meats - exam 2

By products responsibility

• By-products in the livestock industry are often time responsible for the profitability of operating packing plants.

• A ball-park figure for the contribution of by-products to the value of livestock would be 10% (depending on the species).

Relationship between live weight and carcass components and by product yields

• Grade: Choice for steer, Choice for lamb, U.S. #1 pork

• Live weight

• Dressed carcass

  • 1,000 lb live weight steer won’t yield 1,000 lb in cuts

• Retail cuts, Hide or pelt, Edible fats, Variety meats, Blood

• Inedible fats, bone, and meat scraps

• Unaccounted items (stomach contents, shrink, etc)

USDA By product Drop Value (Steer)

Item is found typically lbs * price = value, except steer/heifer hide (per piece)

• Steer/heifer hide, butt branded/piece

• Tallow, edible

• Tallow, packer bleachable

  • Most valued, bio diesel

• Tongues, Swiss No. 1, export

• Cheek meat, trimmed

• Head meat

• Oxtail, selected

• Hearts, regular, bone out

• Lips, unscalded

  • Hot links

USDA By product Drop Value (Steer) Pt 2

• Livers, selected, export

• Tripe, scalded, edible

  • Rumen, in menudo

• Tripe, honeycomb bleached

  • Reticulum, in menudo

• Lungs, inedible

  • Pet food

• Melts

  • Spleen

• Meat & bone meal, 50% bulk/ton

• Blood meal 85% bulk/ton

Typical slaughter steer weighs

1,400 lbs

Examples of edible meat by-products

• Liver: Variety meat, export market to Egypt

• Heart, kidneys, spleen (melt): Variety meat

• Sweetbreads: Variety meat, export market to Mexico

• Tongue: Variety meat, export market to Japan

• Oxtails: Variety meat, seasonal market for soups

• Cheek and head trimmings: Sausage ingredient, Mexican barbacoa

• Beef extract: Soups and bouillon

Examples of edible meat by-products Pt 2

• Blood: Sausage component

• Stomach

  • Suckling calves : Rennet for cheesemaking

  • Pork: Sausage container, ingredient

  • Beef (reticulin and rumen: Honeycomb tripe, tripe, and sausage ingredient

• Bones: Gelatin for confectioneries, ice cream, and jellied food products

Examples of edible meat by-products Pt 3

• Fats

  • Cattle, calves, lambs, and sheep: Shortening, candies, chewing gum

  • Pork: lard

• Intestines, small: Sausage casings

• Intestines, large (pork): Chitterlings

• Intestines, large: Sausage casings

• Esophagus (weasand): Sausage ingredient

• Pork skins: Fried pork skins, gelatin for confectioneries, ice cream, and jellied food products

• Calf skin trimmings: Gelatin for confectioneries, ice cream, and jellied food products

Examples of inedible meat by-products pt 1

• Hide (cattle and calves)

  • Leather: Numerous leather goods

  • Glue: Paper boxes, sandpaper, plywood sizing

  • Hair Felts, plaster binder, upholstery

• Pork skins: Tanned skin Leather goods

• Pelts

  • Wool: Leather goods

  • Skin: Textiles

  • Lanolin : Ointments

• Fats from cattle, calves, lambs, and sheep

  • Inedible tallow: Industrial oils, lubricants, soap, glycerin

• Fats from cattle, calves, lambs, sheep, and hogs

  • Tankage, cracklings, stick: Livestock and poultry feeds

Examples of edible meat by-products pt 2

• Fats from hogs

  • Grease: Industrial oils

• Bones

  • Dry bone: Glue, hardening steel, refining sugar (bone charcoal)

