S.Afr.J.Anim.Sci.9,I-g (1979)
THE EFFECT OF CHILLING TEMPERATURESAND MODE OF SUSPENSION
OF BEEF CARCASSESON SARCOMERELENGTH AND MEAT TENDERNESS
Receiptof MS 0+/,0-1978
J.H. Dreyer, A.J.J. van Rensburg, R.T. Naud6, P.J. Gouws and Suzette Stiemie
Animal and Dairy ScienceResemchInsttrute, Irene, 1675
(Key words:
Beef, carcass,meot, chilling, sarcomere,tenderness)
(Sleutelwoorde: Beeste,l<arkas,vleis,verkoeling,sarkomeer,sagtheid)
DII] INVLOEDVAN VERKOELINGSTEMPERATUUR
OPSOMMING..
EN HANGMETODE
VAN BEESKARKASSE
OP SARKO.
M E ER L EN G TEN
L S N Y WIIE R S TA V
NA
DN S P IE R E
J o n g A t r i k a n e r k r u i s r a s o s s cw a t o p o d / r b . v o e d i n g g e h o u i s t o t d a t d i e g e w e n s t eg e s k a t t ek a r k a s m a s s a s v a nl 2 0 e n
240kgbereik
was. rs in die pror'l' gebruik. Karkasse was in syc geskei - een groep sye het gedien as kontrole (hak-hangmetode) terwyl die eksperimentele syc aan dic pelvisbeengchang is en alber syc is aan een van vyl'verkoelingstemperature tussen 0o en 9oC blootgestel. Monsters vir sarkomeertellings en snyweerstand is gencenr van dic M. longissimus thoracis en die M" semitendinoss.
Sarkomeertellings was gemeet by
I 000 x vergroting en snyweerstand na gaarmaak by temperature van 600 en 80oC. Die 120 kg karkassehet vinniger verkoel en dus het
'n
hocr snyweerstand en korter sarkomere as die van 240 kg karkasse gehad. Die wyse van hang het 'n besliste effek op vleisdie spiere
'n
taaiheid gehad in soverre dat die pelvis-gehangdekarkasse se spiere laer snyweerstanden langer sarkomere gehad het, wat beskou kan
word as sagter vleis vir dic verbruikcr. Dic pelvis-hangmetodekan vir ten voUe geihtegreerdevleisfabrieke aanbeveelword maar nie in die
gcval u'aar karkassc vervoer moet word vir verwerking nie, Optimale aanvanklike verkoelingstemperatureten einde sagtevleis te verseker
r s v i r l i g l c ( 1 2 0 k g ) k a r k a s s ct u s s c n 7 o e n 9 o C e n v i r d i e s w a a r d e( 2 a 0 k g ) k a r k a s s et u s s € n3 0 e n 7 o C .
SUMMARY..
YoLrng Afrikaner crossbred steers were used for the experiment after being fed ad lib until a desired estimated carcassmass of
I 20 and 240 kg was reachcd- Carcasscswere split into sides - one group of sides served as controls (hock hanging method) while the
experimental sides were suspendedby the pelvicbone and both sides were subjected to one of hve chilling temperatures from 0o to 9oC.
Sampfc's for sarcomere counts and shear force determinations were taken from the M. longissimus thoracis and the M. semitendinoils.
S a r c o n t e r ec o u n t s w e r c t n a d e a t 1 0 0 0 x n r a g n i t i c a t i o na n d s h e a rf o r c e d e t e r m i n e d a f t e r c o o k i n g a t t e m p e r a t u r e so f 6 0 0 a n d 8 0 o C . T h e
m u s c l c s f r o n t c a r c a s s e st l l ' 1 2 0 k g h a d a g r c a t c r c h i l l i n g r a t c a n d a s a r e s u l t h a d a h i g h e r s h e a rf o r c e a n d s h o r t e r s a r c o m e r e st h a n t h e 2 4 0
k g c a r c a s s e sT. h e m o d e o l ' s u s p e n s i o nh a d a d c t l n i t e e f f e c t o n m e a t l e n d e r n c s si n t h a t t h e p e l v i c s u s p e n d e dc a r c a s s ehs a d a l o w e r s h e a r
force and longer sarcomereswhich could be interpreted as more tender mcat to the consumer. The pelvic method of suspensioncan be
recommended for fully ritegrated meat plants bul not for plants where carcasseshave to be transported for processing.Optimal initial
c h i l l i n g t e m p c r a t u r e s l b r l i g : h t c a r c a s s e s( 1 2 0 k g ) w e r c b e t w e e n 7 0 a n d 9 o C a n d f o r h e a v i e r c a r c a s s e s( 2 4 0 k g ) b e t w e e n 3 0 a n d 7 o C .
