Selection of Quality Meat for Processing – Comprehensive Study Notes

Overview

  • Focus: selection of quality meat, principles of processing, preservation techniques, non-meat ingredients, curing, product classifications, and casings.
  • Guiding ideas:
    • “Meat” means different things to different sectors, but in this lecture it generally refers to edible skeletal muscle and associated tissue.
    • “Quality” = degree of product excellence (freshness, safety, sensory traits, suitability for processing).

Core Processing Principles

  • Connective-tissue integrity, moisture, fat, and cohesive forces ultimately dictate texture, yield, shelf life, and eating quality.
  • Muscle biochemistry governs water binding, color stability, and flavour development.

Moisture Retention (Lean-Meat Property)

  • Water-Holding Capacity (WHC): ability to retain intracellular water already present.
  • Water-Binding Capacity (WBC): ability to bind extra water added during formulation.
  • Cooking loss = total \text{water} + \text{fat} + \text{jelly} expelled during heat processing.
  • Meat binding = adhesion of meat pieces after cooking (vital for formed products).
  • Typical composition of lean muscle (≈75\% water):
    • Intracellular water in fibres =45\%
    • Extracellular space =19\%
    • Fibrils =11\%
    • Total water =75\%; proteins =18\%; other substances =7\%.
  • Fatty tissue contains ≈10\% water confined to connective walls around lipid cells; affects juiciness and flavour (see strip-loin photo: L, M, H intramuscular fat).

Causes of Meat Deterioration

  • Biological (≈99.9\% of all biological spoilage): bacteria, molds, yeasts, parasites, insects, rodents.
  • Chemical: oxidative rancidity of lipids; oxidation of myoglobin → metmyoglobin (brown color after several days in air) Fe^{2+}\to Fe^{3+}.
  • Physical: dehydration, drip loss, enzymatic autolysis.
  • Effective preservation must: (1) start with low microbial load; (2) be practical, economical, palatable; (3) counteract deterioration forces.

Preservation Approaches

  1. Cold Storage (Chilling 0–4^\circ\text{C}, Freezing <-3^\circ\text{C})
    • Slow freezing (>30\text{ min}); Quick freezing (<30\text{ min} via blast, deep, cryogenic, spray). Quick freezing = less drip, better WHC, flavour retention.
    • Shelf-life depends on initial microbes, cut size, and storage temperature.
  2. Drying / Dehydration
    • Reduce water activity by sun-drying or mechanical dehydrators; water can also be bound with solutes.
  3. Salting
    • Osmosis draws water out → plasmolysis; Cl^- lowers O$2$ solubility, sensitises microbes to CO$2$, slows rancidity, enzyme actions.
  4. Curing (salt + sugar + nitrite/nitrate ± adjuncts)
    • Historically preservative; now primarily for flavour and color.
  5. Smoking
    • Hardwood smoke supplies phenols, formaldehyde, creosote film → antimicrobial, insect repellant, moisture barrier; combined heat further dehydrates.
  6. Canning
    • Thermal inactivation >110^\circ\text{C} (sterilisation) or pasteurisation.
    • Shelf-stable without refrigeration after sterilisation.

Non-Meat Ingredients

Salt (NaCl)

  • Primary curing agent; recommended 2.5–3.0\% of meat weight.
  • Extracts salt-soluble myofibrillar protein (myosin) → binding matrix.
  • Types: solar/coarse, fine “Pangasinan”, refined industrial (least impurities).

Sugar

  • Secondary curing agent; masks salt astringency, feeds lactic bacteria (pH↓) → characteristic flavour; can shorten shelf life via yeast/mold growth.

Nitrate & Nitrite (food-grade)

  • Preserve and inhibit Clostridium\,botulinum; supply NO for cured pink color.
  • Nitrite burn possible >600\text{ ppm}; legal residue limit \le 156\text{ ppm}.
  • Also flavour impact, antioxidant.

Ascorbates / Erythorbates

  • Speed curing: reduce myoglobin and convert nitrite → NO.
  • Recommended 500\text{ mg}/\text{kg}.

Phosphates (adjuncts)

  • Raise pH, increase WHC, yield, emulsion stability; limit \le1\text{ tsp} in \tfrac14 cup water per 1\text{ kg} meat (≈3\text{ g/}60\text{ g} water).
  • Must dissolve before brine; high levels → “soapy” taste, surface “whiskers.”

Coloring Agents

  • Needed because processing alters appearance.
  • Replacements for FD&C Red #3: Allura Red (#40) orange-red; Carmine/Cochineal magenta- or purple-red; Red-beet concentrate purple-red; Annatto yellow-orange; Paprika deep red-brown (may fade in sunlight).