  • Bone meal: Animal feed and fertilizer

  • Blood albumen: Leather preparations, textile sizing

• Cattle feet

  • Neatsfoot stock: Fine lubricants

  • Neatsfoot oil: Leather preparations

• Glands

  • Pharmaceuticals: Medicines

  • Enzyme preparations: Industrial uses

• Lungs: Pet foods

Hides, skins, and pelts

• Unborn calf: Slunk skin

  • Never exposed to outside

• Calf

  • Light skin calf

  • Heavy skin calf

  • Kip skin

  • Overweight kip skin

• Cow

  • Light cow hide

  • Heavy cow hide

Hides, skins, and pelts - part 2

• Steer

  • Extra light steer hide

  • Light steer hide

  • Heavy steer hide

• Bull: Bull hide

• Stag: Accepted as steer or bull depending on its characteristics

Effect of brands

• Leather used for furniture, car seats, footballs, etc

• Native: Unbranded

  • Most valuable

• Butt brand

  • Branded on rump area -$3 per hide

• Colorado brand

  • Branded on side

Pelts

• Wool pelts (most valuable)

• Fall clips

• Shearlings 1

• Shearlings 2

• Shearlings 3

• Shearlings 4 (least valuable)

Tallows and Greases

• Titer – Congealing or solidification point of the fatty acids in the fat.

• Tallow – Fat having a titer above 40°C.

• Grease – Fat having a titer below 40°C.

• Dry rendering process – Fatty tissues are placed in horizontal, steam-jacketed cylinder equipped with sets of internal rotating blades. Fat cells are ruptured, and the melted fat is released from the supporting tissues. When sufficient moisture has cooked out, the mixture is filtered or strained to remove the cracklings from the rendered tallow or grease.

Animal feeds and fertilizers

• Dried blood (blood meal) – Made from coagulating fresh blood with steam, draining off the liquid, and drying the coagulum.

• Meat meal – Made from the proteinaceous materials from the inedible rendering process.

• Steamed bone meal – Made by cooking bones with steam, under a high pressure, in order to remove any fat and meat that may be left on them.

Gelatin and glue

• Gelatin – Made from skins or hides, connective tissues, cartilage, and bones of cattle and calves. Cooking in water converts the collagen in these materials to gelatin.

• Glue – Made from the same items as gelatin, but is extracted from these materials by successive heatings in water under specific temperature conditions.

Pharmaceuticals - Glands

• Adrenal – Epinephrine is extracted from the adrenal medulla and adrenocortical extract from the adrenal cortex.

• Ovaries – Used as a source of estrogens and progesterone.

• Pancreas – Yields insulin and trypsin.

• Parathyroid – Parathyroid hormone extract is used to prevent large-scale muscular rigidity.

• Pituitary – Source of ACTH (adrenocorticotropic hormone).

• Testes – Source of hyaluronidase.

• Thyroid – Source of thyroxine and calcitonin.

Pharmaceuticals- Tissues and organs

• Blood – Source of albumin and amino acids.

• Bone – Source of calcium and phosphorous.

• Intestines – Surgical sutures and condoms.

• Liver – Liver extracts and bile extract, which can be used to make cortisone.

• Lungs – Heparin.

• Spinal cord – Source of cholesterol, which is used to manufacture Vitamin D.

• Stomach – Rennet, from calves, mucin, from pigs, and pepsin, from pigs.

Pharmaceuticals - other by products

• Fetal calf blood – Used for cancer and AIDS research.

• Aorta valves – For replacement of defective human heart valves.

• Fetal pigs – Used for biology teaching.

• Gall stones – Used as aphrodisiacs in the Far East (chunks of cholesterol)

Meat

• Edible portions of domestic mammals used for food.

  • Poultry not considered meat

Class Names

• Bovine

  • < 3 months: veal

  • 3 to 9 months: calf

  • 1 to 2 years: beef

  • Greater than 2 years

• Ovine

  • < 3 months: hothouse lamb

  • 3 to 9 months: lamb

  • 1 to 2 years: yearling lamb

  • Greater than 2 years: Mutton

• Porcine

  • < 3 months: slaughter pig

  • 3 to 9 months: butcher hog

  • 1 to 2 years: packer sow, stag or boar

  • Greater than 2 years

• Caprine

  • < 3 months: cabrito

  • 3 to 9 months: kid

  • 1 to 2 years: yearling

  • Greater than 2 years: Adult

• Equine: all stages horse meat

Class names pt 2

• Hothouse lamb used for Easter and Passover

• Packer sow → Jimmy dean

• Boar → boar odor

• Stag → cats ration after getting secondary sex characteristics

Kinds of meat (made up of proteins, water, fat) - carcass

• Carcass – eviscerated body of domestic mammals.

