ANS 3614- (3) postmortem tenderization

what is the difference among muscles?

actomyosin effect

background effect

bulk density

what is the actomyosin effect?

the state of contraction when rigor occurs

measured in 3 ways

what is rigor mortis?

the death stiffening process

the membrane degrades, leaking calcium, ATP is left over so muscles continue to contract until it’s used up, muscles stiffen because actin and myosin can’t release from each other

how is the actomyosin effect measured?

sarcomere length: the more it’s contracted, the more shear force required to shear the muscle

muscle fiber diameter: stretched muscle has a smaller diameter, more tender

fragment: smaller fragment means more tender meat

what is the background effect?

the amount and state of connective tissue (stromal proteins)

more the muscle is used (ex. locomotion)=more stromal proteins present=more tough meat

3 types of connective tissue

what are the 3 types of connective tissue (stromal proteins)?

collagen: white, highly organized, some cross-linking

reticulin: immature collagen, silver, highly organized, some cross-linking

elastin: yellow, unorganized, lots of cross-linking

what is the bulk density?

amount of fat present in the meat

the more you cook a steak, the tougher it is

measured in 3 ways

how does fat act as an insulator and lubricant?

fat as an insulator: slows down negative effects of heat during cooking (drying out)

fat as a lubricant: stimulates saliva production, when cooked it will liquify and act as a lubricant

how is bulk density measured?

amount of marbling in the muscle, amount of moisture, water holding capacity

what are the 3 major palatability attributes of meat?

tenderness (most important), juiciness, flavor

what can differences in tenderness be attributed to?

actomyosin effect, background effect

antemortem factors: heritability, breed type, managemental practices (nutrition, feeding program, animal handling, etc.)

what factors influence tenderness postmortem?

cold shortening, rate of chilling

what is cold shortening?

process whereby sarcomeres shorten due to cold-induced nervous response, results in tougher meat

stimulates release of calcium (muscle contraction)

how does cold chilling stimulate the release of calcium?

the colder it is, the harder it is to get calcium back into the sarcoplasmic reticulum

how does the rate of chilling decide cold shortening?

delayed chilling facilities: meat held at 70-75 F for 3-5 hours prior to chilling

high temp. conditioning: carcasses held at 50-60 F for 12-18 hours postmortem

carcasses with at least .3in of fat insulates muscle to prevent cold shortening

how do you prevent cold shortening?

speed up the drop in pH in the muscle, slow down the drop in muscle temperature

how can you make meat more tender?

cause the sarcomere to be longer

disrupt the integrity of the myofibrils

disrupt the integrity of the connective tissue

prevent cold shortening

what is high temp. pre-rigor chilling?

hold carcass at 16 C for 16 hours immediately after slaughter to make meat more tender

not done in the US or Canada (food safety risk)

what is electrical stimulation postmortem?

speed up postmortem metabolism by causing muscle contraction to make meat more tender

electrical impulses passed through carcass causing contraction which causes accelerated postmortem glycolysis

rapid drop in muscle pH and quicker onset of rigor mortis

what is needed for electrical stimulation postmortem?

550 volts and 2-3 amps, 15 times in one minute

what stretching methods (of the sarcomeres) are used?

Texas A&M Tenderstretch

Stouffer’s Stretching Devices (TAMU)

TenderCut

what is the Texas A&M Tenderstretch?

the carcass is suspended by the aitch bone instead of achilles tendon

stretches the muscles of the round and loin to increase sarcomere length and increase tenderness

what is the Stouffer’s Stretching Device (used by TAMU)?

Tenderstretch plus clamps and stretching rods

what is the TenderCut?

bones and connective tissues are cut around muscles to allow stretching

what enzymes are used to disrupt the myofibrils?

endogenous: calpains, cathepsins, calpastatin

exogenous: papain, bromelin, ficin

what are the endogenous enzymes?

activated postmortem

calpains: stored in sarcoplasm near Z lines, need calcium to be activated

cathepsins: stored in lysosomes, breakdown actin-myosin bonds

calpastatin: higher levels and activity=less breakdown of myofibrils

what are the exogenous enzymes?

tropical plant enzymes used to enhance the tenderness of meat, heat-activated

papain: from papaya, bromelin: from pineapple, ficin: from fig

added using Swift’s pro-ten and Adolph’s meat tenderizer

what is Swift’s pro-ten?

adds exogenous enzymes by injecting them into a live animal

what is Adolph’s meat tenderizer?

adds exogenous enzymes by sprinkling the tenderizer on the meat

what is aging?

the process that utilizes endogenous enzymes to enhance tenderness of meat by breaking down some of the myofibrillar structure

takes 2 weeks

what temperature is aging done at?

fridge temp

high temp. post-rigor chilling: store at 20C for 24 hours, same as 2C for 14 days

high temp. pre-rigor chilling: store at 16C for 16 hours

what is calcium chloride infusion/injecting?

pre-rigor infusion or post-rigor injection of a solution of calcium chloride into muscles

causes increase activity of calpains (exogenous enzyme)

what are the 2 ways of disrupting the myofibrils?

using enzymes and using severance

how is disruption of the myofibrils using severance done?

blade tenderization

blade or needle tenderizer

electrical stimulation

mechanical severance

hydrodyne

what is blade tenderization?

a process that uses small knives to disrupt the tissue

commonly used for food service products

what is blade or needle tenderizer?

machines with multiple blades and/or needles that penetrate meat as it passes through on a conveyor

first machine=Jaccard (ex. Jaccarding)

what is electrical stimulation?

violent contraction causing myofibril tearing

what is mechanical severance?

scoring, dicing, cubing, griding, chopping

what is hydrodyne?

placing meat in a sealed-water filled chamber and setting off an explosion

destroys most of the Z-lines to instantly tenderize

safety concern…

how do you disrupt the connective tissue?

use of exogenous enzymes

marination with salt and vinegar

fungal enzymes

tropical plant enzymes

describe marination with salt and vinegar

2% solution of NaCl plus acetic acid in water

causes a change in connective tissue depending on the time

less than 4 hours then flavor only

more than 4 hours for tenderness

colder temperatures take longer, warmer temperatures take shorter but have a bacterial risk

describe the use of fungal enzymes

rhozyme: use of fungal enzyme Aspergillus oryzae

has collaginase and elastinase

will breakdown connective tissue components

describe tropical plant enzymes

bromalin from pineapples

papain from papaya

ficin from figs

what are the drawbacks of disrupting the connective tissue?

increases purge in the package

bacterial risk (outside brought inside by needles or blades)

have to cook to same internal temperature as ground beef

what is the conversion of collagen to gelatin?

moist-heat cookery: cook for a long time with steam generation

holds moisture in, steam changes collagen into gelatin

braise, stew, simmer, crock pot