meat tenderness Flashcards
how to describe carcass quality
lean
fat
bone
how to describe meat eating quality
tenderness
juiciness
flavour
how to describe nutritional quality
protein
fatty acids
minerals
other quality factors
spiritual quality
-halal, kosher
what is technological quality
functionality in processing application
what does technological quality start with
muscle physiology as modified by post mortem biochemical and structural changes and enzymatic activity
examples of technological quality
WHC, WBC = juiciness
what is meat
the muscle from an animal after going through rigor
rigor of a cattle
2 days
rigor of sheep/lamb
16 hrs
what happens during rigor mortis
significant, mechanical, physical, and biochemical changes occur
describe muscle tissue
highly ordered cellular structure that creates a fiber structure
how many proteins are in the fibrious structure of meat
3
what are the three proteins in fibrous structure of meat
sarcoplasmic proteins
connective tissue
myofibrillar protein
what are the main proteins that control tenderness
connective tissue
myofibrillar proteins
describe muscle structure
muscle->fibrils (fibre bundles)-> sacromere -> filaments
what does a sacromere consist of
actin and myosin filaments
name of three connective tissues/sheaths
endo, peri, epi
how do muscle contract in a dead animal
residual ATP + start anaerobic metabolism through glycolysis to produce pyruvate -> lactic acid
what does the thick fiilament consist of
myosin isoforms
what does the thin filament consist of
actin
troponin
tropomyosin
what protein do enzymes cut that result in improved tenderness during rigor
titin
what is rigor
stiffness
why is rigor muscle stiff
all sacromeres are contracted
where is the a band located
distance of thick filament (myosin)w
where is the I band located
inbetween the thick filaments
what band is shortened during contraction
I band
where is the z line
the zig zag of actin that runs vertical
role of connective tissue
reinforce muscle structure and support
-background toughness
what do fibre arrangement and physiological function affect and why
meat texture
different muscles have different functions, those that are more active have more connective tissue
most tender cuts
rib eye
prime ribs
sirloin
fillet
toughness of meat at ultimate pH
toughest it will get
what can be manipulated to promote enzyme breakdown
ultimate pH
what is the maximum shear force for meat to be acceptable
11
mechanism of tenderisation
calpains
protease enzymes that require tiny amounts of calcium to be activated
positive aspects on relying on subjective measurements
-human feedback: people that are consuming
-may show interlinked relationship
negative aspects of relying on subjective measurements
-inconsistent: depends on persons background
-training required
-expensive
-dependant on mood/psychological influence
what happens to test meat in destructive system
meat is cooked, cut and either sheared or compressed
how does a probe contact a sample in destructive systems
flat plunger
shearing jaws
tooth-shaped attachment
piercing rod
penetrating cone
requirements for a destructive system
a probe
a driving force
a sensing element
a read out system
forms of driving mechanisms in DS
weight and pulley
hydraullic system
drive electric motor
imparts motion at constant or variable rate
purpose of a sensing element
detects resistance
simple spring
strain gage transducer
purpose of a read out system
registers energy expenditure
-maximum force dial, oscillitator, electronic integrator
international method for meat tenderness
shear force
pounds of force required to shear 1/2 inch core of steak using warner-bratzler machine
-cooked at 160F and at least 8 1/2 inch cores
NZ way to measure shear force
kg force required to shear 1x1cm bite
-cooked at 75C and 8n replicates
shear values less than 5
very tender
shear values 5-8
tender
shear values 8-11
acceptable
shear values 12 and up
tough
define electrical stimulation
application of electricity to prevent excessive muscle contraction during onset of rigor mortis as a result of muscle shortening
experimental range of voltages
2.5-9000V
commercial stimulation range
low <150V: nervous system transfer the stimulus to muscles
high >1130: direct muscle stimulation
what happens during ES depending on parameters
vigourous muscle contraction with rapid pH decline
mechanisms to explain ES tenderising
-physical disruption of sacromeres = weaker fibres from severe contractions