• Major – bone, connective tissue, muscle, fat

• Minor – skin, arteries, nerves, veins

Kinds of meat (made up of proteins, water, fat) - variety meat

• Variety meat – edible organs and glands

• Kidney, liver, heart, tongue, sweetbread, stomach, tripe, etc.

Kinds of meat - reclaimed meat

• Reclaimed meat – products obtained from bone, fat or blood

  • Products that weren’t used, now are

• Mechanically separated beef and pork – from bone

• Lean finely textured beef – from fat

• Plasma protein isolate – from blood

• Pre BSE, used backbone

Kinds of meat - processed meats and carcass meat

• Processed meats

  • Frankfurters – made from carcass meat with options of variety meats and/or reclaimed meat plus cure ingredients

  • Ham and bacon – made from carcass meat

• Carcass meat – composed of bone, connective tissue, muscle, and fat.

Function in living animal - bone and connective tissue

• Bone

  • Protects organs

  • Levers for locomotion

  • Support and rigidity

• Connective tissue

  • Part of skeleton

  • Connects muscle to bones

  • Harness, collects activity of muscle fibers

Function in living animal - Muscle and Fat

• Muscle

  • Produces energetic

  • Converts energy to work

• Fat

  • Storage of reserve energy

  • Insulation

  • Protects vital organs

Muscle structure - muscle

• Muscle: Contractile organ composed of connective tissue, muscle fibers, and intramuscular fat.

• Epimysium: surrounds entire muscle

• Perimysium: surrounds muscle bundle

• Endomysium: surrounds muscle fiber

Muscle structure - connective tissue, intramuscular fat, and muscle fiber

• The Connective tissue

  • Fibrils of stromal proteins: Collagen, Elastin (ligamentum nuchae) and Reticulin

    • Protein most important

  • Dispersed in a watery matrix called ground substance (glycoproteins)

• Intramuscular fat

  • Deposits of fat in perimysium and endomysium

• Muscle fiber

  • Muscle cell, the smallest completely functional unit in the muscle.

  • 10 to 100 µm in diameter, 10 to 40 mm in length, striated appearance.

Muscle fiber, Myofibril, sarcomere components

• Myofibril: (2,500 per fiber), 8,000 sarcomeres per Myofibril

• Sarcomere: basic contractile unit, longer it is, more tender

• Toughest meat after 1 day after postmortem

Muscle fiber

Is Multinucleated

A band and I band

• A band: region of the muscle fibers, myofibrils and sarcomeres that contains both thick and thin myofilaments.

• I band: region of the muscle fibers, myofilaments and sarcomeres that contain thin myofilaments only (Z-lines are in the middle of I-Bands)

Thick and thin filaments

• Thick myofilaments – primarily composed of myosin.

• Thin myofilaments – primarily composed of actin, tropomyosin, and troponin.

M and Z line & H zone

• M-line – structural protein that holds the thick myofilaments in register.

• Z-line – structural protein that holds the thin myofilaments in register and serves to separate sarcomeres.

• H-zone – region of the A-Band that contains only thick myofilaments.