Meat quality can be influencedby a variety of
factors of which the influence of initial chilling temperature on the pre-rigor carcassis an important facet.
The musclemoving nto rigor mortis showsa decrease
in
extensibilityand can reactto a cold stimulusby shortening. This is reflected in a reduced sarcomerelength
(Locker, 1959) which in turn causesan increase
in fibre
diameter.Locker (1959) groupedthesesarcomerepatterns accordingto lengthsinto four types - wheretype
I is relaxed and type lV shows extreme shortening.
Through the actin-myosin involvement in sarcomere
is adversely
contractionmeat tenderness
affected(Marsh
& L e e t ,1 9 6 6 ) .
Locker (1959) statedthat on enteringigor inortis
some musclessuch as the M. psoasmaior are in a relaxed
condition whereasother muscleslike the M. longissimus
dorsi show a variety of contractionpatterns,from totdly relaxed to fully contracted over the length of the
samemuscle.He also establisheda relationshipbetween
thesesarcomereand musclecontractionpatternsranging
from zero to 80 per cent shorteningof the mtximum
length.
ln 1963, Locker and Hagyardfirst recognisedthe
effect of cold shorteningon the pre-rigor muscle.Not all
musclesare subject to this phenomenon,notably the
"red" musclesof the pig which are affected to a lesser
degree (Bendall, 1972). From this stage onward the
practical effect of cold shorteningon meat quality was
more fully appreciated.In the literature reviewed no
specific information however,was forthcoming on the
P rl v i r
C orcor mcr.
t2O kg
t -l l .
i rrri ttndi noru r
2-M.
lcngiri:mu3 tho
Shror forcr
Hock
-X
- Pclvij
IShoor forse
r---o
Sorcomrrc ,loagrlr-- Hock
O - - -o Sorcom.r. 'bngrh- polvit
|,r
o
o
a
't
J
-. t,-
o
o
3
a
o
I
s
o
;
L
o
o
J
(o
a
vt
2,O
7
I
3
tt
Chillieg
Fig' I
l.mp."oturr
( oC )
The effect of mode of suspensionand chilling temperature on shear
force and sarcomerelength of M.Longissimus thoracis(2 davsageingancl60oC cooking rcmperarure).
effect of variouslow chilling temperatureson sarcomere
length and .meat tendernessin different carcassmass
groups.However,Bouton.Harris,Shorthouse
and Baxter
(0o to I oC and I 50 to
(1913) used two temperatures
l6oC) in their mutton studiesand this represented
a
large gap in degreecentigrade.The presentstudy was
undertaken to assesswhether possible differencesin
sarcomere length and meat tendernessoccur when
employing a seriesof initial chilling temperatureson two
nrassgroups.
carcass
Materialand Methods
Forty young Afrikanercrossbred
steerswereused.
The animals were kept in feeding lots on ad lib. concentrate feeding until they reachedthe desiredmass.
Two groups were selected,one to yield carcasses
of
approximately120 kg and the other of 240 kg.
The captivebolt was employedfor stunningand
were split
after bleedingand eviscerationall carcasses
into sides.Thesesideswerekept in two speciallydesigned ident ic alch i l l i n gro o ms ,e a c ho f w h i c h can accommodate four sidesat the sametime. Sidesweresuspended in such a way that a streamof air movedoverall the
carcasses
in a similar nlanner. The three controllable
variablesin the cold room wereair temperature,
velocity
and humidity. The latter two parameterswere kept
with trade pracconstantin both roolrlsin accordance
tices in this country viz. air velocity at 0,75 m per
secondand relativehumidity at 95 per cent. The third
par am et erwas v a ri e db e tw e e n0 o , 3 o , 5 o , 7 0 and 9oC .