Spices

  • FDA: aromatic vegetable substances for seasoning; store sealed, cool, dry.

Monosodium Glutamate (MSG)

  • Flavour enhancer; maximum 0.2\% or 2.0\text{ g}/\text{kg} (≈\tfrac12 tsp). Excess may cause “Chinese restaurant syndrome.”

Functional Proteins & Carbohydrates

  • Binders (protein >70\%): sodium caseinate, soy isolate/concentrate, wheat gluten → WHC, emulsification.
  • Fillers: cereal flours, starches; absorb water but weak emulsifiers.
  • Extenders: bulk plant proteins; modify cost & texture.

Casings

  • Purpose: containment, shape retention, moisture/smoke regulation.

Natural

  • Hog & ruminant intestines; used for fresh, frankfurters; cleaned, salted/dried.

Artificial

  • Cellulose, collagen, plastic, fibrous.
  • Uniform diameter, selectable permeability, strong.
  • Cellulose casings (1.5–15 cm Ø) contain internal dye; do NOT pre-soak.
  • Fibrous casings: cellulose‐reinforced for extra toughness.

Curing Techniques

  • Goal: shelf-life ↑, colour, flavour.

Dry Cure

  • Dry rub; extra on boned areas.

Sweet Pickle Cure

  • Ingredients dissolved in water; salometer 70^\circ; ≈420\text{ mL} brine per 1\text{ kg} meat; product submerged.

Combination (Injection)

  • Accelerated: inject 8–10\% brine by weight then dry-rub or immerse; hold at 2–4^\circ\text{C}, turn every other day.

Classification of Processed Meat Products

Non-Comminuted (Whole-muscle)

  • Intact cuts, boned, cured/seasoned/smoked; e.g. ham, bacon.
    • Ham: cured, sometimes dried, cooked, molded; sold whole/sliced.
    • Bacon: cured & smoked belly or loin (pork or beef); shelf life ≤7 days refrigerated; cook before eating.

Comminuted Products

  • Made from pieces, chips, ground meat.

Sausages (Major Categories)

  1. Fresh – uncured; must be cooked.
  2. Uncooked – mildly cured; cook before serving.
  3. Uncooked-Smoked – mild cure + smoke; cook before serving.
  4. Cooked-Smoked – most popular; often 60\% beef + 40\% pork.
  5. Dry / Semi-dry – lose 25–40\% or 8–15\% weight respectively; fermented variants add lactobacilli for acid flavour and safety.

Cooked Meat Specialties

  • Chopped mixtures in loaf form; luncheon meat, jellied products.
    • Luncheon meat: coarse particles bound by fine paste; usually commercially sterile in cans (common Philippine sizes: 307\times113, 211\times300, 300\times400).
    • Meat loaf (US styles): ranges from pure emulsion to mixed ground or gelatin-bound precooked pieces; cooked by steaming, baking, or water.

Canned Meats

  • Pasteurised (refrigerated) vs Sterilised (>110^\circ\text{C}, shelf-stable).

Other Products

  • Any processed items from chunks, slices, pieces not in above categories.

Practical / Ethical / Safety Implications

  • Microbial safety (especially C.\,botulinum) underpins every additive limit (nitrite \le156 ppm).
  • Consumer health: avoid excessive phosphates, MSG, nitrites; monitor allergen declarations (soy, gluten, milk proteins).
  • Environmental & cultural aspects: natural vs artificial colors; sourcing natural casings from by-products aligns with waste minimisation.

Key Numbers & Formulas

  • Muscle water ≈ 75\%; fat tissue water ≈ 10\%.
  • Chilling 0–4^\circ\text{C}; Freezing below -3^\circ\text{C}.
  • Quick-freeze threshold <30\text{ min}.
  • Salt usage 2.5–3.0\% of total weight.
  • Nitrite residual limit \le156\text{ ppm}; burn occurs >600\text{ ppm}.
  • Ascorbate 500\text{ mg}/\text{kg}; MSG 0.20\%; Phosphate 3\text{ g}/60\text{ g}\,\text{water} per 1\text{ kg} meat.
  • Sweet pickle cure: salometer 70^\circ; brine volume 420\text{ mL}/\text{kg} meat.
  • Injection cure rate 8–10\% of meat weight.
  • Dry sausage weight loss 25–40\%; semi-dry 8–15\%.

References

  • Ranken, M.D. (2000) Handbook of Meat Product Technology. Blackwell Science.
  • Meat Processing Committee (2011) Philippines Recommends for Meat Processing, PR-76-C/11.