Tenderness measurements in meat science research

• Trained and/or consumer sensory panels (9 = extremely tender; 1 = extremely tough)

• Warner-Bratzler shear (WBS) force (1/2-inch core removed from cooked steak, parallel to the muscle fibers, and mechanically sheared: lower values more tender than higher values)

Relative rank in tenderness - tender, intermediate

• Tender

  • Psoas major

  • Infraspinatus ( 2nd most tender )

  • Gluteus medius

  • Longissimus dorsi

  • Triceps brachii

• Intermediate

  • Biceps femoris (sirloin, largest muscle in carcass)

  • Rectus femoris

  • Adductor

  • Semitendinosus

  • Semimembranosus

  • Biceps femoris (round)

PIGLT BRASS DLTS (with Biceps femoris from sirloin)

PIGLT RASSB DLTS (with Biceps femoris from round)

Relative rank in tenderness - Tough

• Tough

  • Deep pectoral

  • Latissimus dorsi

  • Trapezius

  • Superficial pectoral

Tenderness rankings of selected bovine muscles

Know which muscle is more tender than another

Top Ten “Tender” and “Tough” cuts in WBS from the National Beef Tenderness Survey 1990 - tender cuts

Tender cuts in lbs

• Tenderloin steak 5.7

• Top blade steak 6.7

• Top loin steak 7.2

• Rib roast 7.3

• Rib steak 7.4

• Ribeye steak 7.5

• Chuck roll roast 7.6

• Clod roast 7.9

• Round tip roast 7.9

• Top sirloin steak 8.0

Top Ten “Tender” and “Tough” cuts in WBS from the National Beef Tenderness Survey 1990 - tough cuts

Tough in lbs

• Top round steak 11.7

• Eye of round steak 10.3

• Bottom round steak 9.7

• Rump roast 9.5

• Eye of round roast 9.2

• Chuck roll steak 9.2

• Chuck tender steak 9.0

• Top round roast 9.0

• Bottom round roast 8.9

• Round tip steak 8.9

Key findings from National Beef Tenderness Survey 1990

• Tenderloin steak and top blade steaks ranked first and second

• Top round steak ranked last

• Roasts were more tender than steak counterparts

Differences among muscles

• Actomyosin effect

• Background effect

• Bulk density or lubrication effect

Actomyosin effect

• Sarcomere length (longer, more tender)

• Muscle fiber diameter

• Sarcomere/fragment

Background effect

• Concentration of stromal proteins (elastin, reticulin, collagen)

• Size of elastin fibrils

• Solubility of collagen (older animal has less)

Bulk density/lubrication effect

• Amount of marbling

• Distribution of marbling

Comparisons between “Tender” and “Tough” steaks - Tender

Tender steaks

• Sarcomere length: longer

• Muscle fiber diameter: half diameter compared to tough steak

• Sarcomere/fragment: more fragmented

• Amount of stromal protein: less

• Size of elastin fibrils: less

• Collagen solubility: more

• Amount of marbling: more/moderate

• Distribution of marbling is extensive

Comparisons between “Tender” and “Tough” steaks - tough

• Sarcomere length: shorter

• Muscle fiber diameter: twice diameter compared to tender steak

• Sarcomere/fragment: less fragmented

• Amount of stromal protein: more

• Size of elastin fibrils: more

• Collagen solubility: less

• Amount of marbling: less

• Distribution of marbling is collected

Additional factors affecting tenderness

• Breed type – Bos indicus (Brahman, Sahiwal, etc.) breeds tend to be tougher than Bos taurus breeds (Angus, Hereford, etc.). Bos indicus has greater amounts of calpastatin, a protein that interferes with postmortem degradation of muscle.

• Locomotive versus support muscles – less connective tissue in support muscles.

  • Locomotive is tough, support tender

Additional factors affecting tenderness Pt 2

• Quality grade effects – Prime has more marbling than Choice and Choice has more than Select.

  • Prime > choice > select

• Degree of doneness – as meat is cooked to more advanced degrees of doneness, the tougher it will get. Marbling helps to “insure” acceptable tenderness at higher levels of doneness.

How to make meat more tender

• Cause the sarcomeres to be longer.

• Disrupt the integrity of the myofibrils.

• Disrupt the integrity of the connective tissue

Cold shortening

• Discovered near 1963, Process whereby sarcomeres shorten due to cold-induced nervous response. Results in tougher meat.

