獸醫(yī)公共衛(wèi)生學-07郵箱

Section

1The

morphosisandchemicalcomposing

of

meat(肉的形態(tài)結構和化學組成)College

of

Animal

Science,Dr

Aifang

Du2010-12-1321.

The

morphosis

of

meatThe

chemical

composingof

meatThe

edibleness

of

meatCollege

of

Animal

Science,Dr

Aifang

Du2010-12-1331.

The

morphosis

of

meat(1)Muscle①Composing

of

muscle:Integrate

muscle(完整的肌肉)Muscle

fiber(肌纖維)Myolin(肌纖維束)So

all

muscle

is

made

up

with

musclefibre

and

connective

tissue

(CT).The

quality of

meat rests

with

thethickness

of

the

muscle

fibre

and

thepercentage

of

CT.The

meat

is

more

delicious

with

thinnermuscle

fibre

or less

CT.The

factors

which

include

species,

breed,sex,

age

and

nutrition

condition

couldinfluence

on the

thickness

of

muscle

fibre..College

of

Animal

Science,Dr

Aifang

Du2010-12-137②The

color

of

meat(2)Connective

tissue

(CT)The

characteristic

of

protein

in

CT:The

more

CT,

the

less

delicious,

the

lessvalue

in

nutrition,

and

the

worse

quality.(3)Adipose

tissue(4)Bone2.

Chemical

composing

of

meat(肉的化學組成)Lean

meat(精肉)Moisture

wet72-80%Solid

matter(固體物)20-28%anicCompound(有機物)21-24%In

anicCompound(無機物)0.8-1.8%fat（脂類）21-24%others（其它）0.99-3.72%Protein（蛋白質）16.7-21.5%Chemical

composingofleanmeat(1)ProteinMyofibrillae

protein

(肌原纖維蛋白)including:Myosin---肌凝蛋白（肌球蛋白）Actin---肌纖蛋白（肌動蛋白）Myofibrilar

protein

ties

up

quality

andsome

specialities

(e.g.

tenderness)

of

meatand

is

essential

amino

acid

to

human

being.College

of

Animal

Science,Dr

Aifang

Du2010-12-1316(肌溶蛋白)肌紅蛋白)(2)

LipidTriglycerides(甘油三酯)is

main

material

of

Lipid,besides

there

are

littlephosphatide(磷脂),cholesterin(膽固醇),dissociativefattyacid(游離脂肪酸)and

Pigment(脂溶性色素).Lipid

exists

as

two

forms:

deposited

fat

(stored

fat)and

tissue

fat

(fat

between

muscle

fibre).

The

latter

makesmeatsoft

and

dulcet.College

of

Animal

Science,Dr

Aifang

Du2010-12-1319(3)GlycogenOnly

less

than

1%

glycogen

exists

in

meat,

most

of

whichexists

in

animals,tissues

or

tissue

fluid

as

dissociated(游離)or

combined

form.Glycogen

(animal

starch淀粉)mostly

stores

in

liver

andmuscle.

Though

there

is

low

content,

glycogen

plays

a

veryimportant

role

in

the

storage

and

processing

of

meat

andmeat

products.The

more

pre-slaughter

animals

rest

have,

the

moreglycogen

it

has

in

meat.

This

is

good

for

the

quality

of

meatas

well

as

the

storage and

processing

of

meat.College

of

Animal

Science,Dr

Aifang

Du2010-12-1320（4）

MineralsThe

content

of

minerals

inmeat is

about

1%.The

primary

macroelement（常量元素）：

Ca,P,

K,

Na,

Fe,

Mg, S,

Cl,etc.The

microelement（微量元素）

:Mn,

Cu,

Co,Zn,

etc.College

of

Animal

Science,Dr

Aifang

Du2010-12-1321(5)nitrogenous

extract

and

nonnitrogenousextractMain

nitrogenous

extract

：The

more

nitrogenous

extract

is,

the

stronger

it

smells.Th

r

activates

appetite

and

facilitatesthe

secretionof

gastric

juice(胃液).(6)

