Meat Color (Exam 4) Flashcards
If there is more myoglobin, what is the color of meat like?
Darker
What is myoglobin?
Water soluble globular protein
What are the 8 α-helices in myoglobin?
A, B, C, D, E, F, G, H
What is within the 8 α-helices in myoglobin?
Heme rings
What is the structure of heme rings?
4 pyrrole ring structure
Iron atom at the center
How many iron binging site does myoglobin have? Where are they?
6
4 bonded to heme ring
1 bonded to proximal HIS-93
1 bonded to ligands
Look at chart on slide 11
Look at chart on slide 11
What are the 2 oxidation states of iron?
Ferrous
Ferric
What happens when there is ligated iron and meat color: Mb/DMb (water added)?
Ferrous for heme Fe
Why does stuff happen when there is ligated iron and meat color: Mb/DMb (water added)?
Very low O2
Only water to bond
Where do reactions happen when there is ligated iron and meat color: Mb/DMb (water added)?
Uncut or vacuum-packaged meat
What color is meat when there is ligated iron and meat color: Mb/DMb (water added)?
Purplish-red or purplish-pink
What happens when there is ligated iron and meat color: OMb (oxygen added)?
Ferrous for heme Fe
Why does stuff happen when there is ligated iron and meat color: OMb (oxygen added)?
Exposed to oxygen or air
At least 40 torr of O2
1 binding site occupied by diatomic oxygen
Distal histidine stabilizes Fe-O2 bond
Where do reactions happen when there is ligated iron and meat color: OMb (O2 added)?
Blooming meat cute
Over-wrapped, Hi-Ox MAP
What color is meat when there is ligated iron and meat color: OMb (O2 added)?
Purplish-red or purplish-pink
What happens when there is ligated iron and meat color: MMb (OH added)?
Ferric for heme Fe
Why does stuff happen when there is ligated iron and meat color: MMb (OH added)?
Low O2
Low MRA
Low O2 transmission rates
Where do reactions happen when there is ligated iron and meat color: MMb (OH added)?
Oxidized meat cuts prolonged exposure to O2
Deep layer of Omb without enough O2
What color is meat when there is ligated iron and meat color: MMb (OH added)?
Brown
What is activated when SH is added?
Sulfmyoglobin
What is the order of meat color changes?
Red to pink to tan to brown
What are remedies to preservation?
Feed supplement (vitamin E)
Preservaitves sprayed
Active packaging
