Meat Preservation and Processing Notes

Fresh Meat

• Fresh meat is chilled skeletal muscles with incorporated tissues.
• Key characteristics: color, water-holding capacity, aroma, and texture.

Stored Meat Changes

• Physical: shrinkage, swelling, color, texture changes.
• Chemical: rancidity, protein degradation.
• Microbiological: spoilage (influenced by temperature, oxygen, storage duration).

Physical Changes in Stored Meat

• Shrinkage: weight loss due to water evaporation.
  • 1.5-2.0% weight loss in the first 24 hours.
• Swelling: condensation of water vapor when meat moves from cold to warm environment.
• Color Changes: myoglobin oxidation causes duller color.
  • Bloom: appearance of carcass surface. Loss of bloom: tissues become moist, collagen swells.
• Texture Changes: granular/crumbly texture in frozen meat, rancid fat; depends on storage conditions and packaging.

Chemical Changes in Stored Meat

• Indicate protein breakdown.
• Rancidity: oxidation of fatty acids, leading to unpleasant flavor and odor.
• Protein Degradation: breakdown of proteins, affecting texture and flavor.
• pH Changes: post-mortem pH drop, affecting water-binding and texture.

Rancidity

• Oxidation of fats, producing volatile compounds (aldehydes, ketones).
• Detection: stale odor, bitter taste, dry/discolored appearance.
• Fat condition determines storage life more than muscle condition.

Protein Degradation

• Breakdown of proteins into peptides and amino acids.
• Impacts meat quality and flavor (e.g., fermented meats).

Microbiological Changes

• Spoilage: Microbial growth (bacteria, molds) causes odors, discoloration, slime.
• Pathogens: Spoilage bacteria can be pathogens.

Factors Affecting Changes

• Temperature: Lower temperatures slow changes.
• Oxygen: Promotes oxidation and rancidity.
• Storage Duration: Longer storage increases changes.
• Packaging: Protects from oxygen, moisture, and microbes.
• Type of Meat: Different meats have varying shelf lives.
• Storage Conditions: Temperature, humidity, cleanliness impact shelf life.

Preservation of Meat

• Why: To delay spoilage, extend shelf life, improve quality and economic gain
• Meat is perishable due to:
  • Nearly neutral pH
  • High moisture
  • Rich in nutrients for microbial growth

Types of Preservation

• Temperature Control (Low and High Temperatures)
• Moisture Control
• Direct Microbial Inhibition

Preservation by Moisture Control

• Drying
• Salting
• Smoking
• Intermediate Moisture Meat/Foods

Preservation by Temperature Control

• Low Temperature: Chilling, Freezing
• High Temperature: Thermal Processing

Preservation by Direct Microbial Inhibition

• Chemical
• Antibiotics
• Irradiation

Drying (Dehydration)

• Reduces moisture to prevent microbial growth.
• Methods: sun drying, mechanical drying, freeze-drying (-40°C, vacuum for 9-12 hours).
• Examples: Jerked Beef, Charque, Dried Sausages.

Curing (Salting)

• Preservation using salt as a preservative and flavoring agent.
• Reduces a_w (water activity).
• Ingredients: Sodium chloride, sodium nitrite, sodium nitrate, sugar.

Sodium Chloride (Common Salt)

1. Dehydration and osmotic pressure alteration.
2. Chloride ions action on microorganisms.
3. Slows proteolytic enzymes.

Sodium Nitrates and Nitrites

• Stabilize cured meat color and flavor.
• Inhibit Clostridium botulinum (at permitted levels: 500 ppm nitrates, 200 ppm nitrites).
• Retard rancidity.

Curing Process

• Limited to pork (ham, belly) and beef (brisket, leg).
• Temperature: 3 ± 1°C, curing time 3-4 days.

