissue?
Tends to develop more extensivley in animals that move around more (cattle)
Which cuts of meat have more connective tissue?
Less tender cuts have more connective tissue and are less tender
What does fatty tissue vary with?
Different animals
What kind of fat do beef and mutton have?
Hard more brittle fat
Contains higher % of saturated fatty acids
What is a characteristic of softer fats?
Higher percent of unsaturated fatty acids
Why might fat be yellow in colour?
Animal feed
Animal is older
-Carotenoid pigments accumulate overtime
What are the 3 kinds of fatty tissue?
Intramuscular
Intermuscular
Subcutaneous
What is intramuscular fat?
Also called marbling
Associated with juiciness, flavour and tenderness
What is Intermuscular fat?
Between individual muscles
Seams of fat
What is Subcutaneous fat?
Found under skin
May be trimmed before sale to consumer
What is the purpose of bones?
To help identify retail cuts of meat
-back or chine bone
What are the 2 categories of bones?
Young animal: bone is red and less hard
Mature animal: bone is white and hard
What does the pigment of meat varry with?
Age of animal
-darker in older
Type of meat
-pork lighter than beef
Why colour does myoglobin produce?
purple red
-contributes little colour to the meat cause most of the blood has already been drained off
What are the 3 forms of myoglobin?
Oxymyoglobin
- birght cherry red
- formed in presence of O2
Deoxymyoglobin
- purple red
- formed with little O2
Metmyoglobin
- brown
- holding onto water
What is myoglobin affected by?
Presence of O2 and light exposure
- Not necessarily an indication of spoilage
- Temperature is best indicator of doneness not colour
What things can affect colour of meat?
pH, meat source packaging, freezing, fat content other added ingredients
What are the classifications of beef?
Steer Heifer Cow Stag Bull
What is a steer?
Male castrated when young
-preferred for retail
What is a heifer?
Young female that has not yet given birth to a calf
-preferred for retail
What is a cow?
Female that has given birth to a calf
What is a stag?
Male castrated after maturity
What is a bull?
Mature male that has not been castrated
-used in processed meats
What is veal?
From immature cattle of at least 3 weeks and less than 20 weeks of age
What are the 3 classifications of lamb
Lamb: less than 12 months
Yearling mutton: about 12months
Mutton: passed lamb stage
What is rigorous mortis?
Stiffening of carcass occurs due to metabolic changes
- the accumulation of lactic acid in the muscles
- loss of ATP
What are the factors that impact rigor mortis ?
Temp
Species of animal
Age
Activity before slaughter
How long does rigor mortis last in beef?
24-48 hours
What happens when there is low glycogen in the muscle ?
It means the animal was active befroe slaughter, so therefore therer is less lactic acid, pH would be higher and gives the meat an undesireable dark colour is produced
What is aging of meat?
Holding of meat after rigorous mortis is resolved
- beef 11-14 days
- lamb may be aged
What does again promote?
Increased tenderness
Improved flavour and juiciness
What are the 2 methods of aging?
Wet aging> aged “as is” under refrigeration
Dry aging> meat is packaged in a vacuum bag and held under refrigeration
-more expensive
What is tenderness the result of?
Breakdown of proteins in the myofibrils
What is case ready meat?
Packaged cent5rally and then delivered to retail stores
What is vacuum packaged?
Reduces O2
Purple red colour until opened
What is high O2 modified atmosphere?
Often sold on a tray covered with clear film, meat is bright red but will brown over time due to high O levels
What is low O2 modified atmosphere?
Use Carbon monoxide
-shelf life is usually longer compared to other methods, meat will remain a bright red colour for longer
What are the 2 governing regulation and standards that pertain to meat?
Criminal code of canada prohibits anyone from causing animals to suffer
CFIA verifies that meat and poultry leaving federally inspected establishments or being imported are safe
How do you break down the cuts of an animal?
