meat science exam 4

Question 1

what country eats the most meat?

Answer 1

US, Brazil, Canada, UK, China

Question 2

what is the read meat vs poultry consumption trend?

Answer 2

reduced red meat intake but increased poultry consumption

Question 3

long term beef consumption trend

Answer 3

consumption for all types of beef steadily declined over the long term

Question 4

American’s red meat trend

Answer 4

most americans eat <3 1/2 oz red & processed meat/day, 71% of US population eats red meat = above recommended for “total protein foods” & “total meat”, less recommended for “red meat”

Question 5

males vs female meat poultry egg consumption

Answer 5

male above average vs females marginally below recommended

Question 6

vegtable consumption

Answer 6

overall very below recommended

Question 7

trends for america eating less red meat (most - least)

Answer 7

health reasons, other meats seem healthier, limiting cholesterol/fat, too expensive, farming concern, eating more plant-based,

Question 8

obesity rate trends

Answer 8

obesity rates have increased during the same time

Question 9

caloric consumption trends

Answer 9

1970 to 2008 a 30% caloric intake increase (2,057 - 2,674) 70% of calories from plant based foods, added fats and oils 403 to 616, flour cereal products 432 to 625 kcal, Americans consume 2x refined grains recommended, added sugars contribute 16% total calories

Question 10

todays meat lean & nutrien

Answer 10

todays meat supply is leaner &nutrien dense, beef external fat has decreased 80% in past 20 yrs

Question 11

lean red meat accessibility to public

Answer 11

65% of beef cuts in the fresh meat case are lean, pork is similar (16% leaner than 20 yrs ago)
lean = <10g total fat, <4.5g saturated fat, <95mg cholesterol

Question 12

todays pork

Answer 12

pork tenderloin is just as lean as skinless chicken breast, 7 cuts of pork are classsifies as lean or extra lean including: rib chops, loin chops, and pork tenderloin, serves as an excellent sources of essential nutrients

Question 13

ground beef shifts

Answer 13

there are ongoing shifts to leaner ground beef

Question 14

red meat nutrients

Answer 14

red meat is nutrient dense, 48% protein, 41 %selenium, 37% B12, 33% zinc, while there is only 8% calories
beef consumption today contributes to only 5% of calories yet more than 5% of 8 essential nutrients (b12, zinc, protein, nicain, B6)

Question 15

unintended consequences of inadequate meat consumption (vit/min)

Answer 15

vitamin/mineral deficiencies especially iron, lean red meats are excellent source of heme iron (essential for red blood cell production, anemia prevention) heme iron from red meats is bioavailable

Question 16

unintended consequences of inadequate meeat consumption (sarcopenia)

Answer 16

sarcopenia: condition associated with loss of muscle mass and strength in older individuals (decreased stamina, increased risk of falling & bone fractures) often associated with decreased protein consumption

Question 17

benefits of fats found in meat

Answer 17

dietary fat source is essential for: nutrient absorption (fat soluble vitamins D E A K) maintenance of nervous system pathways & cell membrane integrity, lean red meats are an excellent source of many beneficial fatty acids

Question 18

fatty acid profile of beef

Answer 18

50% monounsaturated fatty acids, polyunsaturated fatty acids 4%, majority is unsaturated (better than saturated)

Question 19

fatty acid profile of pork

Answer 19

50% monounsaturated fatty acids, polyunsaturated fatty acids 11%

Question 20

salmon benefits

Answer 20

omega-3, 35 times and 47 times as much omega-3 as does grass or grain finished beef respectively

Question 21

red meat diet studies

Answer 21

20+ randomized control trials consistenty show healthy diets with 4-6oz lean red meat improves
cholesterol, blood pressure, weight management

Question 22

overall meat summary

Answer 22

Increase of diabetes heart disease obesity but increase in protein consumption and decrease in red meat, not correlated