For a specificgroup of four carcasses
at a particular
were
of
suspended
in
temperaturethe two sides a carcass
- either the conventionalhock posidifferentp<-rsitions
tion or the pelvic position by hanging through the
obturator Jbramen (Fig. I ). Sideshangingin a similar
mannerwere groupedtogetherin one room. Both rooms
werekept at identicalchillingconditions.
The temperatureof the M. longissimusthoracis
(M.l.t.i and the M. semitendinows(lV. s/./ were continually monitored during the 48-hour chilling period
with thermocouples
insertedinto the musclesto a depth
of 3 cm. Following a 48-hourperiod in the chill room
was judged according
the fat cover of all carcasses
to a four point scale.After quarteringbetweenthe lOth
fat
and I lth ribs the thicknessof the subcutaneous
was measuredon the forequarter1,5 cm lateralto the
medial plane of the side. For the 120 and 240 kg carcassesrespectively,the mean values for the fat cover
were found to be 0,2 and 2,2 and for fat thicknessI,0
a n d7 , 7 m m .
Samples were taken from the light area of the
st.
M.
and
and the M.l.t. for sarcomeredeterminations
tendernessevaluation. According to the nrethod of
Hegartyand Naud6( 1970),suitablysizedsanrples
were
taken from the large specimens48 hours post slaughter,
homogenizedin distilled water in an Ultra-Turrax blender until the individual fibres were separatedwith aslittle
damageas possible,and mounted with a small pipette
on a glassslide. Under a Zeissphotomicroscopewith a
reinforced light source and a cameralucida attachment
giving a I 000 x magnification on a flat surface, 25
individual fibres were measuredfor sarcomerelength.
Over an accurately measureddistance of l0 cm the
per fibre were counted.
nuntberof sarcomeres
To diminish the effect of ageing,muscle samples
of approdmately 200 g each were taken 48 hours post
slaughterand were cooked in plastic bagsfor one hour
without any addition of water. Two water baths were
used, regulatedat 600 and 80oC. Core sampleswith a
diameterof l9 mm were then taken parallelto the fibre
length. A minimum of six determinationson every
cooked samplewas made on the WarnerBratzlershear
meter.
Resultsand Disctusions
Mode of suspension
Sarcomerelength
Locker ( 1959)developedthe I-lV type divisionof
wherethe typesrangefrom type l(3,7 to 2,4
sarcomeres
pm; relaxed)to type IV ( I ,5 to 0,7 gm, extremeshortening). Accordingto this groupingthe sarcomerelength of
position( 1,9to I ,7 pm)
theM.l./. in the hock suspended
"close
remainson the vergeof the
to contraction"pattern (Type III; 1,8 to 1,5 pm) for the temper at ur e
range from 0o to 9oC (Table I ). Hock suspension
compactsthe vertebraeof the lumbar and sacralregions
at their junction so allowing the musclesto contract
(Hostetler, Landmann, Link & Fitshugh, 1970). This
was illustratedby the mean sarcomere
length of 1,8pm
for hock suspensioncomparedto the relaxed 2,4 pm
sarcomerelength of the pelvic suspension.
The latter
constitutesa reversalof the former effect by not permitting the M.l./. to contractto the samedegreedue to
a straightening
of the spinal column (Hostetler,et al-,
l91O). The statistical differencewas also highly signif i c a n t( P < 0 , 0 1 ,T a b l e8 ) .
Accordingto Hostetler,Link, Landmannand Fitshugh ( 1972) the minimum sarcomerelength for intact
beef musclein hock suspended
carcasses
is approximately 2,0 pm. Thjs possiblyholds true for carcasses
in
For
kg,
of
200
kg.
carcasses
120
as
in
excess
of
this
length showeda meanof 1,8pm
experiment,sarcomere
for the M.l.t. This could be attributed to the lack of
a more completefat covering,asin heaviercarcasses,
and
the more rapid reactionto the cold stimulusof the lower
mass presentedto chilling (Parrish, Young, Miner &
A ndersen
,1973).