Vitamins(維生素)Muscle

and

viscera

are

the

source

of

mostvitamin

Bliver

is

a

good

material

for

acquirementof VA

and

VC

.College

of

Animal

Science,Dr

Aifang

Du2010-12-13243.Edibleness

of

meat(肉的食用意義)A

little

vitamin

is

kept

in

meat,

especially

the

VB.Viscera

contains

VA

and

VD.Lipid

in

meat

with

high

digestibility（消化率）,promotes

thepalatability(適口性)andcan

bealso

usedas

an

energy

source.Overmuch

fat

affects

the

taste

andeven

the

digestion.With

the

characteristic

of

high

digestibility,

greatpalatability,

starvation

tolerance

and

product

variety,meat

has

a

very

high

food

content,

providing

abundantgross-value

protein,

fat,

minerals

and

vitamins.College

of

Animal

Science,Dr

Aifang

Du2010-12-1326Section

2Post-slaughter

changes

in

meat(宰后肉的變化)tissuCollege

of

Animal

Science,Dr

Aifang

Du2010-12-13281.Meaty rigor

(肉的僵直)Autolysis

enzyme(自體分解酶)glycogenolytic

fermentlactic

acidphosphorylase(磷酸化酶)Meaty

Acidic

Ultimate

pH（肉的酸性極限pH值）During the

process

of

meat

rigor,

theinheritance（遺傳特性）,meattemperature

and

storage

together

withother

meat

can

affect

the

descent

rate

ofpH.Animal

species,

age,

circumstancetemperature,

pre-slaughter

conditionsand

the

means

of

slaughter

all

affect

theoccurrence

and

duration

of

rigor.College

of

Animal

Science,Dr

Aifang

Du2010-12-1335Slaughtered

meat（宰后肉）Acidic

Ultimate

pH（酸性極限pH值）（Lactic

acid（乳酸）phosphoric

acid（正磷酸）Process

of

meaty

rigor2.

Meaty

ripening（肉的成熟）ConceptProcess

of

meaty

ripening(肉的成熟過程)Bio-Chemical

changesripening

(肉成熟過程中的變化)in

meatyPrecipitation

of

muscle

juice(肉汁的析出)：Under

the

influence

of

acid

medium,calciumsegregates(脫離)from

proteins,

and

whiakepartial

myosin(肌凝蛋白)coagulates(凝結)and

formsthe

dilute

solution（稀溶液）which

is

not

soluble

tostroma(不溶于基質).Then,

fluid

section

ofcarcoplasm(肌漿)separates

out,

leading

to

effusion(滲出)of

precipitation

from

transection

of

meat,whichmakes

transection

moist,

after

bloodlettin o

or

threedays

.College

of

Animal

Science,Dr

Aifang

Du2010-12-1340Softening of

connective

tissue(結締組織軟化):The

acid

medium

increase

the

penetrability(滲透性)

ofthe

cell

and

connective

tissue,

which

promote

thedistention(膨脹)

and

softening

of

the

connective

tissueand

also

softening of

meat.The

third

day

after

bloodletting,highly

volatile(易揮發(fā))and

lyotropic（易溶）

enzymes

and

aldehydes（醛類）are

generated

remarkably

under

the

influence

of

otherenzymes,

making

the

meat

delivering

characteristicaromatic

odor(芳香氣味).College

of

Animal

Science,Dr

Aifang

Du2010-12-1341Character

of

meaty

ripening

and

its

significanceinnutritionalhygiene(成熟肉的特征及其營養(yǎng)衛(wèi)生意義)①Character

of

ripe

meat（成熟肉的特征）：②significance(意義)：what

can

affect

the

meaty

ripening

?①pre-slaughter

condition

(動物屠宰前的狀況)：②Environmental

temperature(環(huán)境溫度)：3.

Meaty

autolysis

and

acidfermentation(肉的自溶和酸性發(fā)酵)(1)

Nigrescence

with

autolysis(自溶性變黑)Meaty

autolysis

often

occurs

when

carcass

was

stackswithout

thoroughly

chilling(冷卻),especially

carcass

ofovergrowth(肥大).That

H2S

or

thioalcohol（硫醇）

combined

withhemoglobin（血紅蛋白）

formssulfhemoglobin(硫血紅蛋白)makes

fat

layer(脂肪層)with

severe

autolysisturn

to

dull

green

color(污綠色).Characters

of

meat

with

autolysis:

dull

muscles

(暗淡,無光澤),

maroon

(褐紅色) ray

red(灰紅色)

ormignonette(灰綠色),

odor

with

strong

acids,

H2Spositive,

ammonia

negative(氨).College

of

Animal

Science,Dr

Aifang

Du2010-12-1347(2)

Acid

fermentation

of

meat(酸性酵解)：Acid

fermentation

is

similar

to

autolysis

butdifferent

from

spoilage.