Question 23

5 things that drive meat quality

Answer 23

tenderness, juiciness, flavor, color, odor

Question 24

3 driving attributes of palatability

Answer 24

flavor > tenderness > juiciness

Question 25

meat palatability

Answer 25

tenderness is essential for consumer acceptance, 90% of US steaks are considered “tender” or “very tender”, tenderness is influenced by contractile state, sarcomere length marbling etc (not just marbling = halo effect) only 10% variation in tenderness explained by marbling, 2% marbling needed for acceptable tenderness, once in acceptable range for being tender then flavor becomes more important for eating satisfaction

Question 26

met tenderness

Answer 26

tenderness is essential for consumer acceptance, tenderness is one of few variables that ADDS VALUE

Question 27

what influences tenderness

Answer 27

contractile state of the muscle (sarcomere length) enzymatic degradation of proteins, connective tissue, marbling

Question 28

marbling and halo effect

Answer 28

only 10% of variation in tenderness is explained by marbling, marbling helps to lubricate the mouth and reduce density, at least 2% marbling is need for “acceptable tenderness”

Question 29

flavor perception

Answer 29

flavor is based on perception not sensation = combination of taste and aroma

Question 30

what is taste vs odor perceived/detected by

Answer 30

taste is perceived by taste buds primarily on the tongue vs odor/aroma is detected by the olfactory system

Question 31

odor/aroma

Answer 31

greatest contributor to perceived flavor, low molecular weight volatile compounds bind to olfactory receptors and are responsible for perceived flavors

Question 32

what are basic taste in meat (food in general)

Answer 32

sweet, sour, bitter, salty, umami

Question 33

odor/aroma in meat

Answer 33

raw meat has little aroma and a blood-like taste, raw meat develop into flavor and odor causing compounds as a result of the chemical reactions that occur during cooking

Question 34

Maillard reaction

Answer 34

basic cooked meat flavor system which combines amines and sugars to produce a “meaty” flavored: bake things to get golden brown/toast

Question 35

amount and composition of IM fat affects the flavor profile of meat

Answer 35

IM lipids and associated volatiles produced during cooking are primary contributors flavor and aroma of meat
animal production practices that affect meat flavor do so primarily via effects on the amount and composition of IM fat

Question 36

grain-finishedbeef

Answer 36

grain-finishing for 100 or more days produces grain-fed beef flavor
most beneficial changes in lipid composition and beef flavor occur during the first 84 to 112 days on feed

Question 37

pre-harvest stress influences flavor

Answer 37

important to avoid stress with handling and transport prior to harvest
compared with normal beef dark cutting beef has a less desirable flavor with higher incidence of off-flavors (sour, bitter, soapy, bloody-like) PSE pork tends to have acidic taste

Question 38

forage finished beef

Answer 38

higher levels of omega-3 polyunsaturated fatty acids, trans fatty acids and stearic acid all of which are negatively correlated with flavor desirability
characterized as: grassy, gamey, livery, milky/oily, fishy

Question 39

grain-finished beef

Answer 39

higher levels of oleic & linoleic acid and other monounsaturated fatty acids all of which are positively correlated with flavor desirability
desired beef fat flavor often characterized as buttery

Question 40

factors affecting flavor

Answer 40

species, red meat species and poultry
breed, indicus vs taurus
sex, androstenone vs skatole
diet, grain vs grass
age, young lamb vs mutton
packaging, MAP vs over-wrap vs vacuum
fat, amount and type
muscle, location effect
aging, dry vs wet
enhancement, bring a solution containing salt
cooking method

Question 41

what processes deteriorate meat quality

Answer 41

bacterial, chemical, enzymatic, physical

Question 42

shelf life definition

Answer 42

maintenance of desirable properties (tenderness, juiciness, flavor, odor, COLOR)

Question 43

Importance of meat color

Answer 43

consumer base purchasing decisions off of meat quality becaase of the perceived quality (more important than any other factor)
color can be an indicator of freshness or wholesomeness if not bright cherry red than may be considered spoiled