Table I
Sarcomerelength (Wn) of the M. longissimusthoracis
Chilling Temperature(oC)
Carcass
mass
Suspension
mode
0o
3o
5o
7o
go
1,7
1,8
1,9
1,8
1,9
(ke)
Hock
Mean
Mean(suspen(mass)
sion mode)
(both modes) (both masses)
1,8
2,1
120
Pelvis
2,1
2,3
2,4
2,5
?s
Hock
1,8
1,9
1,8
1,8
1,8
Pelvis
2,4
2,6
)s
2,5
2,5
)1
2,2
))
2,4
240
Mean(temperature)
2,0
'r)
2,4
Table 2
Sorcomerelength (prn) of the M. semitendinosus
ChilLingTemperature(oC)
Carcass
mass
Suspension
mode
0o
3o
5o
7o
go
Hock
1,8
1,0
2.0
2,1
J,O
Pelvis
2,1
2,3
2,4
2,5
2,5
Hock
1,9
1,9
2,0
2,0
2,0
Pelvis
){
1,6
') 'l
2,6
2,6
2.1
))
2,3
2,3
2,3
(ke)
Mean
Mean(suspen(mass)
sionmode)
(both modes) (both masses)
2,0
120
240
Mean(temperature)
The M. sr. did not reactto the effectsof the mode
of suspensionto the samedegreeas the M.l.t. but there
nonethelesswas a higruy significantdifference(P<0,01)
in sarcomerelengthbetweenthe two methods(Table8).
Thesefindings agreewith those of Josephand Connolly
(1977\ which also show the sameeffect of suspension
method on sarcomere length although no definite
statistical differences were indicated in their study.
Hostetler, Link, Landmann and Fitshugh( 1973) noted
that the M. st. is not a suitablemuscleto be usedfor
sarcomerestudies as it does not react favourably to
2,3
?s
methodsinducingextensionof the fibres.In the present
study however, the M. sr. reacted significantly to the
mode of suspensionas is recorded above. The mean
sarcomerelength in pelvic suspendedcarcasseswas
2,5 pm and in hock suspendedcarcasses
2,0 prm(Table
2).
For all temperaturesemployed the sarcomere
lengths in both muscleswere shorter in the hock than
as can be seenin Tables I and
in the pelvic suspension,
1
Table 3
Shearforce (kd of M. longissimusthoraciscooked at 6FC
ChillingTemperature(oC)
Carcass
mass
Suspension
mode
0o
3o
5o
7o
go
7 ,6 4
6,74
6As
3,64
3,46
(ke)
Hock
120
Mean
Mean(suspen(mass)
sionmode)
(both modes) (both masses)
4,95
4,68
Pelvis
4,54
4,09
3,85
2,93
3,43
Hock
5,83
4,74
3,23
3,76
4,03
Pelvis
3,83
3,93
2,64
3,12
3,60
5 ,4 6
4,87
4,M
3,36
3,63
240
3,87
M ean( t e m p e ra tu re )
3,60
Table 4
Shearforce (kS) of M. semitendinosuscooked at 6PC
ChillingTemperature(oC)
Car c as
mass
Suspension
mode
0o
3o
5o
7o
go
6,O',l
5 , 12
5,30
5,38
5,35
(ke)
Hock
120
Mean
Mean(suspen(mass)
sion mode)
(both modes) (both masses)
5,61
6,12
Pelvis
6 ,4 7
5,77
5 , 3I
5,04
5,29
Hock
6 ,6 0
5 , 75
5,83
4,96
5,74
Pelvis
6.ll
5,86
5,70
4,83
5,77
6.3t
5,63
5,54
5,05
5,54
240
5J2
M ean( t e m p e ra tu re )
Shearforce
(600 and 80oC)and
At both cookingtemperatures
(Tables
3 and 5) core
up to 7oC
at chillingtemperatures
samples from the M.l.t. were more tender from the
pelvic suspension
than from the hock position in spiteof
sarcomerelength differencesat all temperatures.More
tender meat can be expectedfrom muscleswith longer
sarcomeres(Herring, Cassens& Briskey, 1965), but
Hostetler,et al. (1972), on the other hand,postulated
that sarcomerelength alone is not a preciseindex of
5,62
variationsbetweenanimalsas numerousother
tenderness
factors must also be considered.These iue circumstances,however,when sarcomerelength can be primarily related to tendernesssuch as when a muscle is
excised pre-igor (Marsh & Leet, 1966, and Herring,
Cassens,Suess,Brumgardt & Briskey, 1967). MacBride
and Parrish(1977) felt that there is only a small relationship betweensarcomerelength and tendernessand
that the effect of myofibril fragmentationhas a greater
influenceon the tenderizationof agedmusclethan does
sarcomerelength.