  • Not good , happens most in heavier carcasses

• At 16 degrees C, least amount of cold shortening

To prevent cold shortening

• Speed-up drop in pH in muscle (anaerobic glycolysis: glycogen → lactic acid; muscle pH 7.0 →5.6)

  • Gets rid of enzymes that do contractions, tougher meat

• And/or Slowdown drop in muscle temperature.

Cause sarcomeres to be longer - prevent cold shortening

• Subcutaneous fat thickness – 0.10 inch in lamb; 0.25 inch in beef. Slows down temperature drop in muscle. (Pork doesn’t cold-shorten because of “white” muscle fibers.)

• High temperature, pre-rigor chilling – 16°C for 16 hours immediately after slaughter.

  • Rigor mortis sets in, no cold shortening

• Electrical stimulation – 550 volts, 2 to 6 amps, 15 times in one minute. Very rapid drop in muscle pH and quicker onset of rigor mortis.

Cause sarcomeres to be longer - stretch the sarcomeres

• Texas A&M Tenderstretch — suspension by the obturator foramen (aitch bone). Hindleg acts as a cantilever.

  • If not hung by Achilles, tender loin will end up more tough

• Stouffer's Stretching Devices — TAMU Tenderstretch plus clamps and stretching rods.

• TenderCut™ – bones (12th to 13th rib) and connective tissues are cut around muscles to allow stretching.

Disrupt the myofibrils - Increased activity of endogenous enzymes, calpains and calpastatin

• Calpains – stored in the cytosol near Z-lines and require calcium to be activated

• Calpastatin – regulates calpains; the higher the calpastatin levels and activity, the less breakdown of myofibrils.

  • Inhibitor for calpains

  • More in Bos Indicus

Increased activity of endogenous enzymes - cooler aging and temperature

• Cooler aging – storage for 1 to 6 weeks at 0-3°C.

• High temperature, post-rigor chilling – Storage at 20°C for 24 hours. Same effect as 2°C for 14 days.

• High temperature, pre-rigor chilling – 16°C for 16 hours.

Increased activity of endogenous enzymes - electrical stimulation and calcium chloride injection

• Electrical stimulation – rapid pH decline ruptures lysosome and releases cathepsins.

• Calcium chloride infusion/injection – pre-rigor infusion or post-rigor injection of a solution of calcium chloride into muscle. Causes increased activity of calpains.

Disrupt the myofibrils - Addition of exogenous enzymes

• Tropical plant enzymes – Heat activated: Swift's Pro-Ten® (inject into live animal) or Adolph's Meat Tenderizer® (sprinkle on meat).

• Papain — papaya;

• Bromelin — pineapple

• Ficin — fig;

• Actinidin — kiwi fruit

• They degrade enzymes, heat deactivated to stop enzyme degradation

Disrupt the myofibrils - Severance of myofibrils

• Electrical stimulation: violent contractions cause myofibril tearing.

• Blade or needle tenderizer: machines with multiple blades and/or needles that penetrate meat as it passes through on a conveyor. First machine was Jaccard (most people call the process “Jaccarding”).

• Mechanical severance: scoring, dicing, cubing, grinding or chopping.

• Hydrodyne™: placing meat in a sealed water-filled chamber and setting off an explosion. Destroys most of the Z-lines to greatly improve tenderness.

Disrupt connective tissue - Use of exogenous enzymes

• Marination with salt and vinegar – water solution with 2% NaCl plus acetic acid.

• Rhozyme use of fungal enzyme: Aspergillus oryzae.

• Tropical plant enzymes (ficin works best)

Disrupt connective tissue - Severance of stromal proteins

• Blade or needle tenderization

• Mechanical severance

Disrupt connective tissue - Conversion of collagen to gelatin

Moist-heat cookery – cook for a long time with steam generation: braise, stew, simmer

Key terms used to describe color

Hue, chroma, and value

• Hue – words we normally think of as describing , purple, blue, etc.

• Chroma – strength or dominance of the hue

• Value – overall intensity to how light or dark a color is.

