Chapter 10 Meat Color

What key terms are used to describe color?

• Hue, chroma, and value

• :L*,a*,b* color space for instrumental measurements

Define hue

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

Define Chroma

strength or dominance of the hue

Define Value

overall intensity to how light or dark a color is.

What colors do L* measure?

black to white

What colors do a* measure?

red to green

What colors do b* measure?

yellow to blue

fill in the blanks for the structure of myoglobin

What’s the difference between Hemoglobin and Myoglobin?

Hemoglobin – transports O2 from lungs to cells

• in blood

Myoglobin – stores O2 in cells

What factors impact meat color?

• Quantity of myoglobin

  • Age within species

  • species differences

  • Type of muscle

• Chemical State of myoglobin

Why does Age within a species affect the quantity of myglobin?

myoglobin loses its affinity to bind oxygen as age increases

(T/F) a calf would less myoglobin than an old beef

true, because their myoglobin works efficiently so they require less for the same function

Why does species difference impact the quantity of myoglobin?

differences between “red” versus “white” muscle fibers

What is the color of pork and myoglobin concentration?

Pink, 2 mg/g

What is the color of lamb and myoglobin concentration?

Light red, 6 mg/g

What is the color of beef and myoglobin concentration?

Cherry red mg/g

(T/F) the redder the meat, the less myoglobin present

False, myoglobin concentration increases with redder colors

Why does the type of muscle impact the quantity of myoglobin?

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

(T/F) the muscle M. extensor carpi radialis (locomotive) has more myoglobin than the muscle M. longissimus thoracis et lumborum (support)

true, the more locomotive the muscle, the more myoglobin it contains

What covalent compound keeps meat red and has a 8x greater affinity

Carboxymyoglobin (CO)

What color is a meat with compound Deoxymyoglobin?

Purple

What color is a meat with compound metmyoglobin?

Brown

What color is a meat with compound oxymyoglobin?

Bright red

fill in the blanks

What does MRA stand for and what is it?

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.

What kinds of muscles have high MRA?

“High” color stability muscles

What kinds of muscles have low MRA? (hint- eats oxygen)

“Very low” color stability muscles

What does OCR stand for and what is it?

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.

What kinds of muscles have high OCR?

“Very low” color stability muscles

What kinds of muscles have low OCR?

“intermediate-very low” color stability

What muscles have “high” color stability?

• M. longissimus lumborum

• M. longissimus thoracis

• M. semitendinosus

• M. tensor fasciae latae

What muscles have “low” color stability?

• M. supraspinatus

• M. infraspinatus

• M. psoas major

What two meat color problems with cooked ground beef?

• Premature Browning

• Persistent Pinkness

Describe 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.

Describe 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.

what are the benefits of 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).

What if the formula for metmyoglobin? (-OH)

Oxymyoglobin + oxidation + bacteria = metmyoglobin

What if the formula for choleglobin (–H2O2)?

Metmyoglobin + bacteria = choleglobin

What if the formula for metmyoglobin? (-OH)

Metmyoglobin + bacteria = sulfmyoglobin

What is the curing formula for nitric oxide myoglobin?

Deoxymyoglobin, oxymyoglobin, metmyoglobin + NO = nitric oxide myoglobin

What is the curing formula for nitrosyl hemochromogen?

What are the two types of wrapping film?

• Vacuum packages (polyvinylidene chloride–polyvinyl chloride)

• Retail film (polyvinyl chloride)

What is the difference between the vacuum packages and retail film?

vacuum packages - barrier to O2

retail film - permeable to O2