Methods of Curing

1. Dry cure: Rubbing dry ingredients on meat (e.g., bacon).
2. Pickle cure: Immersion in ingredient solution (e.g., pork shoulder).
3. Injection cure: Injecting concentrated solution (e.g., pork ham).
4. Direct addition method: Adding agents to ground meat (e.g., luncheon meat, sausage).

Common Defects in Cured Meat

1. Fiery red areas: Lack of nitrite.
2. Jelly pockets: Brine injected into connective tissue.
3. Discoloration: Bruising or blood splashing.
4. Rancidity: Yellowing of fat in frozen bacon.
5. Browning: Dehydration due to low humidity, high temperature, oxidation.
6. Greening: Excessive nitrate, bacterial contamination.

Smoking

• Used with salting and curing for flavor, aroma, and preservation.
• Smoke contains bacteriostatic wood degradation products (aldehydes, ketones, phenols).
• Smoke constituents have antioxidant properties.
• Smoke generated at ~300°C to minimize carcinogenic compounds.

Intermediate Moisture Meat

• Moisture content: 20-40%, water activity (a_w) 0.75-0.85.
• Shelf-stable at room temperature.
• Resistant to bacteriological spoilage without refrigeration.
• Example: Pastirma (5% salt, 30-35% moisture).

Chilling/Refrigeration

• Short-term storage at 0°C and 4°C.
• Slows microbial growth and enzymatic reactions.
• Rapid cooling reduces surface micro-organisms, weight loss, and discoloration.
• Air chilling is most common.
• Fresh meat stays in good condition for 5-7 days at 4±1°C.

Freezing

• Longer duration preservation; stops microbial growth, retards enzymes.
• Wrap meat in packaging film to avoid freezer burn (surface dehydration).
• Product is frozen when center reaches -12°C or less.

Freezing Speed

• Affects ice crystal size; faster freezing results in smaller crystals.
• Good results: 2 to 5 cm/h.
• Slow freezing: below 1 cm/h; quick freezing: above 5 cm/h.
• Quick freezing: Many small ice crystals, mainly formed within the muscle cells, and reduces water migration and separation of solution

Thermal Processing

• Prolonged shelf-life by reducing/inactivating micro-organisms via heating.
• Sealed in container (can, jar, pouch) and subjected to defined temperature/time.

Temperature Regimes

• Pasteurization: Moderate heating (58°C to 75°C), kills most micro-organisms.
• Sterilization: Severe heating (above 100°C), kills all spoilage micro-organisms.

Canning

• Preservation by thermal sterilization in hermetically sealed containers.
• Maintains sensory attributes with shelf life of at least 2 years.

Canning Steps

1. Preparation of meat and gravy.
2. Precooking: At 70°C for 15 minutes to cause shrinkage and reduce microbial load.
3. Filling: Cans filled manually or mechanically with proper headspace.
4. Exhausting: Air removal from container before closing.
5. Seaming: Done by double seamer machine.
6. Retorting/Thermal Processing: High temperature under pressure for commercial sterility.
7. Cooling: Fast cooling to 30-40°C.
8. Storage: Cool, dry place at ~20°C.

Antibiotics

• Inhibit bacterial growth but raise concerns about resistance.
• Overuse contributes to antibiotic-resistant bacteria.

Antibiotics Use in Meat Preservation

• Direct Application: Delay spoilage in poultry and fish.
• Animal Feed: Prevent disease or promote growth.
• Injections: Treat or prevent infections before slaughter.

Types of Antibiotics Used

• Tetracyclines: Chlortetracycline (CTC) and oxytetracycline (OTC).
• Penicillin: Sporicidal effect.
• Streptomycin: Effective against bacterial soft rot in vegetables, but not high-protein foods.

Irradiation

• Uses radiation to kill harmful bacteria/parasites.
• Extends shelf life & enhances safety.

How Irradiation Works

• Ionizing Radiation: Gamma rays or X-rays damage DNA of microorganisms.
• Cold Sterilization: Destruction of microorganisms without significant temperature increase.
• Doses of 50-100 Krad enhance shelf-life of fresh meat by 19 days.
• Non-ionizing Radiation: Ultraviolet radiations for surface sterilization.