Primal/wholesale cuts then retail cuts
- 1st division of the carcass
- 2nd divided into retail cute
How do butchers know where to cut?
Division of cuts is made in relation to bone and muscle structure
-shape and size of bones and muscle in retail cute act as a guide to identification
What is the IMPS?
provide standaddized meat cuts by number. Basically helps those purchasing meat for food service purchase the meat that they want and it clearly stated
What is involved in restructured meat?
Flaking, coarse grinding, dicing, chopping the meat
Ingredients added to promote bining
Meat formed into desired shape and size
What are ingredients the promote binding in restructured meat?
Salts,
phosphates
-basically used to solubilize the muscle proteins on the surface of the meat pieces. This helos witht the binding process
What are some examples of restructured meats?
deli meats,
chicken nuggets,
canadian style bacon
What are variety meats?
Sweetbreads (thymus gland) Heart Tongue Tripe Liver Kidney Oxtail
What is the difference between ground beef and hamburger?
Both are beef that is ground
Hamburger has fat added to it to increase the %fat
What happens to the ground meat as fat decreases?
Cooking yields increase with decreasing fat content
Tenderness and juiciness decrease as fat decreases
What is the max % fat that could be added to a hamburger?
30%
What bacteria is most commonly associated with ground beef?
Ecoli
-irradiated beef can help reduce the chances
How can you be money conscious when purchasing meat?
Economical cuts (chuck/round)
Cost per pound (AP) and cost per pounds (EP)
Is there a lot of fat that needs to be trimmed
Bone or not
What does the tenderness of the meat depend on?
Animal maturity Post mortem aging Muscle type Marbling Marinaing Mechanical tenderization Proper cooking methods Degree of doneness
What re the 2 ways of tenderizing meat?
Mechanical: grinding/cubing
Compounds: enzymes including proteinases
-papain, bromeliad (more effective on collagen)
when happens when you have a lot of tenderizing enzymes?
Results in a mushy meat texture
What effects the flavour of meat?
Cooking
feed
Time and temp
Reheating
How do you cure meats?
Na Nitrate
Sugar
Salt (produces pink pigment)
Seasonings
Where does cured meat get its pigments from?
Nitrate+myoglobin=nitrosylmyoglibin which when reacts with heat becomes nitric oxide hemochrome (pink pigment)
what are cured meat pigments reactive too?
Lighirng and may discolour in lighter display areas
are using nitrites/nitrates in meat safe?
- links to colon cancer
- Toxic when consumed in excessive amounts
- found naturally (celery)
What is the name of the cancer causing substance from nitrites/nitrates?
Notrocinines
-vitamin C and E counteract these
What temp should you cook ground beef, pork/beef too?
Ground: 68-70C
beef/pork/veal/lamb/roasts: 63C
What is not a reliable indicator of meat?
brown colour
what are dry meat prep methods?
Roasting Baking Broiling Pan broiling -best for tender cuts
where are moist meat prep methods?
Stewing
Cooking in water
Pressure cooking
-for less tender cuts
What is combination cooking?
Braising
-less tender cuts
What is the effect of heat on meat?
Fat melts Myoglobin denatured at 60C Decrease capacity of muscle to hold water Tenderness changes -Decreases 40-60C -Gradual increase above 60C
What is losses in meat?
Loss of weight and nutrients which increases with increasing internal temps
-greater thiamin lost in wet methods
Moist heat methods result in greater losses compared to dry heat
What is shrinkage in meat?
Begins at 50-60C due to the shortening of muscle fibres and coagulation of proteins
Increases with higher internal temps
What does grilling meat produce ?
Heterocuclic Amines HCAs
Polycyclic Aromatic Hydrocarbons PAH
Due to:
- cooking well done
- Burning
- Charred
Why are HCA and PAHs bad?
associated with a higher risk of cancer, typically not recommened to eat things that are burnt or charred
-But grilled fruits and veggies don’t produce the
How do you avoid HCA production?
Marinate,
trim fat,
flip meat