Table 5
Shearforce (kg) of M.longissimusthoraciscooked at 8PC
Chilling Temperature(oC)
Carcass
mass
Suspension
mode
0o
30
50
7o
90
7,69
6,26
(ke)
Hock
15,79
13,47
ll,l0
r20
Mean
Mean(suspen(mass)
sion mode)
(both modes) (both masses)
10,06
9,35
Pelvis
9,80
9 ,59
7 ,86
5,33
6,60
Hock
1 3 ,1 5
1 0 ,29
9,68
6,34
6,82
Pelvis
6,56
6,90
5,60
4.96
6,84
I1 ,3 3
1 0 ,06
8,56
6,08
6,63
?40
7,71
M ean( t emp e ra tu re )
7.00
Table 6
cookedot 9PC
Shearforce (kS) of M. semitendinosus
ChiltingTemperature(oC)
Carcas
mass
(kg)
Suspension
mode
Hock
0o
30
50
7o
90
8,58
8,47
8,lJ
7,93
7, 6 6
Mean
Mean(suspen(mass)
sionmode)
(both modes) (both masses)
7,90
8,03
120
Pe l v i s
8 ,8 8
8 , 6' 1
7,58
7,1' l
7,16
Hock
8,37
7 ,90
7 ,7|
6,57
7 ,65
Pe l v i s
7 ,7 2
7 . 56
7.36
6.54
7,26
8,39
8,15
7 ,l |
7,05
7 ,43
7,46
240
Mean(temperature)
7,59
suspension
on the shearforce values.
In this study the effect of ageingwas defiberately
minimized by using the samples at two days post
slaughter.
TemPerature
Whilst the mode of suspensionin the caseof the
l/.sr. had a definite effect on sarcomerelengthit showed
no effect on the shear force (Tables4 and 6). Table 8
illustrates no statistical significancefor the values of
this muscle.By comparisonJosephand Connony(977)
found a slight but significant effect of the mode of
to cool to l9oC at
The time taken by carcasses
various chilling temperaturesare recorded in Table 7.
which also had the
As expected the 240 kg carcasses
greater fat coveringhad a slower cooling rate than the
leaner I l0 kg carcasses.The different cooling rates
shown betweenthe two musclesare due to their respective anatomicpositions.
Table 7
Time lapse(h)post mortem to reachl}oC
Chilling temperature(oC)
Carcass Muscle
mass(kg)
0o
30
5o
7o
go
M. st.
9,60 10,25 12,00 15,18 21,72
M.l.t.
5,23 5,63 6,00 7,83 10,38
of 600 and 80oC. The effect of OoCchilling temperature
on the M.l.t. differed hiehly significantly (P<0,01)
from the effect at 50, 70 and 9oC (Table 8). As the
sarcomerelengths were also shorter at this temperature
and as sarcomerelength is purported to be linked to
tendemess(Hening, et al., 1965, and Hostetler,et al.,
1972) a higher shear force can be expectedat OoC,as
indeed was the case.The shearforce value of the M.l.t.
at 3oC also differed from that at 7oC and 9oC (Table
8) even though no statistically significant differences
in sarcomerelengths at these temperatureswere found.
r20
M. st.
13,49 16,31 I9,25 27,15 43,00
240
M.l.t.
8,34
9,04 I I ,13 14,35 19,63
Sarcomerelengths
The valuesobtained for sarcomerelengthsof the
M.l.t. as well as the M. st. at OoCwere different from
readingsat 30, 50, 7o and 9oC. Therefore,at OoC
sarcomerelengthsare shorterthan at the other upward
rangingtemperatures(Tables I and 2). No actual differencesin sarcomerelengthswere noted from 30 to
9oC ( T able7) .