In

the

process

ofautolysis,

proteins

are

just

posed

intosoluble

nitrogen(可溶性氮)

or

amino

acids.

Itmakes

a

balance

between

proteins

and

solublenitrogen

or

amino

acids. Autolysis

carries

onoes

with

the

meat

ripening.

There

is

nolimit

between

autolysis

and

meat

ripening,

aswell

as

between autolysis

and

spoilage

.College

of

Animal

Science,Dr

Aifang

Du2010-12-1349Meat

with

strong

abnormal

flavor

and

severedarkening

can’t

sale.

It

mustbe

treated

withhigh

temperature

or

professional

processingbefore

cooking.If

the

meat

was

light

discoloration(變色)orstaleness(變味),the

meatwas

divided

intopieces

and

placed

at

ventilated

local

to

disperse(驅散)the

abnormalflavor.College

of

Animal

Science,Dr

Aifang

Du2010-12-13504.

Meaty

spoilage

(肉的

)(1)

processofmeat

spoilageProteins are

hydrolyzed

（水解）into

AADue

to

deamination(脫氨作用),decarboxylization

(脫羧作用)

and

positioneffect

(分解作用),

further posed

products,such

as benzopyrrole

(吲哚),methylindol

(甲基吲哚),

alcohol

phenyl

(酚),tetramethylenediamine

(腐胺),pentamethylenediamine

(尸胺),hydroxyphenylethylaminem

(酪胺),

beta-imidazolyle

thylamine

(組胺),aminoethylindole(色胺),all

kinds

ofnitrogenous

acids

andfatty

acids,

are

formed

.College

of

Animal

Science,Dr

Aifang

Du2010-12-1352H2S,CH4

(甲烷),NH3,thioalcohol(硫醇)andCO2,etc.Spoilage

is

the

process

in

which

theproteinsare posed

with

the

effect

of

protease(蛋白酶)and

endopeptidase

in

microbe(肽鏈內切酶).College

of

Animal

Science,Dr

Aifang

Du2010-12-1353①Amines(胺類)Be

noxious

to

human

body,

which

cause

hypertension(高血壓).Tyr

(酪胺酸)phenol(苯酚)noxious

to

human

bodyTricresol(甲苯酚),Phenol(苯酚)Hydroxyphenylethylaminem（酪胺）②Phenols（酚類）③benzopyrrole(吲哚),methylindol(甲基吲哚)Cys(半胱氨酸)

is posed

into

H2S,

CH4

andthioalcohol

(硫醇)

via

deamination(脫氨)

ordecarboxylation

(脫羧).AA

deaminate(脫氨)into

ammonia(氨).All

of

above

products

are

excrement

in

animal.

Apartial

undigested

or

unabsorbable

proteins

areposed

by

microbe

in

inferior

part

ofintestinum

crassum(大腸下部).These

matters

are

the

metabolic

products

ofbacteria

during

the

spoilage

.College

of

Animal

Science,Dr

Aifang

Du2010-12-1357④H2S,

CH4,NH3,thioalcohol(硫醇)and

CO2,etcBesides

foul

smell

made

by

the

posing

of

protein,spoilage

also

brings

the

changes

as

following:(2)

Contaminative

styles

of

meat①Contamination

before

slaughter(宰前污染)②post-slaughter

contamination(宰后污染)(3)

Curve

of

meat

spoilage

(肉的

分解曲線)Curve

of

meat

spoilageWater

content,

pH,

temperature

and

microbecontamination

will

influence

the

speed

of

meat

spoilage.(4)

character

of

spoiled

meat（

肉的表征）Rigor

of

Meat（尸僵）Ripening

of

Meat（成熟）Meat

spoilage（

）Meat

autolysis（自溶)Meatchange

process

post-slaughterOxygen-demandingcoccobacteria(需氧球菌)E.coli(大腸桿菌),Bacillus

proteus(普通變形桿菌)and

aeruginosus

bacillus（綠膿桿菌）aerotolerant

anaerobe(兼性厭氧菌）：Bacillusperfringens(產(chǎn)氣莢膜桿菌)和bacillus（芽孢桿菌）Anaerobic(厭氧菌)Microbiology

change

in

meat