meat science exam 4 Flashcards
what country eats the most meat?
US, Brazil, Canada, UK, China
what is the read meat vs poultry consumption trend?
reduced red meat intake but increased poultry consumption
long term beef consumption trend
consumption for all types of beef steadily declined over the long term
American’s red meat trend
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”
males vs female meat poultry egg consumption
male above average vs females marginally below recommended
vegtable consumption
overall very below recommended
trends for america eating less red meat (most - least)
health reasons, other meats seem healthier, limiting cholesterol/fat, too expensive, farming concern, eating more plant-based,
obesity rate trends
obesity rates have increased during the same time
caloric consumption trends
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
todays meat lean & nutrien
todays meat supply is leaner &nutrien dense, beef external fat has decreased 80% in past 20 yrs
lean red meat accessibility to public
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
todays pork
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
ground beef shifts
there are ongoing shifts to leaner ground beef
red meat nutrients
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)
unintended consequences of inadequate meat consumption (vit/min)
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
unintended consequences of inadequate meeat consumption (sarcopenia)
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
benefits of fats found in meat
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
fatty acid profile of beef
50% monounsaturated fatty acids, polyunsaturated fatty acids 4%, majority is unsaturated (better than saturated)
fatty acid profile of pork
50% monounsaturated fatty acids, polyunsaturated fatty acids 11%
salmon benefits
omega-3, 35 times and 47 times as much omega-3 as does grass or grain finished beef respectively
red meat diet studies
20+ randomized control trials consistenty show healthy diets with 4-6oz lean red meat improves
cholesterol, blood pressure, weight management
overall meat summary
Increase of diabetes heart disease obesity but increase in protein consumption and decrease in red meat, not correlated
5 things that drive meat quality
tenderness, juiciness, flavor, color, odor
3 driving attributes of palatability
flavor > tenderness > juiciness
meat palatability
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
met tenderness
tenderness is essential for consumer acceptance, tenderness is one of few variables that ADDS VALUE
what influences tenderness
contractile state of the muscle (sarcomere length) enzymatic degradation of proteins, connective tissue, marbling
marbling and halo effect
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”
flavor perception
flavor is based on perception not sensation = combination of taste and aroma
what is taste vs odor perceived/detected by
taste is perceived by taste buds primarily on the tongue vs odor/aroma is detected by the olfactory system
odor/aroma
greatest contributor to perceived flavor, low molecular weight volatile compounds bind to olfactory receptors and are responsible for perceived flavors
what are basic taste in meat (food in general)
sweet, sour, bitter, salty, umami
odor/aroma in meat
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
Maillard reaction
basic cooked meat flavor system which combines amines and sugars to produce a “meaty” flavored: bake things to get golden brown/toast
amount and composition of IM fat affects the flavor profile of meat
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
grain-finishedbeef
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
pre-harvest stress influences flavor
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
forage finished beef
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
grain-finished beef
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
factors affecting flavor
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
what processes deteriorate meat quality
bacterial, chemical, enzymatic, physical
shelf life definition
maintenance of desirable properties (tenderness, juiciness, flavor, odor, COLOR)
Importance of meat color
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
meat color discoloration acceptability
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
how is meat color measured
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
myoglobin
primary protein responsible for meat color, contains 8 aloha helices and a prosthetic group
water soluble and contains protein and non-protein portions
heme ring
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
chemical state of iron
color influenced by compounds that interact with Fe in the heme ring
ability to bind with myoglobin depends on what
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
the valence state of Fe depends on
availability of electrons, ETC, enzymes use residual O2 long after harvest
chemical form of myoglobin
primary forms of myoglobin = deoxymyoglobin,, oxymyoglobin, metmyoglobin, carboxymyoglobin
deoxymyoglobin
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
oxymyglobin
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
metmyoglobin
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
where does metmyoglobin form
formation of metmyoglobin layer between deoxymyoglobin core and oxymyoglobin core and oxymyoglobin surface
during meat discoloration initial metmyoglobin formation occurs on subsurface
metmyoglobin reduction
reduction of MMb to DMB is CRITICAL, muscle continuously uses electrons b/c electrons necessary to keep heme iron FERROUS
Metmyoglobin reduction steps
- OMb to MMb, (switch to ferric iron) low O2
- MMb to DMb, formation of DMb dependent on O2 scavenging enzymes & reducing enzymes, both are depleted postmortem
what is a muscles ability to transition termed
metmyoglobin reducing ability, varies by muscle, PM age, pH, temp, etc
carboxymyoglobin
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”
carboxymyglobin
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
