Meat Technology | Animal Husbandry & Veterinary Science Optional for UPSC PDF Download

Meat Technology

Physical and Chemical Characteristics of Meat

• Physical Characteristics of Meat:
  • Meat's physical attributes vary across animal species and ages.
  • Beef:
    • In young bulls, the flesh appears light red initially but darkens over time due to testosterone secretion, becoming coarser with less intramuscular fat.
    • Old bulls exhibit very dark, dried meat surfaces.
    • Bullock meat ranges from light red to dark red, displaying distinct marbling. Young cows and bullocks have white or whitish-yellow firm fat, while older cows tend to have yellower, looser fat.
  • Veal:
    • Meat from newborn calves is often pale and watery, with jelly-like fat consistency. However, in milk-fed calves, the fat quickly turns white and firmer.

Reference: Brilliant Tutorials - IAS (M)/AH/XI - 26

Understanding Different Types of Meat

• Mutton

  Mutton is reddish in color with firm fibers and minimal intermixing of fat. Fat deposits can be found between muscles in well-nourished animals.

• Goat Flesh

  Resembles mutton but has abundant kidney fat, even if subcutaneous fat is sparse. The distinct goat odor transfers from the skin to the carcass during dressing.

• Pork

  Pork color varies based on factors like age, nutrition, and body part. It is the least firm among food animals, with a range of colors from whitish grey to deep red.

• Horse

  Horse flesh is dark red or bluish post-cutting, with a unique sweet and repulsive odor. Connective tissue is well-developed due to muscle exercise, with fat resembling cow beef fat.

Chemical Composition of Meat

• Proteins

  Proteins are vital muscle constituents, comprising myofibrillar, sarcoplasmic, and connective tissue proteins. Myofibrillar proteins like myosin and actin provide muscle rigidity.

• Lipids

  Meat lipids mainly consist of triglycerides, fats, and oils, along with phospholipids and fatty acids. Horse flesh has high intramuscular fat content compared to other species.

Carbohydrates in Meat

• Glycogen is the primary carbohydrate found in meat, known as animal starch.
• Most glycogen is converted into lactic acid through glycolysis post-slaughter, leading to a drop in meat pH from around 7.2 to 5.5.
• The rate of pH decline is influenced by factors like initial glycogen levels, genetic factors, animal species, muscle type, feeding habits, and any acid stress before slaughter.
• Low glycogen levels at the time of death result in a final pH above 5.5, while high levels lead to a lower pH.
• In some cases, pig muscles can undergo pale soft exudative changes (PSE) due to the rapid accumulation of lactic acid, causing a swift drop in pH while the meat temperature remains high.
• Meat pH impacts water retention, color development during curing, and bacterial growth in meat.
• Glycogen is also present in the liver, particularly abundant in horse meat and fetuses, with relatively stable levels compared to fat content.

Non-Protein Nitrogen in Meat

• Non-protein nitrogen in meat primarily consists of free amino acids, creatine, nucleotides, monophosphate, and carnosine.
• Free amino acids and nucleotides notably contribute to the flavor of meat upon cooking.

Meat Extractives

• Meat extractives are key components of commercial extracts derived from concentrated liquors where beef muscle and offal parts are soaked and cooked.

Inorganic Minerals in Meat

• The inorganic minerals or ash content in muscle make up slightly less than 1% of the total composition.
• Major elements include sulfur, potassium, phosphorus, sodium, chlorine, magnesium, calcium, iron, and zinc.

Vitamins in Meat

• Vitamins in meat are primarily water-soluble B vitamins like thiamine (B2), riboflavin (B2), niacin, pyridoxine (B6), pantothenic acid, biotin, folic acid, and cyanocobalamin (B12), along with vitamin C.
• Pork contains approximately ten times more thiamine than beef and lamb, while beef has significantly higher folic acid content than pork or lamb.
• Liver is a rich source of B vitamins, especially thiamine.
• Meat Pigments:
  • Myoglobin and Hemoglobin: Constituents in meat responsible for its redness, with varying percentages across different types of meat. For instance, pork has the least (0.06 to 0.40 per cent), while poultry has 0.02 to 0.18 per cent.
  • Gender and Muscle Activity: Myoglobin content is higher in males and in muscles that are frequently used, such as the heart and diaphragm.
• Reducing Bodies in Meat:
  • Enzyme Action: Presence of enzymes with oxidizing properties, particularly evident in meat affected by icterus, a condition causing yellowing of tissues due to bilirubin.
  • Discoloration: The yellow coloration from icterus may disappear if the affected meat is stored for 24 hours.
• Meat Emulsions:
  • Water Holding Capacity: Factors like pH levels and postmortem glycolysis influence the ability of muscle proteins to retain water. Rapid cooling before rigor mortis can enhance water holding capacity.
  • Salt Function: Salt aids in loosening myofibrillar proteins, enhancing their emulsifying ability, especially near the iso-electric point.
  • Protein Behavior: Myosin's surface activity at interfaces, effects of proteolytic enzyme action, and limitations on fat holding capacity in protein water gel.
  • Stability Factors: Influence of cooked rind, heating process, coagulation network, fat coalescence, and fat melting ranges on emulsion stability.

