Exam 3 Property of Fresh Meats Flashcards Preview

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Flashcards in Exam 3 Property of Fresh Meats Deck (39)
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1

major factors that affect meat freshness

-visual appearance
-flavor
-juiciness
-tenderness

2

things that affect fresh meat pigments

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

3

things with higher myoglobin content

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

4

factors affecting meat color

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

5

chemical state of heme iron in myoglobin is influenced by

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

6

heme

-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

7

DMB

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

8

OMB

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

9

MMB

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

10

CO-MB

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

11

mitrosomyoglobin

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

12

effects of adding vitamin e

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

13

ferrous (Fe++) H2O

purple -> deoxymyoglobin

14

ferrous (Fe++) O2

red -> oxymyoghobin

15

ferrous (Fe++) NO

unstable pink -> nitric oxide myoglobin

16

ferrous (Fe++) CO

red -> carboxymyoglobin

17

ferric (Fe+++) H2O (globin)

brown -> metmyoglobin

18

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

brown/gray -> denatured metmyglobin

19

ferric (Fe+++) SH

green -> sulfmyoglobin

20

HH2O2 (hydrogen peroxide)

green -> choleglobin

21

sodium nitrate

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

22

nitrosamines

-proteins (amines) combined with nitrites
-cancer-causing

23

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

ascorbic acid / antioxidant

24

flavor component of fat

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

25

flavor component of lean meat

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

26

fatty acid oxidation

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

27

relative rate of oxidation

1:100:1200:2500

28

oxidative deterioration of fats

rancid / off odor and off flavor

29

what factors affect juiciness

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

30

tissue factors affect tenderness

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