Exam 4 Flashcards
meat quality factors
tenderness
juiciness
flavor
color
odor
3 most important factors for palatability
Flavor (taste and aroma) * most important
tenderness
juiciness
meat palatability
Tenderness is essential for consumer acceptance
90% of US steaks are considered tender or very tender
recent studies suggest flavor is equally important
when tenderness is within an acceptable range, then flavor becomes MORE important to eating satisfaction
58% of consumers indicate flavor has more impact than tenderness
43% of consumers indicate tenderness has more impact than juiciness
Is tenderness influenced by marbling?
only 10% of the variation in tenderness is associated with the marbling “halo effect”
Meat tenderness
tenderness is essential for consumer acceptance
tenderness is one of the few variables that add value
what influences tenderness
contractile state of the muscle: shorter sarcomere length=tougher
enzymatic degradation: calpain protease system
connective tissue:
marbling: higher marbling=more tender
marbling and the halo effect
only 10% of the variation in tenderness is explained by marbling
marbling helps to lubricate the mouth and reduce the density
at least 2% marbling is needed for acceptable tenderness
flavor perception
flavor is based on perception not sensation: combo of taste and aroma
taste: perceived by taste buds primarily on the tongue
odor/aroma: detected by the olfactory system
greatest contributor to perceived flavor
low molecular weight volatile compounds bind to olfactory receptors and are responsible for perceived flavors
basic tastes in meat
sweet
sour
bitter
salty
umami
odor/aroma in meat
raw meat has little aroma and has a blood-like flavor
however raw meat is a reservoir of precursor compounds that develop into flavor and odor-causing compounds as a result of chemical reaction that occur during cooking
cooked meat flavors
stem from:
the Maillard reaction, which combines amines and sugars to produce “meaty” flavor
thermal oxidation of lipids during cooking which produces volatiles/aromatics accounting for species flavor difference
volatiles produced during cooking that contributes to meat flavor
compounds formed in mailard reaction: aldehydes pyrazines
compounds formed during lipid thermal oxidation: alcohols aldehydes, hydrocarbons, ketones
amount composition of IM fat affects flavor profile of meat
IM lipids and associated volatiles produced during cooking are primary contributors to the flavor and aroma of meat
animal production practices that affect meat flavor do so primarily via effects on amount of composition of IM fat
effect of marbling degree on the palatability of a positive sensory experience
the higher the marbling the more likely a positive sensory experience
grain finishing for 100 days
produces grain-fed beef flavor
increase beef flavor, decrease fishy, decrease milky-oily
pre-harvest stress can influence flavor
important to avoid stress associated with handling and transport prior to harvest
compared to normal beef, dark cutting beef has a less desirable flavor with a higher incidence of off-flavors often characterized as:
bloody/serum like, sour, bitter, soapy
PSE pork tends to have an acidic flavor
Forage-finished beef affects on beef fat composition
higher levels of omega-3 polyunsaturated fatty acids, C 18:1 trans fatty acids, and stearic acid
all of which are negatively correlated with flavor desirability
flavor often characterized as grassy, gamey, livery, milky/oily, or fishy
Grain-finished beef affects on beef fat composition
higher levels of oleic acid, linoleic acid, and other monounsaturated fatty acids
all of which are positively correlated with flavor desirability
desired before fat flavor often characterized as “buttery”
Other factors affecting flavor
species: red meat and poultry
breed: bos indicus vs bos taurus
sex: androstenone, skatole
diet: grain fed vs grass fed
age: young lamb vs mutton
packaging: MAP, over-wrap, vacuum
fat
muscle
aging
enhancement
cooking method
Meat Quality
tenderness
juiciness
flavor
odor
color
multiple processes deteriorate these properties: bacterial, chemical, enzymatic, and physical activity
maintenance of these desirable properties= shelf life
meat discoloration
meat discolors much before it spoils
the best indicator of spoilage is smell
importance of meat color
consumer base purchasing decisions off od meat color: more important than any other factor
color is an indicator of freshness or wholesomeness: if not bright cherry red may be perceived as spoiled or unwholesome
discoloration influences meat purchases: at 20% discoloration discrimination by consumers, at 40% discoloration rejection by consumers
discoloration influences meat purchase: 15% of retail beef is discounted due to discoloration, and annual revenue loss >3.7 billion
importance of meat color continued
color plays a large role in determining retail case life:
consumers consider bright red/pink to be desireable, deviations may create unacceptability
consumers determine quality through appearance
discoloration is considered unwholesome
many biochemical, physical, and microbiological factors affect color: understanding causes for discoloration helps with management of color
utilization of tools to maximize retail case life
how is meat color measured
CIE L, a, and b* values
hue: trueness of red; arctangent (b/a)
chroma: intensity or degree of color saturation; (a^2 + b^2)^1/2
subjective color measurements: how the individual eye perceives color, trained or consumer panels
L*
lightness (z axis: 0-100)
greater L* = lighter sample
lower L*= darker sample
a*
redness (x-axis; +60 to - 60)
greater a* means more red
b*
yellowness (Y axis; +60 to -60)
greater b* means more yellow the sample
myoglobin
sarcoplasmic protein
primary protein responsible for meat color
contain 8 alpha helies and a prosthetic group
water soluble and contains protein and non protein portions: non protein heme ring, protein globin
heme ring of myoglobin
centrally located Fe that can for 6 bonds:
4 bonds with pyrrole nitrogen
5th bond with proximal histidine (amino acid portion of globin)
6th binding site can reversibly bind ligands and other compounds
nature of the group attached to the 6th binding site & 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 valance (charge) of Fe
when reduced (ferrous, 2+) myoglobin readily binds oxygen or H2O
the valance state of Fe depends on availability of electrons: ETC, enzymes use residual O2 long after harvest
ferrous vs ferric
ferrous= reduced
ferric= oxidized
chemical forms of myoglobin
primary forms of myoglobin:
deoxymyoglobin (DMb)
oxymyoglobin (OMb)
metmyoglobin (MMb)
carboxymyoglobin (COMb)
deoxymyoglobin
occurs when H2O or no ligand is available for binding to 6th site
heme iron is ferrous (Fe2+)
publish-red or purplish-pink color
requires very low or no oxygen: commonly seen in vacuum packages
oxymyoglobin
occcurs when O2 is bound to the 6th binding site: myoblgoin has very high affinity for O2
bloom= oxygenation
heme iron is ferrous (Fe2+): same valance state as BMb (no change in electrons
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 (Fe2+) Mb to ferric (Fe3+): loss of an electron
resulting in brown or tan color: undesirable
why does MMb form
insufficient oxygen to form OMb
depletion of electrons
contamination (aerobic bacteria)
MMb formation is gradual: MMb located between internal DMb and superficial Omb, gradually thickens and moves to surface
