MEATS, FISH & POULTRY

HTF573

OUTLINE• CLASSIFICATION• STRUCTURE• PIGMENTS• FACTORS AFFECTING QUALITY• PREPARATION

CLASSIFICATION

• Flesh food categorize as:– Meat– Poultry– Fish

• Meat include all red meat (beef, veal, pork & lamb/mutton) from animal sources.

• Poultry include turkey, chicken & duck, pheasant & other available fowl.

• An aquatic animal;– Fish: fin, gills, a backbone & skull– Shellfish: mollusks; shell crustaceans; horny covering

STRUCTURE

Muscle Tissue

Component %

Water 75

Protein 18

Fat 4-10

Carbohydrate 1

Mineral & vitamin <2

Muscle Tissue• Protein

Myosin Principal myofibrillar protein

Actin Myofibrillar protein existing primarily in form (F & G)

Tropomyosin Least abundant of the three principal myofibrillar proteins

Actomyosin Muscle protein formed from the union of actin & myosin during muscle contraction

ATPase Enzyme in muscle tissue involved in glycolytic reaction leading to lactic acid formation

Pyrophosphatase Enzyme in muscle tissue influencing the water holding capacity of meat

Cathepsins Proteolytic enzymes that can catalyzed hydrolytic reaction leading to the passing of rigor mortis

Calcium-activated factor (CAF)

Proteolytic enzyme activated by calcium contribute to tenderizing of aging meat

Muscle Tissue

4 is Myofibrillar = muscle protein

Thin filament = actinThick filament = myosin

Muscle Tissue• Protein

Myofilament Simplest level of organization in muscle ; thick or thin myofilament

Thick myofilament Longer type of myofilament , composed of myosin molecules joined together

Thin myofilament Form by the helical twisting of two strand of polymerized actin

Myofibril Linear bundle of several myofilament that contain number of sacromeres

Sarcomere Portion of myofibrils consisting of the area between two Z line

Z lines Region in myofibril where the thin myofilament of actin adjoin, creating a dark line that define the end of a sacromere

I band The light region on the other side of Z line in a sarcomere, no overlapping of myofilament of actin

Muscle TissueH band Region in the center of sacromere where only thick

myofilament of myosin occurA band Total portion of the sacromere in which thick & thin

myofilament overlap, include H bandFiber Bundle of myofibrils & sacroplasm encase in the

sarcolemmaSarcoplasm Jellylike protein surrounding the myofibrils in muscle fiber

sarcolemma Thin, transparent membrane surrounding the bundle of myofibrils that constitute a fiber

Connective tissue• Proteins

collagen Fibrous protein composed of 3 strands of tropocollagen

elastin Yellow connective tissue occurring in limited amounts intra-muscularly & greater concentration in deposits outside the muscle

reticulin Associated with fatty acid (myristic acid)

ground substance Undifferentiated matrix of plasma protein & glycoprotein in which fibrous molecules of a collagen and/or elastin are bound

• The nitrogen in either proline or hydroxyproline is involved in the primary structure of the strand of tropocollagen

• The planar rigidity of the pyrrolidine ring prevents the bond angles that lead to the usual α–helix & spherical nature of mist food protein.

Connective tissue• Organization

– Binding componenti. Sarcolemma (encase fiber)ii. Endomysium (between fiber)iii.Perimysium (surround bundle of fiber)iv. Epimysium (surround many bundle of fiber to

encase muscle)

Connective tissueMyofilament

Sarcometes

i. Thick (myosin)

ii. Thin (actin)

i. Z lines

ii. I band

iii. H band

iv. A band

Myofibrils

Sarcoplasma

Fiber Bundle of fiber

Muscle (bundle of bundles)

Connective tissue

Cross section of muscle

Fat • Lipid found in muscle tissue• Fatty acids found most abundantly in triglycerides

in the fat depots; oleic (18:1), palmitic (16:0) & stearic (18:0).

• In the cell, the lipid & lipid component deposited in a matrix of connective tissue, primarily collagen.