-accelerated proteolysis due to increases activation of calpains
-increased temp = increased enzyme activity
tenderising effects of ES is best with
intermediate glycolysis
effect of Es on other meat quality traits
early ph decline post mortem -> affect enzymatic systems-> WHC, colour, stability, potentially antioxidative ensymes in muscles
concern for ES especially in large carcasses
increased drip loss from protein denaturation due to slow chill time
-fat insulated the heat energy produced during ES
physcial interventions used for meat tenderising
Electrical stimulation
high temperature conditioning
aging
mechanical tenderisation
wrapping
stretching
hydrodynamic pressure
ultrasound
what is high temp conditioning
holding meat above 5C to improve tenderess
optimal HTC conditions
14-18C, 10-48hrs
what happens above 25C
muscle shortening and decreased mu-calpain activity
-negative
mechanism for tenderising through HTC
reduction in muscle shortening
increased proteolysis through increased calpain and degradation of calpastatin
effect on other meat quality attributes
colour and colour stability: great colour early but doesnt last
decreased WHC through protein denaturation
mechanism for colour deteriation in HTC meat
higher temps mitochondria consume less o2, become leaky then release free radicals
what is aging
refrigerated storage of meat
mechanism of tenderisation through aging
allows endogenous proteases time to breakdown muscle structural proteins
enzymes involved in aging
mu-calpain
cathepsins
proteasomes
proteolytic enzymes from bacteria
optimal aging conditions
vacuum sealed
aging time depends on temp (high temp shorter time)
common range 17-19 but can be 2-61 days
effect on other quality attributes of aging
drip loss increase
cooking loss decrease
improved palatability
no effect on colour intensity or stability
what is mechanical tenderisation
applying force (compression or shear) causing deformation or damage to network of meat structural proteins
examples of mechanicla tenderisation
mallet: weakens integrity of myofribllar and connective tissues
blade: protein network and tissue are severed causing structure weakening
best conditions for MT
cold-boned BT-treated meat
BT is more beneficial for meat cuts with high levels of collagen
effect of MT on other attributes
reduced juicness
affect flavour dependant on cut
what is wrapping
wrapping muscles pre rigor with PET film to prevent mulscles shortening during rigor development
best wrapping conditions
used for hot boned meat when rapid chilling is required: prevent potential muscle contraction
-dependant on fibre organisation
other effects on wuality attributes from wrapping
appearnace: shape to the wrapped shape
what is stretching
aim to prevent muscle contraction by means of clamping, adding weights or manipulation of hanging methods
what is tender stretching
carcass is hung from pelvic bone instead of achillies tendon
what is tender cut
exploitation of the carcass weight to generate stretching on certain muscles
best stretching conditions
use of weights can reduce shear force by 30%
LT tenderness improves when stretched under fast chilling conditions but not slow
muscle location affects the tenderisation level acheived
effect of strecthing on other qualities
slightly decrease a* vlaues, drip and cooling loss (species dependant, doesnt happen in pork but does in beef)
what is hydrodynamic pressure
shockwave is passed thorugh the meat in fractions of a millisecond, a sudden increase in pressure is exerted on meat which results in disruption of mucle and connective tissue structures
best HDP conditions
tenderness improvement was largely dependant on quantity of explosive nad the numbre of detonations performed to meat sample
effect of HDP on other attributes
none reported
describe the use of ultrasound
mechinical vibrations at a frequency higher tan the range audible to human ear
mechanism of ultra sound
disrupt muscle fibres by altering the Z line structure anmd incfrease the lvel of cytosol clacium
best ultra sound conditions
24 khz, 12W/cm^2 for various times
effect of ultra sound on other qualitie
increased WHC
decrease yellowness
what is cold shortening
excess contraction or shortenign when meat is chilled too quickly
mechanisms
temp <10C
muscle still alive with lots of ATP
leaky sarcoplasmic reticulim, leaks Ca
calcium pump una bel to remove Ca
,uscle remains contracted
