HNF 101 Meat Part 1

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Meat refers to the what of the animal?

flesh or edible part of the striated muscle

Meat includes?

organs, glands

Two categories of meat?

Red meat and white meat

Red meat refers to?

Anything except fish and poultry

beef refers to?

meat of cattle

what is a steer?

castrated male cattle before dev. of secondary sex characs.

heifer

female cattle no born calf

cow

female cattle born calf

stag

male desexed after maturity

bull

uncastrated male cattle

calf

3-8 months old

too old for veal, to young for beef

veal

calf slaughtered at 9 months

what are the meat of sheep?

lamb - younger 14 months

mutton - older 14 months

meat is the major source of?

protein, B vitamins, iron and phosphorus, UFA

pork exhibits a large amount of?

thiamin (B1)

meat liver is?

concentrated source of Vit. A

negative nutritional aspect of meat?

saturated fat and cholesterol content

what is the overall composition of meat?

muscular/lean tissue

connective tissue

fatty/adipose tissue

bone

water

muscular/lean tissue consists of?

one or two muscles

muscle tissues are made of?

muscle fiber bundles

muscle tissue has less amount of?

connective tissue and fat

protein content of muscle tissue?

18%

muscle fibers are?

basic structural units that make up the fasciculi

what is fasciculi?

muscle bundle

each muscle fiber is filled with?

sarcoplasm

what surrounds the sarcoplasm?

sarcolemma - outer membrane

what does the sarcoplasm contain?

• pigments, vitamins, enzymes

• muscle fibrils to act as contractile components

what are the three connective tissues in the muscle/lean tissue?

• perimysium

• endomysium

• epimysium

function of perimysium?

envelopes individual muscle bundle

function of endomysium?

delicate tissue found between muscle fibers

function of epimysium?

envelopes entire muscles

what are muscle fibrils?

muscle fibers that contain muscle proteins

muscle fibrils are separated into?

sarcomeres

what are the muscle proteins?

• myosin (thick filaments)

• actin (thin “)

• tropomyosin

what is tropomyosin?

myosin is the principal myofibrillar protein

what is actomyosin

formed during muscle contraction

how is actomyosin formed?

union of actin and myosin

how is formation and degradation of actomyosin catalyzed?

• ATP

• Ca

• Mg

what are connective tissues part of?

ligaments and tendons

connective tissues act as?

glue holding muscle fibers into bundles

what are the different connective tissue proteins?

• collagen

• elastin

• reticulin

• ground substance

what is the most important connective tissue muscle protein category?

collagen

characteristics of collagen?

• white, tough, fibrous protein

• arranged in parallel fashion

• located between muscles

function of collagen?

• provide support to muscles

• prevent muscles from over-stretching

collagen determines?

toughness of meat

what areas are high in collagen?

muscles used for movement

• neck

• legs

what happens when muscle is exercised (re: collagen)

fiber expands and its connective tissues thicken making it larger, redder, tougher, and more flavorful.

when collagen is exposed to hot water/cooked?

disintegrates/converted to gelatin

characteristics of elastin?

• yellow

• found in deposits outside muscles

• rubbery

elastin is necessary for what tissues?

tissues in

• neck

• abdominal/intestinal wall

• arterial system

when cooked, elastin?

does not tenderize

why is elastin rubbery?

due to

• desmocine

• isodesmocine

characteristics of reticulin?

• made of very small fibers of connective tissues

• form interlaces around muscle cells

reticulin is associated with?

myristic acid

what is ground substance?

undifferentiated matrix of plasma proteins and glycoproteins

fibrous molecules of what proteins are bound to ground substance?

• collegen

• elastin

where are adipose/fatty tissues found?

• around/between muscles

• in connective tissue

what are the different fatty tissues?

• cover fat

• intramuscular fat

where is cover fat found?

outside of meat

function of cover fat?

retaining moisture of meats

what are the fatty acids that are mainly saturated found in the triglycerides in the fat depots

• oleic

• palmitic

• stearic

what are the lipid and lipid-related compounds?

• cholesterol

• glycolipids

• phospholipids

• sphingomyelin

amount of fat depends on?

• age

• feed

• amount of exercise

• species

large amount of fat is found in what animals?

• older

• well-fed

• limited exercise

what animal accumulates more fat readily than other animals?

pig

bone determines what?

age of animals

young animals is characterized by what bone?

• soft backbone

• reddish tinge

mature animals is characterized by what bone?

flinty and white bones

pigments are responsible for?

meat color

what are the different pigments in meat?

• myoglobin

• hemoglobin

• oxymyoglobin

• metmyoglobin

• denatured globin hemochrome

• carboxymyoglobin

• nitrosomyoglobin

what is myoglobin?

• accounts for 80% of meat pigment

• receives oxygen from blood and stores it in the muscle

what is hemoglobin?

• accounts for 20% of meat pigment

• transports oxygen throughout body

• present in the bloodstream

what is oxymyoglobin?

• cherry red

• due to reaction of myoglobin with oxygen

• medium-rare color

what is metmyoglobin?

• brownish red

• due to reduction of oxymyoglobin

• exposure of myoglobin to fluorescent or incandescent light

what is carboxymyoglobin

• due to bbq grilling

• myoglobin exposed to carbon monoxide

what is denatured globin hemochrome?

• cooked meat

• grey-brown or well-done color

what is nitrosomyoglobin?

• pink red color of cured meat

• myoglobin reacts with nitrate

when does muscle convert to meat?

as soon as

• after the animal has been bled

• oxygen in muscle is rapidly exhausted

how is early meat spoilage prevented?

all blood is pumped out

method of pumping out blood to prevent early meat spoilage?

stunning via stunning gun before killing

• cardiac activity and pumping out of blood from the vessel continues

what are the 3 stages of meat changes?

1. immediately after death

2. onset of rigor morties

3. post rigor stage

what meat change happens immediately after death?

• muscle is pliant and soft

• most tender stage

• should not be frozen

why should meat not be frozen immediately after slaughter?

thaw rigor

what is thaw rigor?

excessive muscle shortening and drips upon thawing

what is cold shortening?

sever muscle contraction in carcasses due to quick and severe chilling after slaughter

what meat change happens in onset of rigor mortis?

• 12-24 hours after slaughter

• decrease in pH

• muscle is rigid, inflexible, tough

• depletion of ATP → contraction of muscles

why does rigor mortis happen?

decrease in pH of meat

why are the muscles temporarily rigid, inflexible, and tough?

muscles are contracted due to shortening due to ATP

what meat change happens post rigor stage?

• meat gradually tenderizes

• desirable flavor develops

how is the meat gradually tenderized post rigor stage?

aging

what is aging?

• meat is held at a temperature above freezing

• muscle structure weakens due to loss of biological regulation of proteinases

how is the carcass of the slaughtered animal cut?

• split longitudinally down center into right and left sides

• horizontally into fore and hind quarters

• wholesale or primal cuts

what is meat grading?

classification accdg to (..of carcass):

• quality

• conformation

• finish

quality in meat grading refers to what quality of meat?

• tenderness

• juiciness

• palatability

tenderness refers to?

universally accepted meat quality

what are the factors affecting meat tenderness?

1. amount and type of connective tissues

2. quality and distribution of muscle fibers

3. amount and distribution of fat

4. aging

what does amount and type of connective tissue entail?

more elastin = less tender

less elastin is found in what animals?

• younger animals

• chicken than pork

• less exercised

• females

• castrated animals

what does Quality and distribution of muscle fibers entail?

dense, coarse, parallel than circumstantial arrangement of muscles = tougher

what does Amount and distribution of fat entail?

marbled meat = tenderer