• Fat contribute to juiciness & flavor of meat. Also in nutrition perspective.

PIGMENTS

Myoglobin & Related CompoundsMyoglobin Purplish-red pigment consisting of heme containing ferrous

iron & polypeptide polymer (globin)

Heme Compound composed of four adjoining pyrrole rings to an atom of iron

Hemoglobin Very large, iron-containing compound consisting of four heme-polypeptide polymers linked together; contribute to colour of meat

Oxymyoglobin Cherry red form of myoglobin formed by the addition of two oxygen atom.

Metmyoglobin Brownish red form of myoglobin formed when the ferrous iron is oxidized to the ferric form & water is complexed to the oxidized iron

Astaxanthin Redish orange carotenoid pigment in salmon & in cooked crustaceans.

hemoglobin

Changes effected by heating• While meat being cooked, heat change the pigments.

• Denatured globin hemicrome;– Myoglobin derivative formed when heat triggers the

oxidation of iron to the ferric (Fe3+) state & denatures the globin portion of the compound while the oxygen of oxymyoglobin is replaced with water complexed to the iron atom (result in gray brown colour).

Changes effected by heating• Heating enhance the light colour of fish by

increasing opacity• Crustacean (crab, lobster, shrimp); blackish-green caratenoid pigment (orange) astaxanthin become dominant• Poultry; colorless when cooked

– If has been frozen, some hemoglobin has leaked from marrow

– Hemoglobin in the flesh close to the bone– Become dark when cooked– For very intense heat during preparation ,develop a

raddish-pink color– Hemoglobin react with carbon monoxide + nitric oxide,

generate by electri hating/ flame when barbecuing

Changes effected by curing• Process involved treatment with either nitrates or

nitrites to preserve meat for long term storage.• Nitrite is function to prevent botulism in cured meat

Changes effected by curing• Nitric oxide (nitrites + nitrates) combine with

myoglobin to form nitric oxide myoglobin.• Nitric oxide myoglobin change to nitric oxide

myochrome (stability of pinkish-red) when 2nd nitroso group replace the globin during slow heating in curing.

• Expose to lightb& air, oxidation of ferrous to ferric state (dev of brownish color)

• Expose to light & additional O2 hasten the breakdown of pigments

• Light promote removal of nitroso from pigment• Fe2+ to Fe3+ caused discoloration

FACTORS AFFECTING QUALITY

Maturity • Young animal;

– have low ratio of lean to bone– Large amount of connective tissue & little fat

• Veal; < 3 years old• Lamb; 14 month• Mutton; >2 years• Pork; 6 month or slightly older

Maturity As animal mature:• The increase fat content raised ;

– influence the flavor of meat, contribute to apparent juiciness, moisture content decrease.

• Connective tissue; increase in total amount but smaller % then were present when was young.

• Less tender (increase formation of cross-linkages between fiber of collagen within the lean muscle)

• Flavor changes, fat content influence this. (stronger characteristic flavor)

• Color become redder & darker• pH of muscle decrease

Postmortem changes• Biochemical process continue several hours after

slaughtering • Influence the quality of meat• The level of glycogen store in the animal at the time

of slaughtering is important in determining onset of rigor mortis & factors in meat ready to be marketed.

• Rigor mortis; temporary rigidity of muscle that develop after death of an animal

• The onset of rigor mortis differ between species

• Fish; – rigor mortis extend (ice as soon as they are killed)– Maintain in chilled storage– Extend remain fresh (bacteria commences after rigor

mortis has passed)– Not more then 7 days to maintain freshness

• Poultry;– Slower than fish– After at least 4 hours have elapsed (turkey 12 h)– Cooking & freezing should not began until rigor mortis

has passed; the flesh will be tough– Prompt chilling by immersion in ice water bath, retarding

rigor mortis & achieving tenderness• Pork;

– Aged at least 1 day, to pass through rigor mortis• Beef;

– Various muscle exhibit different behavior– Need to be aged 11 days, achieve max tenderness