L*, a*, b* color space (pronounced “L-star, a-star, b-star) for instrumental measurements

• L* – black to white

  • L= 100 white, L=0 black, PSE closer to L=60 and DFD lower L

• a* – red to green

  • -a to +a

• b* – yellow to blue

  • +b to -b

Structure of myoglobin

Pigment hold oxygen in animal, small protein

Hemoglobin versus myoglobin

• Hemoglobin – transports O2 from lungs to cells

  • Not a lot left after bleeding

• Myoglobin – stores O2 in cells

Meat color is impacted by … - age within species

• myoglobin loses its affinity to bind oxygen as age increases

• Age class

  • Veal (least myoglobin concentration)

  • Calf

  • Young beef

  • Old beef (most myoglobin concentration)

Meat color is impacted by … - Species differences

• age related as well as differences between “red” versus “white” muscle fibers

• Species and meat color

  • Pork, pink, least myoglobin concentration

  • Lamb, light red

  • Beef, cherry red, most myoglobin concentration

Meat color is impacted by … - Type of muscle

• the more a muscle is used, the more myoglobin it needs

• Type of muscle and muscle name

  • Locomotive: M. extensor carpi radialis, most myoglobin concentration

  • Support: M. longissimus thoracis et lumborum, least myoglobin concentration

Chemical state of myoglobin - covalent bond Fe

• Fe++ Ferrous (covalent bond)

  • :H2O, purple, Deoxymyoglobin

  • :O2, Red, Oxymyoglobin

  • :NO, Cured pink, Nitric oxide myoglobin

  • :CO, Red ,Carboxymyoglobin

    • Only was used in small trace amounts, no long used as it was seen as deceptive to consumers

Chemical state of myoglobin - ionic bond Fe

• Fe+++ Ferric (ionic)

• –CN, Red, Cyanmetmyoglobin

• –OH, Brown, Metmyoglobin

• –SH, Green, Sulfmyoglobin

• –H2O2, Green, Choleglobin

Transformation of myoglobin

Metmyoglobin Reducing Activity (MRA)

• The system in muscle that converts metmyoglobin back into deoxymyoglobin (without oxygen) and oxymyoglobin (with oxygen) through a series of reactions until the reductants are depleted.

  • High MRA = M. longissimus lumborum

  • Low MRA = M. psoas majo

Oxygen Consumption Rate (OCR)

• The respiration rate of muscles over time during display, which competes with the myoglobin for enough oxygen to keep the muscle in the oxymyoglobin state.

  • High OCR = M. psoas major

  • Low OCR = M. gluteus medius

Color stability varies across muscles

Two meat color problems with cooked ground beef - Premature Browning

• Usually caused by highly oxidized meat or meat that is exposed to high-oxygen atmospheres

• Meat will turn brown around 130°F internal temperature.

• Reason why color is not a good indicator of cooked meat

Two meat color problems with cooked ground beef - Persistent Pinkness

• Usually caused by high pH meat.

• Product will stay pink (uncooked color) even with degrees of doneness that should ensure appropriate cooked endpoints are followed

Vitamin E feeding of cattle

• Vitamin E can be fed to livestock to increase the alpha-tocopherol concentration in muscle.

• Alpha-tocopherol is an antioxidant and retards the conversion of deoxymyoglobin (purple) or oxymyoglobin (red) to metmyoglobin (brown).

Activity of bacteria

• Oxymyoglobin + oxidation + bacteria = metmyoglobin (–OH)

• Metmyoglobin + bacteria = choleglobin (–H2O2)

• Metmyoglobin + bacteria = sulfmyoglobin (–SH)

Curing

• Deoxymyoglobin, oxymyoglobin, metmyoglobin + NO = nitric oxide myoglobin

• Nitric oxide myoglobin + heat = nitrosyl hemochromogen

Wrapping film

• Vacuum packages (polyvinylidene chloride–polyvinyl chloride); barrier to O2

• Retail film (polyvinyl chloride); permeable to O2

• Higher storage life, prevents bacteria