Methods of Preservation of Meat

• Purpose of Food Preservation: The main aim of food preservation is to prevent food spoilage, primarily caused by microorganisms that thrive under specific environmental conditions.
• Principle of Preservation: All preservation methods aim to create unfavorable conditions for microbial growth or survival by using extreme heat or cold, removing water and oxygen, increasing saltiness, or raising acidity levels.
• Methods of Meat Preservation:
  • Drying: Drying, while not widely used commercially today, plays a vital role in removing water for microbial growth prevention. Examples include jerked beef in South America and pemmican in North America.
  • Concerns with Biltong: Biltong from South Africa, made from various meats, can pose risks such as contamination with Salmonella organisms, which may resist curing and drying processes.
  • Parasitic Cysts: Salt concentration is crucial for destroying parasitic cysts like cysticerci, ensuring safety by maintaining specific salt levels for a required duration.
  • Curing: Curing, suitable for fatty meats like pork, involves pickling various meats, with certain meats like lean beef, veal, or mutton being less suitable for this method due to texture changes.
• Salt as a Preserving Material:
  • Salt serves as a preserving agent on a large scale, with its effectiveness comparable to that of sugar in extracting water from food products.
  • The osmotic pressure created by salt or sugar solutions inhibits bacterial growth by depriving them of the necessary water content.
  • Halophilic bacteria, which thrive in salty environments, are not hindered by the presence of salt.
• Comparison: Salted vs. Cured Meats:
  • Salted meats like beef and pork involve the slow inward distribution of dry salt throughout the meat, leading to moisture removal.
  • Cured meats such as bacon, ham, and corned beef entail the addition of salt, nitrate/nitrite, or nitric oxide, transforming meat pigments and enhancing preservation.
• Smoking for Preservation:
  • Smoking is a preservation technique commonly used for bacon to maintain color and flavor.
  • The process involves dusting bacon with wood particles before smoking in specially designed rooms emitting cool smoke.
  • Formaldehyde in wood smoke acts as a bacteriostatic and bactericidal agent, reducing surface bacterial populations.
• Canning Method:
  • Food preservation through canning relies on creating unfavorable conditions for spoilage organisms or destroying them through heat.
  • In commercial canning, foods in sealed containers undergo heat treatment to eliminate spoilage organisms and prevent recontamination.
  • Aseptic canning, a newer method, sterilizes food at high temperatures for short durations before sealing in sterilized cans to enhance flavor and vitamin retention.
  • Aluminum cans are increasingly used due to their lightness and resistance to rust, although efforts are ongoing to develop stronger alloys for better durability.

Thermal Processing in Food Preservation

• Introduction to Flexible Pouches

  Flexible pouches made from thermoplastic and aluminum foil are popular in Japan, Europe, and the United States. These pouches require sterilization due to their inability to withstand high internal pressures during processing.

• Flame Sterilization for Cans

  For open or sanitary cans, flame sterilization is utilized, such as the Tarax flame sterilizer from Australia. This method is cost-effective and efficient for products with liquid content.

• Emerging Technologies

  Future thermal processing methods may include the use of microwave energy, hydrostatic sterilizers using high-efficiency steam, and fluidized-bed systems.

• Understanding Thermal Death-Rate Curve

  When bacteria are exposed to heat, their survival follows a logarithmic curve against heating time at a constant temperature. The D value represents the time needed to reduce surviving bacteria to 10% of their original count.

• Ensuring Sterility

  Total sterility is unattainable in thermal processing, with effectiveness measured against the heat resistance of Clostridium botulinum spores. Canning operations aim to reduce Cl. botulinum spores by a factor of 10^12.

• Adapting Heat Treatments

  Foods with a pH below 4.5, where Cl. botulinum spores do not grow, may undergo gentler heat treatments based on their acidity levels.

Summary of Irradiation and Food Packaging Information

• Overview of Irradiation

  Irradiation involves using electromagnetic radiation to inhibit microorganism growth in foods. While it has potential for food sterilization, concerns include impacts on nutritional value, carcinogen production, and induced radioactivity.

• Current Status in the UK

  In the UK, the use of ionizing radiation for food sterilization is mostly prohibited, except for specific scientific investigations. High costs of refrigeration and canning drive the search for alternative food preservation methods.

• Challenges of High-Frequency Radiation

  High-frequency radiation faces difficulties in controlling heat production. While it may aid in defrosting and blanching, practical applications are limited.

• Meat and Meat Products Packaging

  Prepackaged frozen meat is popular for its convenience. Specialized packaging is crucial due to prolonged storage needs below freezing points that lead to desiccation and fat oxidation. Materials like 'Sarlyn' are emerging for tight wrapping without puncturing, preserving meat color and quality.