Question 44

meat color discoloration acceptability

Answer 44

if there is a 20% meat discoloration then there is discrimination by consumers vs if there is a 40% discoloration then there is by rejection by consumers
15% of retail beef discounted due to discoloration which has an annual revenue loff of 3.7 billion

Question 45

how is meat color measured

Answer 45

CIE L, a, and b values
L = lightness 0 to 100
a = redness +60 to -60
b = yellowness +60 to -60

hue = trueness of red
chroma = intensity of degree of color saturation

Question 46

myoglobin

Answer 46

primary protein responsible for meat color, contains 8 aloha helices and a prosthetic group
water soluble and contains protein and non-protein portions

Question 47

heme ring

Answer 47

centrally located Fe that can form six bonds, 4th bonf with pyrrole nitrogen, 5th bond with proximal histidine
6th binding site can reversibly bind ligands (other compounds)
nature of group attaches to 6th binding site and chemical state of iron determines meat color

Question 48

chemical state of iron

Answer 48

color influenced by compounds that interact with Fe in the heme ring

Question 49

ability to bind with myoglobin depends on what

Answer 49

valance (charge) of Fe
Fe 3+ (oxidized myoglobin) ferric iron –enzymatic activity–> fe 2+ (reduced myoglobin) ferrous iron –low quantities of O2–> fe 3+ ferric

Question 50

the valence state of Fe depends on

Answer 50

availability of electrons, ETC, enzymes use residual O2 long after harvest

Question 51

chemical form of myoglobin

Answer 51

primary forms of myoglobin = deoxymyoglobin,, oxymyoglobin, metmyoglobin, carboxymyoglobin

Question 52

deoxymyoglobin

Answer 52

occurs when H2O or no ligand is available for binding to 6th site, hee iron is FERROUS 2+, purplish-pink color, requires very low or no O2
commonly seen in vacuum packages

Question 53

oxymyglobin

Answer 53

occurs when O2 is bound to the 6th binding site
myoglobin has a very high affinity for O2, when meat is exposed to O2 then its known as bloom = oxygenation
heme iron is FERROUS 2+
bright cherry red color
requires continuous exposure to O2, OMb penetration increases with exposure, not a stable formation, eventually promotes oxidation

Question 54

metmyoglobin

Answer 54

oxidation of ferrous to ferric (loss of electron) brown or tan color
forms because of insufficient oxygen, depletion of electrons, contamination (aerobic bacteria)
MMb formation is gradual, located between internal DMb and superficial Omb, gradually thickens and moves to surface

Question 55

where does metmyoglobin form

Answer 55

formation of metmyoglobin layer between deoxymyoglobin core and oxymyoglobin core and oxymyoglobin surface
during meat discoloration initial metmyoglobin formation occurs on subsurface

Question 56

metmyoglobin reduction

Answer 56

reduction of MMb to DMB is CRITICAL, muscle continuously uses electrons b/c electrons necessary to keep heme iron FERROUS

Question 57

Metmyoglobin reduction steps

Answer 57

1. OMb to MMb, (switch to ferric iron) low O2
2. MMb to DMb, formation of DMb dependent on O2 scavenging enzymes & reducing enzymes, both are depleted postmortem

Question 58

what is a muscles ability to transition termed

Answer 58

metmyoglobin reducing ability, varies by muscle, PM age, pH, temp, etc

Question 59

carboxymyoglobin

Answer 59

formed when DMb exposed to CO, not a naturally occurring reaction, myoglobin has a higher affinity for CO than O2
heme iron is ferrous Fe++, formats a stable red color, stability depends on CO availability
CO is approved for use in meat packaging systems at 0.4%, initial concern for “spoilage masking”

Question 60

carboxymyglobin

Answer 60

COMb is visually indistinguishable from Omb, CO inhibits pathogenic bacteria growth, CO inhibits lipid oxidation –> promotes desirable, CO promotes color, but doesn’t inhibit natural spoilage process, odor of fresh meat is equally important as color