Exam 3 Property of Fresh Meats

Question 1

major factors that affect meat freshness

Answer 1

• visual appearance
• flavor
• juiciness
• tenderness

Question 2

things that affect fresh meat pigments

Answer 2

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

Question 3

things with higher myoglobin content

Answer 3

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

Question 4

factors affecting meat color

Answer 4

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

Question 5

chemical state of heme iron in myoglobin is influenced by

Answer 5

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

Question 6

heme

Answer 6

• 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

Question 7

DMB

Answer 7

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

Question 8

OMB

Answer 8

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

Question 9

MMB

Answer 9

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

Question 10

CO-MB

Answer 10

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

Question 11

mitrosomyoglobin

Answer 11

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

Question 12

effects of adding vitamin e

Answer 12

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

Question 13

ferrous (Fe++) H2O

Answer 13

purple -> deoxymyoglobin

Question 14

ferrous (Fe++) O2

Answer 14

red -> oxymyoghobin

Question 15

ferrous (Fe++) NO

Answer 15

unstable pink -> nitric oxide myoglobin

Question 16

ferrous (Fe++) CO

Answer 16

red -> carboxymyoglobin

Question 17

ferric (Fe+++) H2O (globin)

Answer 17

brown -> metmyoglobin

Question 18

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

Answer 18

brown/gray -> denatured metmyglobin

Question 19

ferric (Fe+++) SH

Answer 19

green -> sulfmyoglobin

Question 20

HH2O2 (hydrogen peroxide)

Answer 20

green -> choleglobin

Question 21

sodium nitrate

Answer 21

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

Question 22

nitrosamines

Answer 22

• proteins (amines) combined with nitrites

- cancer-causing

Question 23

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

Answer 23

ascorbic acid / antioxidant

Question 24

flavor component of fat

Answer 24

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

Question 25

flavor component of lean meat

Answer 25

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

Question 26

fatty acid oxidation

Answer 26

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

Question 27

relative rate of oxidation

Answer 27

1:100:1200:2500

Question 28

oxidative deterioration of fats

Answer 28

rancid / off odor and off flavor

Question 29

what factors affect juiciness

Answer 29

- water holding capacity - lipids (oils) in meat - cooking

Question 30

tissue factors affect tenderness

Answer 30

- rigor toughening - post mortem proteolysis - connective tissue - intramuscular fat

Question 31

factors influencing meat tenderness

Answer 31

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

Question 32

proteolysis

Answer 32

- protein degration or breakdown | - causes meat tenderization

Question 33

calpains

Answer 33

- calcium activated proteases (breakdown proteins) - high calpastatin = tougher meat - inhibited by calpastatin

Question 34

shorter sarcomere

Answer 34

- tougher meat - actin and myosin squished together - length .8

Question 35

what does calpain act or not act on / breakdown

Answer 35

- 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)

Question 36

regulators of tenderness

Answer 36

- collagen content and solubility - sarcomere length - post mortem proteolysis

Question 37

marbling effects on tenderness

Answer 37

- very little! | - marbling effects juiciness and flavor not really tenderness

Question 38

how to cook high collagen products

Answer 38

slow, moist heat (crock pot)

Question 39

how to cook low collagen products

Answer 39

dry cookery (grill)