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ASCI 211 > Exam 3 Property of Fresh Meats > Flashcards

Exam 3 Property of Fresh Meats Flashcards

1
Q

major factors that affect meat freshness

A
  • visual appearance
  • flavor
  • juiciness
  • tenderness
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2
Q

things that affect fresh meat pigments

A
  • myoglobin content (80-95%)
  • hemoglobin (from residua; blood)
  • cytochromes, catalase (oxidative enzymes)
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3
Q

things with higher myoglobin content

A
  • male more than female
  • older more than younger
  • red muscle more than white
  • physical activity more than
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4
Q

factors affecting meat color

A
  • muscle pH
  • rate of pH decline
  • uneven chilling
  • chemical state of heme iron in myoglobin
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5
Q

chemical state of heme iron in myoglobin is influenced by

A
  • type of packaging (time exposed to air)
  • microbial contamination
  • age of meat
  • cooking
  • curing
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6
Q

heme

A
  • located in center of protoporphyrin (organic component) bound with 4 pyrrole rings
  • 5th binding site is occupied by a histidine residue
  • 6th binding site is available to bind oxygen
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7
Q

DMB

A
  • deoxymyoglobin
  • Fe++ (ferrous)
  • no O2 present
  • purple
  • loses oxygen
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8
Q

OMB

A
  • oxymyglobin
  • Fe++ (ferrous)
  • atmospheric O2
  • red
  • gains oxygen/ exposed to air so loses binding ability to electrons
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9
Q

MMB

A
  • metmyglobin
  • Fe+++ (ferric)
  • low O2 present
  • brown
  • denatured bc loses electrons
  • irreversible after adding heat
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10
Q

CO-MB

A
  • carboxymyoglobin
  • Fe++ (ferrous)
  • CO present
  • red
  • strong binding component to heme
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11
Q

mitrosomyoglobin

A
  • meat after nitric acid is added
  • permanently fixed pink color
  • add heat to get nitrosohemocrome
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12
Q

effects of adding vitamin e

A
  • antioxidant so the myoglobin content is protected from denaturation
  • myoglobin extends shelf land brighter color
  • less retail cuts discounted with vitamin e
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13
Q

ferrous (Fe++) H2O

A

purple -> deoxymyoglobin

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14
Q

ferrous (Fe++) O2

A

red -> oxymyoghobin

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15
Q

ferrous (Fe++) NO

A

unstable pink -> nitric oxide myoglobin

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16
Q

ferrous (Fe++) CO

A

red -> carboxymyoglobin

17
Q

ferric (Fe+++) H2O (globin)

A

brown -> metmyoglobin

18
Q

ferric (Fe+++) H20 (denatured globin)

A

brown/gray -> denatured metmyglobin

19
Q

ferric (Fe+++) SH

A

green -> sulfmyoglobin

20
Q

HH2O2 (hydrogen peroxide)

A

green -> choleglobin

21
Q

sodium nitrate

A

smaller % of sodium nitrate coverts to sodium nitrite after eaten (can form nitrosamines)

22
Q

nitrosamines

A
  • proteins (amines) combined with nitrites

- cancer-causing

23
Q

veggies contain ______ which is an ______ that helps prevent nitrosamine formation

A

ascorbic acid / antioxidant

24
Q

flavor component of fat

A
  • protein/ ATP breakdown products (IMP, hypoxanthine)
  • affected by feed, animal age, gender
  • lipid oxidation/ rancidity, microbes
25
Q

flavor component of lean meat

A
  • fat component has to be under 1% to be considered fat free
  • meaty flavor
  • browning reaction
  • amino groups + reducing sugars = melanoidins
26
Q

fatty acid oxidation

A

18: 1 (36)
18: 2 (4)
18: 3 (trace)

27
Q

relative rate of oxidation

A

1:100:1200:2500

28
Q

oxidative deterioration of fats

A

rancid / off odor and off flavor

29
Q

what factors affect juiciness

A
  • water holding capacity
  • lipids (oils) in meat
  • cooking
30
Q

tissue factors affect tenderness

A
  • rigor toughening
  • post mortem proteolysis
  • connective tissue
  • intramuscular fat
31
Q

factors influencing meat tenderness

A
  • vitamin D feeding
  • stress
  • muscle location
  • fiber size
  • carcass (hanging method, aging 7-21 days)
  • mechanical (grinding, macerating)
  • marinade/ injection (cooking)
32
Q

proteolysis

A
  • protein degration or breakdown

- causes meat tenderization

33
Q

calpains

A
  • calcium activated proteases (breakdown proteins)
  • high calpastatin = tougher meat
  • inhibited by calpastatin
34
Q

shorter sarcomere

A
  • tougher meat
  • actin and myosin squished together
  • length .8
35
Q

what does calpain act or not act on / breakdown

A
  • not act on contractile proteins (actin and myosin)
  • not act on stromal proteins (collagen, keratin, elastin)
  • act on myofibrilliar, non-contractile proteins (desmin, titan, troponin)
36
Q

regulators of tenderness

A
  • collagen content and solubility
  • sarcomere length
  • post mortem proteolysis
37
Q

marbling effects on tenderness

A
  • very little!

- marbling effects juiciness and flavor not really tenderness

38
Q

how to cook high collagen products

A

slow, moist heat (crock pot)

39
Q

how to cook low collagen products

A

dry cookery (grill)

ASCI 211 (11 decks)

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