Chemical Preservatives

• Prevent microbial growth in foods.
• Organic Acids: Citric, propionic, benzoic, sorbic acids act as mold inhibitors.
• Acetic, lactic acids prevent bacterial growth.

Nitrates and Nitrites

• Inhibit Clostridium botulinum growth (botulism).
• Contribute to pink color and flavor of cured meats.

Meat Processing

• Extends shelf-life, creates convenience.
• Includes preparation, cutting, curing, smoking, seasoning, refrigeration, and freezing.
• Goal: Improve taste, extend shelf life, prepare for various products by:
  • Reducing enzyme activity
  • Retarding oxidation
  • Preventing spoilage

Purpose of Meat Processing

• Improve taste and flavor.
• Extend shelf life.
• Customize products.
• Add value and improve marketability.

Flow Diagram for Fresh Meat Production

• Pre-slaughter care → Stunning→ Sticking → Skinning/Dehairing → Evisceration→ Washing→ Chilling → Cutting/Deboning → Packaging → Freezing/Delivery

Primary Meat Processing Steps

1. Rest and Fasting: Resting for 12-24 hours, fasting for 12-24 hours reduces bacterial load and eases dehiding.
2. Ante Mortem Inspection: Vet checks for communicable diseases within 24 hours of slaughter.
3. Stunning: Induces insensibility for humane slaughter.
4. Sticking and Bleeding: Incision severs carotid arteries and jugular veins to cause death through exsanguination. Bleeding for a minimum of 6 minutes.
5. Dressing: Carcasses are dressed, and excess fat, viscera, and offals are separated.
6. Deheading: Head and feet are removed; head, skin, feet, and tail left attached in pigs
7. Dehiding: Hide/skin is removed; in pigs and poultry, skin is retained.
8. Evisceration: Pelvic, abdominal, and thoracic cavities are opened to remove internal organs.
9. Post Mortem Inspection: Carcass and organs inspected; pathological conditions lead to condemnation.
10. Carcass Washing and Decontamination: Pressurized water and decontaminants (chlorinated water, lactic acid) used.
11. Chilling: Reduce surface temperature to inhibit bacteria growth.
12. Fabrication: Cutting the carcass into wholesale and retail cuts.
13. Ageing: Holding unprocessed meat above freezing to increase tenderness and flavor.
14. Packaging: Prevents contamination, color deterioration, moisture loss, odor pickup, rancidity/easier transport
15. Storage: Chilling, freezing, plate freezing, blast freezing and cryogenic freezing

Friesla Meat Processing System Steps

1. STUN & BLEED
2. HARVEST: hide removal, evisceration (organ removal), trimming
3. COOLING/DRAWDOWN: The carcass is moved on the meat rail from the Harvest Room into the Carcass Drawdown Cooler
4. AGING: livestock like hogs, sheep, and goats between 1-3 days and age beef between 7-14 days
5. CUTTING/FABRICATION: carcass halves (or sides) into quarters, then primals and/or subprimals, and ground product.
6. READY-TO-EAT (RTE) PRODUCTS
7. PACKAGING
8. FROZEN STORAGE

Animal Byproducts

• Only one-third of animals is harvested as meat.
• Byproducts represent 66.0%, 52.0%, and 68.0% of live weight for cattle, pigs, and sheep, respectively.
• Byproducts are meet environmental regulations and recover useful nutrients/rich products.
• Edible: Variety meats or specialty meats, organs, etc. Utilization depends on religious, economic status, and local customs.
• Inedible: Downgraded edible byproducts used as pet food, animal feed, pharmaceuticals, and cosmetics.

