Conversion of Muscle to Meat

ATP (adenosine triphosphate)

chemical energy source for muscle contraction in living animals

ADP (Adenosine Diphosphate)

the low-energy byproduct when ATP releases energy to power muscle fibers

Phosphagen Systems

the immediate, short-lived energy system in skeletal muscle that acts as the first line of defense to maintain ATP levels post-slaughter

Glycolysis

the anaerobic metabolic process where stored glycogen is broken down to generate energy after slaughter

Mitochondrial Respiration

the postmortem continuation of cellular oxygen consumption

Phosphocreatine

a high energy “temporal buffer” that rapidly regenerates ATP to maintain muscle energy levels immediately after slaughter

Creatine Kinase

an enzyme in animal muscle that catalyzes energy production, acting as a key marker for pre-slaughter stress and muscle damage

Adenylate Kinase (myokinase

a highly active enzyme in muscle tissue that plays a critical role in the transition from muscle to meat by managing energy metabolism

AMP (adenosine monophosphate)

a nucleotide that plays a critical role in the conversion of muscle to meat, acting as a signaling molecule to regulate energy metabolism, pH decline, and development of meat quality traits

Aerobic Metabolism

the initial post-mortem phase where remaining oxygen allows cells to break down nutrient to produce energy

Tricarboxylic Acid Cycle (TCA)

a mitochondrial metabolic pathway that produces ATP from oxidative phosphorylation by oxidizing Acetyl-CoA from carbs and fat

Alt Name: Krebs Cycle, Citric Acid Cycle

Glycogen

a stored carb in the living muscle that upon slaughter, converted into lactic acid, reducing the muscle pH

Glycogenesis

the process of synthesizing glycogen from glucose, which stores energy in muscle tissues while the animal is alive

Glycogenolysis

the postmortem breakdown of stored glycogen into glucose-1-phosphate, which feeds into anaerobic glycolysis to produce energy; glycogen breakdown

Glycogen phosphorylase

the key muscle enzyme that initiates glycogenesis by breaking down glycogen into glucose-1-phosphate to provide energy for muscle activity

Anaerobic Metabolism

the involuntary, oxygen-free process where muscle tissue breaks down glycogen into energy, producing lactic acid and hydrogen ions

Pyruvate

the end product of muscle glycolysis, acting as a metabolic intermediate in the transition from muscle to meat

Lactate

a byproduct of anaerobic glycolysis produced when muscle converts to meat after slaughter

Denaturation

the process where proteins unfold and lose their native structure due to heat, acid, or physical changes

Exudative

excessive fluid loss from meat, results in PSE meat

Rigor Mortis

the post-mortem stiffening of muscle tissue, transitioning into meat, caused by a depletion od energy after death

Onset of Rigor Mortis

the beginning 2-6 hours after slaughter

Completion of Rigor Mortis

6-12 hours post=slaughter

Resolution of Rigor

24-48 hours post-slaughter

Aging

the natural, post-mortem process where enzymes break down structural muscle proteins

Conditioning

the post-slaughter process where endogenous enzyme break down muscle proteins

Calpains

calcium-dependent cysteine proteases in skeletal muscle

Multicatalytic Proteinase Complex (MCP)

2OS proteasome complex found in the cytosol and nucleus of skeletal muscle cells

Cathepsins

lysosomal proteases in muscle that degrade proteins, acting as key contributors to postmortem meat tenderization

Calpastatin

a natural protein that inhibits the activity of calpain enzymes, responsible for breaking down muscle tissue into meat

Water Binding Capacity

the ability of muscle proteins to retain inherent water during processing, handling, and cooking

Homeostasis

the post-slaughter process where muscles attempt to maintain a stable environment and energy balance despite the loss of blood circulation and oxygen

Pale, Soft, Exudative (PSE) Muscle

a major pork quality defect characterized by rapid post-mortem pH decline while meat temperature remains high

Dark, Firm, Dry (DFD) Muscle

meat quality defect caused by chronic stress or exhaustion before slaughter, resulting in high pH

Dark Cutting

beef quality defect resulting from long-term pre-slaughter stress where depleted muscle glycogen levels prevent normal lactic acid production

Myostatin Gene

acts as a negative regulator of skeletal muscle growth, controlling the size and number of muscle fibers

Halothane Gene

a genetic mutation in pigs that causes severe stress susceptibility and directly leads to poor pork production (PSE)

Alt Name: HAL-1843 mutation, RYR1 gene

Rendement Napole Gene

dominant genetic mutation causing significantly higher glycogen levels in muscle

Alt Name: Acid Meat Gene,

Callipyge Gene

a naturally occurring genetic mutation in sheep resulting in extreme, post-natal muscular hypertrophy in loin and hindquarters

Double Muscling

a mutation in the myostatin gene that inhibits the production of the myostatin protein

Sex Odor

an unpleasant odor or taste that can be detected during cooking or consumption in pork, typically derived from uncastrated male pigs

Alt Name: Boar Taint

Blood Splash

severe cosmetic defect in meat characterized by tiny blood spots or large clots within muscle tissue, caused by the rupture of small capillaries

Thaw Rigor

extreme meat toughness caused by freezing muscle before rigor mortis sets in

Cold Shortening

a severe muscle contraction occurring during pre-rigor meat

Accelerated or Pre-Rigor Processing

removing muscle from a carcass and processing it with minutes to hours after slaughter

Electrical Stimulation

post-slaughter process where a high or low-voltage electric current is applied to carcasses to induce muscle contractions