• Desirable storage – Ultraviolet light, control microbial growth– Control humidity of 70%– Temperature just above freezing

• Beef may be held at temperature of 16C for 16 to 20 hours after slaughter before being aged at 2C

• Electric stimulation (100-600 volts) for 1-2 min within 45 min after slaughter to promote tenderness in poultry & meat– Fast muscle contraction (physical & biochemical changes)

• Meat chilled rapidly after slaughter, muscle contract drastically (cold-shortening)

• tenderness enhanced by hanging, so the muscle are stretched & resting state prior to onset of rigor

• Color can be influenced by pH.– Beef; final pH at 6.6, deep red, almost black in the flesh,

sticky & slimy feeling– Dark-cutting beef

PREPARATION

Changes effected by heat• When meat are heated, fat soften & melts and

proteins are denatured. • Water is lost. Some conversion of bound water to

free water as the water-binding capacity is reduces.• The new available free water off sets the water lost

in the early cooking & meat remain juicy• When reach 74-80C, bound water convert to free

water very rapidly• Muscle fiber; shrinkage (55C until 80C) & cracking

of I band (mealy chacter)• Muscle protein; less tender

– 40-50C; myosin become less soluble, hydration decrease– 65 to 75C; affecting tenderness

Changes effected by heat• Connective tissue

– Elastin as not modified– Collagen slowly change (moist heat), H bond began to

break tropocollagen. Gelatin component of collagen begin to move away from each other

– Can be seen when dripping from post roast are refrigerated, cause gelatin to form gel

• Fish; major effect in muscle protein– Just heat fish until it flakes, – Softening of collagen permit easy separation of fiber– Denaturation of the muscle also occurs– At this point, the flesh still tender– Continue heating cause toughness

Changes effected by heat• Dry heat

– To maximize the quality of muscle protein– Tender cut of meat; high proportion of muscle protein &

reduce collagen– Only in roasting; higher opportunity to convert collagen to

gelatin– Microwave; greater cooking losses & less juiciness– Broiling; greater cooking lost when at high temperature

• Moist heat– Braising / stewing; sufficient time or collagen to be

converted to gelatin without toughening the muscle protein

– The liquid prevent surface become hot to dry & brown– Poaching or steaming; for fish

Effects of altering pH• Hydration of meat important to evaluation of

juiciness in product• Alkaline ingredient added,

– color is darkened & – influence on hydration is minimal.– Increased tenderness does not develop (add soda not

recommended)• Acid ingredient added,

– Increased juiciness & tenderness– Negative effect on aroma, flavor

Effect of salt• Major effect is enhanced water retention• Ability to hold water in the meat to improve

juiciness• Minor role in promoting tenderness• Palatability

Meat tenderizers• Ezymes

– Most common is blend of enzyme from papaya & salt (papain)

– The 3 enzymes in this substance; chymopapain, papain & peptidase

– Applying it to the surface of the meat & piercing the meat repeatedly with fork (to carry the enzymes into the interior)

– Others; • bromealin - in fresh pineapple (kabob & stir-fried

chicken)• ficin – in figs

• Papain • has little effect at room temperature, • active when reach 55°C & increases in activity at

higher as 80°C. (inactive at 85°C-denatured)• Effect;

– result of destroying the sacrolemma surrounding the myofibrils in the fiber

– Hydrolyzing actomyosin– Continuing hydrolytic breakdown of various proteins

in the fiber– Collagen also may be hydrolyzed to contribute still

further to the tenderizing effect– Development of mushy texture

Meat tenderizers• Mechanical tenderization

– through tenderizer equipped with needles or blades, to cut connective tissues & increase tenderness

– Change the texture, but not produce mushy characteristic

– Cubing, fair portion of muscles , to increase tenderness

– Example; grinder. Shearing of the fibers & connective tissue – very tender meat from cut.

Prepared By

NORISTISARAH ABD SHATTARLecturer

FPHP UiTMT noristisarah@yahoo.com

noris590@tganu.uitm.edu.my