Meat Chemistry and Functionality Notes

Meat Chemistry and Its Relationship to Functionality

Definition: Ability to perform a task or function in food materials during processing, affecting final product quality and stability.
Known as Technological Quality; varies by product suitability.
Functional properties depend on interactions between food components (proteins, lipids, water) and environmental factors.
Not the same as properties of "functional" foods.

Myofibrillar Proteins (Salt-soluble)
- Main Proteins: Myosin, Actin, Tropomyosin, Troponin, Titin, Nebulin.
- Responsible for muscle contraction and thus very important in meat processing.
- Water-Holding Capacity (WHC) and binding properties (70-80%).
Sarcoplasmic Proteins (Water-soluble)
- Examples: Myoglobin (O2 storage), enzymes, and other small proteins.
Stromal (Connective Tissue) Proteins (Insoluble)
- Examples: Collagen, Elastin, Proteoglycans, Glycoproteins.
- Provide structural network maintaining muscle order.

Composition: ~60% of total muscle protein.
Functions: Nutritional value, texture, water-holding capacity.
Require ionic strength > 0.3 for solubility in salt, primarily at 4-5% brine.
Myosin is particularly important due to its structure and amino acid composition.

Content: 10-15% total muscle protein.
Composition: Primarily collagen (20-30% of total body protein in mammals), essential for the structural integrity of tissue.
Collagen varies with muscle functions and animal age; older animals yield tougher collagens due to increased crosslinking.
Excessive collagen can impede product texture and WHC, thus keeping its content under 15-25% in processed meat products is important.

Comprise 29-30% of total muscle protein and about 20% of binding capability.
Involved in metabolic activities, including enzyme actions (e.g., calpains for tenderization) and color (myoglobin affects meat color variations).

Determining Factors: Myoglobin concentration, oxidation state of heme iron, ligand presence at heme's 6th coordination site, and structural state of globin.
Types: Deoxymyoglobin (purple-red), Oxymyoglobin (bright red), Metmyoglobin (brown).
Environmental Factors: pH, temperature, and partial oxygen pressure greatly influence pigment stability and freshness.

Water Binding/Moisture Retention: Influenced by ionic strength, pH, and protein conformation.
Protein Solubility and Extractability: Affects other properties like emulsification.
Emulsion/Batter Forming Ability: Critical for binding fat and water in meat applications.
Gelation: Development of a stable, semisolid structure upon heating, important for texture and moisture retention.

Functions: Contribute to flavor, juiciness, and texture.
Lipid types include triglycerides, sterols, and phospholipids.
Rancidity: Deterioration leads to off-odors and flavors.
- Types of Rancidity: Oxidative and hydrolytic.
- Oxidative: Involves unsaturated fatty acids, increased by oxygen and heat exposure.

Water Holding Capacity (WHC): Ability of meat to retain water; depends on protein interactions and external forces (grinding, heating).
Forms of Water: Free, bound, and immobilized water; bound being crucial for texture.
Water Activity (aw): A measure of water availability for microbial growth and chemical reactions, crucial for food preservation.

Colder temperatures improve protein solubility, reduce fat smearing, and control microbial growth.
Importance of using cold brines for optimal protein extraction and hydration.

Enhance quality through proper management of protein functionality, lipid integrity, and water activity.
Continuous monitoring and adjustment of processing conditions (such as pH and ionic strength) is critical for achieving desired product characteristics.