Chapter 9 - Meat Tenderization ANSC 307

What factors can we disrupt to make meat more tender

~ cause the sarcomeres to be longer

~ Disrupt the integrity of the myofibrils

~ Disrupt the integrity of the connective tissue

Define cold shortening

Process whereby sarcomeres shorten due to cold-induced nervous response. Results in tougher meat.

How to prevent cold shortening

Speed-up drop in pH in muscle (anaerobic glycolysis: glycogen → lactic acid; muscle pH 7.0 → 5.6). AND/OR Slowdown drop in muscle temperature.

What do you do if you want cold-shortened meat?

~ slow-down the drop of the pH in the muscle

~ Speed up drops in muscle temperature

Based on the chart. What is the optimal temperature to reduce cold shortening?

16 degrees Celsius

How to cause the sarcomeres to be longer

~ Prevent cold shortening

~ Stretch the sarcomeres

How do you prevent cold shortening?

~ Subcutaneous fat thickness - Slows down temperature drop in muscle.

~ High temperature, pre-rigor chilling - 16°C for 16 hours immediately after slaughter.

~ Electrical stimulation - 550 volts, 2 to 6 amps, 15 times in one minute. Very rapid drop in muscle pH and quicker onset of rigor mortis. (9 hours)

When does rigor mortis set in

after 16 hours

(T/F) Pork can cold shorten

False, pork doesn’t cold-shorten because of “white” muscle fibers

what is the subcutaneous fat thickness in lamb?

0.1 in

what is the subcutaneous fat thickness in beef?

0.25 in

How do we stretch the sarcomeres

~ Texas A&M Tenderstretch - suspension by the obturator foramen. Hindleg acts as a cantilever.

~ Stouffer's Stretching Devices - TAMU Tenderstretch plus clamps and stretching rods.

~ TenderCut™ - bones and connective tissues are cut around muscles to allow stretching.(hang by the bone instead of the Achilles tendon)

How do we disrupt the myofibrils?

~ Increased activity of endogenous enzymes

~ Addition of exogenous enzymes

~ Severance of myofibrils

What are the endogenous enzymes we use to disrupt myofibrils and describe them

~ Calpains - stored in the cytosol near Z-lines and require calcium to be activated

~ Calpastatin - regulates calpains; the higher the calpastatin levels and activity, the less breakdown of myofibrils.

How do we increase the activity of endogenous enzymes

~ Cooler aging – storage for 1 to 6 weeks at 0-3°C.

~ High temperature, post-rigor chilling – Storage at 20°C for 24 hours. Same effect as 2°C for 14 days.

~ High temperature, pre-rigor chilling – 16°C for 16 hours.

~ Electrical stimulation – rapid pH decline ruptures lysosome and releases cathepsins.

~ Calcium chloride infusion/injection – pre-rigor infusion or post-rigor injection of a solution of calcium chloride into muscle. Causes increased activity of calpains.

What exogenous enzyme is found in papaya

Papain

What exogenous enzyme is found in pineapple

Bromelin

What exogenous enzyme is found in fig

Ficin

What exogenous enzyme is found in kiwi fruit

Actinidin

What tropical plant enzymes (exogenous enzymes) are heat activated (starts to degrade the proteins)?

~ Swift's Pro-Ten® (inject into live animal)
~ Adolph’s Meat tenderizer (sprinkle on meat)

What methods are used to severe myofibrils

~ Electrical stimulation

~ Blade or needle tenderizer

~ mechanical severance

~ Hydrodyne™

How does electrical stimulation severe myofibrils?

violent contractions cause myofibril tearing.

How does Blade or needle tenderizer severe myofibrils?

machines with multiple blades and/or needles that penetrate meat as it passes through on a conveyor. First machine was Jaccard (most people call the process “Jaccarding”).

How does Mechanical severance severe myofibrils?

scoring, dicing, cubing, grinding or chopping.

How does Hydrodyne™ severe myofibrils?

placing meat in a sealed water-filled chamber and setting off an explosion. Destroys most of the Z-lines to greatly improve tenderness.(not an easy thing to do)

What methods do we use to disrupt connective tissue (not an easy thing to do)

~ Use of exogenous enzymes

~ Severance of stromal proteins

~ Conversion of collagen to gelatin

what exogenous enzymes do we use to disrupt connective tissue?

~ Marination with salt and vinegar – water solution with 2% NaCl plus acetic acid.

~ Rhozyme use of fungal enzyme: Aspergillus oryzae. (best way to disrupt connective tissue)

~ Tropical plant enzymes

How to we severe stromal proteins?

~ Blade or needle tenderization

~ Mechanical severance

How do we convert collage to gelatin?

Moist-heat cookery – cook for a long time with steam generation: braise, stew, simmer

What does modern meat science focus on?

Eating quality (tenderness)

What did meat science in the past focus on?

~ Aging

~quanitiy