Meat Preservation and Processing

Glazing and Wrapping Techniques

• Glazing with water protects meat from drying out and oxidation.
• In the U.S.A., using edible coatings like acetylated monoglycerates on frozen cuts is recommended.
• Wrapping materials like aluminium foil, polyethylene, and polyvinyl iodine chloride help retain moisture, flavor, and odor in cooked meat.
• Packing meat in nitrogen or vacuum can enhance palatability.

Preservation Methods

• Thermal processing for meat preservation dates back to the 19th century, evolving into the canning industry.
• Metal cans are commonly used for canned meats in the UK, with interior lacquering to prevent discoloration.
• Heat sterilizable flexible bags, made from multiple laminates, reduce processing time and maintain product quality.
• The retort pouch expedites meal preparation and serving.

Meat Products and Formulations

• Meat products are created by converting raw meat into easily digestible forms suitable for consumption.
• Raw meat is emulsified through size reduction, shaping, and heating to denaturation temperature, resulting in ready-to-eat products.
• The process ensures the removal of connective tissue, muscle fibers, cartilage, bone fragments, and collagen.
• Reformed meat portions have excellent mastication and digestion qualities, ideal for various food preparations including infant food.

Sausage Room Products Overview

• Sausage: The process of stuffing salted chopped meat seasoned with spices into animal casings.
• Varieties of Sausages:
• 
  
  • Frankfurter: Originating from Germany.
  • Bologna: Associated with Italy.
• Classes of Sausages:
• 
  
  • Fresh Sausages: Not cured or smoked, prepared with water for ingredient chopping.
  • Pork Sausage: Made with chopped or ground pork and seasonings.
  • Fresh Thuringer: Primarily pork with added veal.
  • Cooked Sausage: Cooked in water vats, steam chambers, or smoke houses.
  • Frankfurters and Wieners: Made with various meats and by-products, with restrictions on additional ingredients.
  • Bologna: Available in long, large, and round varieties.
• Patty-Type Products:
• 
  
  • Hamburger Patty: Contains less than 30% fat, popular in the American diet.
  • Liver Patties Preparation: Involves frozen cow livers ground below 0°F, with the option to add other products for variety.
• Processed Patty Products:
• 
  
  • Curing Process.
  • Irradiated Beef Patties: Beef mixture cooked to specific temperatures for sterilization and enzyme inactivation.

In the realm of sausage room products, a diverse array of sausages exists, each with unique characteristics and origins. Sausages encompass a broad category of food items that involve stuffing salted chopped meat seasoned with spices into casings made from animal intestines. Among the notable types are the Frankfurter, synonymous with Germany, and the renowned Bologna sausage hailing from Italy.Within the classification of sausages, distinct classes emerge, each defined by its preparation method and ingredients. Fresh sausages, for instance, are not cured or smoked and utilize water solely for facilitating the chopping of ingredients. Pork sausage, another prevalent category, consists of chopped or ground pork combined with various flavorings. The Fresh Thuringer sausage, predominantly pork-based with added veal, stands as a testament to the diversity within sausage offerings.Further delineations include cooked sausages, which undergo cooking in different environments like water vats, steam chambers, or smoke houses. Frankfurters and wieners, encompassing a wide variety of meats and by-products, adhere to specific ingredient limitations to maintain product quality. Bologna sausages, available in long, large, and round forms, contribute to the rich tapestry of sausage varieties.Transitioning to patty-type products, the hamburger patty emerges as a staple in the American diet, characterized by its low-fat content. Liver patties, another notable product, involve the preparation of frozen cow livers ground at sub-zero temperatures, providing a foundation for customizable patties by incorporating compatible comminuted products.In the domain of processed patty products, a meticulous curing process ensures product quality and safety. Noteworthy among these processed items are irradiated beef patties, where a specific cooking regimen is employed to sterilize the beef mixture and deactivate proteolytic enzymes, safeguarding both flavor and shelf life.

Processed Meat Products

• Bacon Production

  Bacon is made from pork bellies. It involves immersing bacon bellies in a strong brine with essential curing salts like alkaline metal nitrites. Dry salts are rubbed on the bacon belly, and the meat is left exposed to air for several weeks.

• Ham Products

  Hams are typically processed before consumption, often smoked, boneless, or canned.
  • Canned Hath: Produced through canning.
  • Smoked Ham: Created by hanging in a smoke-filled environment for hours.
  • Boned Ham

• Beef Products

  • Corned Beef

    Corning is the process of beef preservation using salt.

  • Pastrami

    A well-liked processed beef cut.
  • Dried Beef: Prepared using lean cattle's round muscle.
  • Miscellaneous Beef Items

• Various Novel Products

  • Filled and Formed Products

    Filled Meat Loaf: A meat and cheese combination where the cheese is entirely surrounded by the meat.
  • Uniform Beef Loaf: Involves long periods of drying and curing.