Primary Meat Processing Steps

1. Particle Size Reduction (Comminution)
   • Sectioning meat using knife
   • Chunking meat with grinder plate and dicer.
   • Slicing using meat slicer with revolving blade
   • Flaking Rotating impeller forces meat through flaking heads openings.
   • Mincing Feed boneless meat chunks onto a rotating spiral shaft or a pump type system
   • Chopping Meat done in bowl chopper or silent cutter
2. Emulsification
   • Mixing meat and water with salt forms a water-in-fat emulsion with solubilized muscle protein as emulsifier.
3. Meat Extension
   • Incorporating non-meat food items(fillers, binders, emulsifiers, stabilibilizers) to reduce costs
4. Pre-Blending
   • Mixing curing ingredients with ground meat.
5. Hot Processing
   • Processing within 1-2 hours after slaughter increases cooking yield reduces processing time
6. Cooking/Heat Processing
   • Improves eating/keeping qualities, palatability, and storage life via:
     • Protein denaturation
     • Flavor intensification
     • Microorganism reduction
     • Texture modification

Machineries for meat processing

• Slicer-Achieved by a revolving blade
• Mincer-Reducing meat into different particle sizes with grinder plates of different hole sizes (3, 5, 8 & 13 mm
• Bowl chopper-Chopping of meat is done with bowl chopper consisting of sharp multiple blades with revolving bowl.
• Tumbler fragmentation of meat fibers through the pressure
• Mixer/Massager Mixing/massager
• Brine injectorInjecting brine
• Sausage fillerStiffing meat emulsion.
• Automatic patty making and meat ball forming machines
• Blade tenderizer Pressing meat cuts set of multiple blades

Machineries for cooking of meat

• Flame cookers -indirect cooking of meat
• Steam cookers -Moist cooking equipment
• Hot air ovens-Dry cooking or broiling
• Microwave ovens-Heating of product
• Smoke ovens-application of smoke by burning if hard wodd
• Deep fat fryersUsed for frying of meat enrobed meat products.
• Griller Method of cooking tender/marinated meat cuts
• Barbequing Method of cooking meat marinted in barbeque saude
• Tandoor oven Specifically designed for cooking meat cuts over coal

Meat product types

• Canned
• Cooked/ Cured
  • Meats
• Frozen meats Cooked or raw
  • Cutlets or burger patties
• Dry-preserved
  • Low water activity
  • meats
  • Beef jerky
• Cured meats
  • Salt, nitrite and other adjuncts added
  • Hams, Bacon
• Sausages Comminuted or emulsified
  • Frankfurter, Salami, Pepperoni, Hot dogs
• Dinner meats
  • Precooked
  • Products; pumped products
• Luncheon meats
  • Fully cooked and ready to
  • Eat; restructured meats
  • Sliced ham, Bologna and Salami

Personnel Hygiene

• Maintain high standards of personal cleanliness.
• Avoid potential hazards.
• Employees who suffer from infection diseases and any cuts or wounds are not able to work
• Personnel must be vaccinated
• Personnel must avoid eating, smoking, spitting, chewing, sneezing or coughing over any food
• Personnel must avoid wearing false nails or loose jewelry that might fall into food and also avoid touching their face or hair.
• Personnel must maintain a high degree of personal cleanliness. They shall be provided with adequate and suitable clean protective clothing, head covering, face mask, gloves and foot wear.
  Equipment and Facility Design
• Sanitation: Safeguarding health through cleanliness.
• Hygiene: Practices to keep areas clean to prevent illness.
• Cleaning: Physical removal of soil and debris.
• Sanitizing: Reducing microorganisms on a surface to safe levels.

Cleaning and Santizing Procedure

1. Remove all exposed products
2. Dry clean/sweep area
3. Wet area to be cleaned
4. Clean and scrub area
5. Rinse
6. Sanitize
7. Air dry/store properly

Sanitation and maintenance practices

• Equitempt will be properly and carefullycleaned
• Proper sewage cleaning and water disposal
• Toilet and hand-washing facilities available
• Building well maintained to prevent damage
• Avoid light above meat processing
• Staff wears protective equipment
• Temperture of water be optima during ahdn wash