Meat Science- Exam 3

What is meat processing?

Alters meat by mechanical/chemical/enzymatic methods

What is value-added meat?

Processed to increase market value

What is the raw material in meat processing?

Carcass/meat before processing

What are the main purposes of value addition?

Value, variety, shelf life, efficiency

What are the main functions of meat processing?

Preserve, improve, safety, convenience

How is shelf life extended?

Chilling, packaging, antimicrobials, antioxidants, irradiation

What is MAP packaging?

Modified atmosphere packaging

What does vacuum packaging do?

Removes oxygen

How do you improve tenderness?

Tenderization

How do you improve juiciness?

Injection

How do you improve flavor?

Marination

What is the most common safety process?

Cooking

What does RTC mean?

Ready-to-cook

What does RTE mean?

Ready-to-eat

What does IQF mean?

Individually quick frozen

What is minimal processing?

No chemical change

What is further processing?

Chemical change/additives

What are sensory qualities?

Color, tenderness, juiciness, flavor

What are technological qualities?

Binding, emulsifying, texture

What is stress in animals?

Response to adverse conditions

What causes stress?

Handling, temp, noise, fasting

What hormones are involved in stress?

Epinephrine, norepinephrine

What metabolism occurs during stress?

Glycolysis

What is PSE meat?

Pale, soft, exudative

What causes PSE?

Rapid pH drop

What is DFD meat?

Dark, firm, dry

What causes DFD?

Slow pH drop

What is WHC?

Ability to hold water

Why is WHC important?

Texture, yield, juiciness

What is bound water?

Tightly held (~4-5%)

What is free water?

Surface water

What is the isoelectric point?

pH where charges equal

What happens to WHC at isoelectric point?

Lowest WHC

What happens when pH increases?

Higher WHC

What happens when pH decreases?

Lower WHC

What is protein net charge?

Usually negative

Why is temperature controlled?

Prevent spoilage

What does high temperature cause?

Microbes, oxidation, denaturation

What is thaw rigor?

Toughening after thawing pre-rigor

What is cold shortening?

Cold-induced contraction

What is homeostasis?

Stable internal conditions

What factors control homeostasis?

O2, pH, temp, energy

What starts postmortem changes?

Exsanguination

What happens to oxygen after death?

Decreases

What metabolism occurs postmortem?

Anaerobic glycolysis

What builds up postmortem?

Lactic acid

What causes pH decline?

Lactic acid

What is normal pH decline?

7.0 → ~5.5

What is ATP used for in muscle?

Relaxation

What happens when ATP is gone?

Rigor mortis

What is rigor mortis?

Muscle stiffening

Why does rigor occur?

No ATP

How many binding sites in rigor?

100%

How many in normal contraction?

~20%

What are rigor phases?

Delay, onset, completion

What causes meat to become tender after rigor?

Protein breakdown

What is myoglobin?

Oxygen-binding muscle protein

Where is myoglobin found?

Muscle

What is the heme group?

Iron-containing structure

How many binding sites does iron have?

6

What does proximal histidine do?

Binds iron

What does distal histidine do?

Stabilizes O2

What is deoxymyoglobin color?

Purple

When does it occur?

Low oxygen

What is oxymyoglobin color?

Bright red

When does it occur?

High oxygen

What is metmyoglobin color?

Brown

When does it occur?

Oxidation

What is blooming?

Exposure to O2 → red color

What does CO binding form?

Bright red color

What does NO binding form?

Pink cured color

What determines meat color?

Myoglobin + O2 + iron state

What does oxidation do to meat?

Turns brown

What does reduction do?

Restores red

What limits shelf life?

Microbes, oxidation, moisture loss

What is oxidation in meat?

Rancidity + color change

What is spoilage?

Off odor, texture, color

What is emulsifying capacity?

Mix fat + water

What is binding ability?

Hold structure

What is cooking loss?

Weight loss from cooking

What is drip loss?

Liquid loss

What is glycogen role?

Energy source

What happens with low glycogen?

DFD

What happens with high glycogen?

PSE

What is postmortem metabolism?

Anaerobic

When does it stop?

ATP depleted

What causes temperature rise postmortem?

Metabolism

What increases microbial growth?

High temp

What is cold shortening caused by?

Cold + low ATP

What is thaw rigor caused by?

Freezing pre-rigor

What is stunning?

Render animal unconscious

What is goal after stunning?

Rapid bleeding

What is blood splash?

Blood spots in meat

What is product functionality?

Texture + structure

What affects flavor?

Processing + ingredients

What is convenience processing?

Easier preparation

What is sous-vide?

Cook in sealed bag

What is commercially sterile?

No microbes present

Why is meat color important?

Consumer acceptance

What does color indicate?

Freshness