Chilling rate had a seriouseffect on meat texture
when applied too rapidly in the pre-rigor condition
before muscle pH has dropped below 6,2 (Bendall,
1972). Accordingto Locker and Hagyard(1963) maximum musclecontractionof 48 per cent occursat OoC
and betweenl40 to lgoC thereis a very smallreaction
( < 10 per c en t). In te rp re ta ti o no f s a rc o m e re
l ength/
temperaturerelationshipwould be lesscomplicatedif
sarconrerelength, within limits, respondedin an orderly
or decreases,
but this
manner to temperatureincreases
would be biologicallyimprobable.In this study it was
found that sarcomerelength was at its shortestat OoC
but between the range of 30 to 9oC no statistically
significant differencesin sarcomerelength could be
( T a b l e8 ).
es t ablis hed
ln the M. sr. the same pattern occurred in the
s€ns€that the shear force value at OoC differed from
those at 30, 50, Jo and 9oC. Accordingto Hostetler
et al. (1973) the M. sf. is preferredfor studieson sarcomere lengthsand tendernesson account of its optimal
orientation of fibresbut they found this musclenot very
sensitiveto experimentaltreatments.The findingsof the
presentstudy are therefore in agreementwith those of
the latter authors.The evenmorphology could have its
advantagein the lower variability within the muscle and
this is illustratedby the lower coefficientsof variationin
the M. st. (5 to l5 per cent) ascomparedto thoseof the
llt.l.t.(8 to 35 per cent).
Findings in this experiment were tlrat while the
M.l.t. reactedvery differently to the two cooking temperatures(600 and 80oC) by almostdoublingits toughnessfrom one temperatureto the other (Tables3 and 5),
the M. s/. did not reactto nearly the sameextent. While
the M. s/. tended to have a higher shearresistancethan
the M.l-t. at 60oC it wason par or slightly lower at 80oC
cooking temperature(Tables4 and 6). Differencesin
connectivetissue content and composition were most
probably the contributing factors to this discrepancyin
shearforce valuesbetweenthe two musclesat different
cooking temperatures.According to the results of
Boccard, Naud6, Cronj6, Smit, Venter & Rossouw
( 1978),the collagencontent of theM. st. in young bulls
and steerswas 88 per cent higherthan that found in the
M.l.t.
Mass
Hos t et leer t a l . (1 9 7 0 )s ta te dth a t i t i s th e quanti ty
of actomyosin formed and not so much sarcomere
lengththat will havean influenceon tendernessln 1972
Hostetler et al. also establishedthat sarcomerelength
contributesonly l2 per cent to the variationin tendernessbetweenmuscles.This can explainlhe reasonwhy
sarcomeresappear to be in the relaxed state while the
degreeof toughshearforce valuesindicate a reasonable
nes s .
Shearforce
In Tables 3 to 6 the mean shearforce valuesfor
the M.l.t. andM. st. are given for cooking temperatures
Sarcomerelengths
Massdid not affect sarcomerelength in the case
of the tr[.1.t.(Table 8). The M. st., however,showedan
interactionbetweenmassx suspension
and whjle mass
had no effect on sarcomerelength in the vertical
suspendedcarcass,the sarcomerevalueswere greaterin
than in the 120 kg carcasses
the 240 kg carcasses
in
the case of pelvic suspension.Table 8 shows a highly
significantinteractionof massx suspension
in sarcomere
length for the M. st. which is most probably due to
the reducedeffect of chilling on the 240 kg carcasses
with the totally relaxed sarcomerepattem (2,5 prm).
Shes force
Conclusions
The effect of longer sarcomerelength can be
related to the shear force values.The readingsof the
M.l.t. showeda 4 : 5 kg ratio in favourof the 240 kg
carcassesat a cooking temperatureof 60oC while at
80oC cookingtemperature,the ratio was8 : 9 kg alsoin
(Tables3 and 5). Cooking
favour of the 240 kg carcasses
temperaturehad a very pronouncedinfluencein the case
of the M.l.t. where it doubled in shearforce resistance
from 4 to 8 kg. With the M. st. the differencewas not
as markedas it differedat a ratio of 6 : 8 between600
and 80oC. (Tables4 and 6.) Therewas no statistically
signi{icanteffect of massfor M. st. values.Giles(1969)
(600 and
studiedthe effect of two cookingtemperatures
70oC) on four beef musclesand could not detectany
significanteffectsof the treatmenton the ultra-structure
of the fibres. He found. however,that with heatingto
70oC the myofibrils were disruptedto a greaterextent
showeda very
than at 60oC and that the sarcomeres
not ic eables ho rte n i n ga t 7 0 o C . C o n tra c ti o nof the
with heat treatmentcould well influencethe
sarcomeres
of a particularmuscle.
shearforce resistance
Observationsin this experiment showed that
carcasses
with a low mass,due to its greaterchilling rate,
have higher shear force and shorter sarcomerelength
valuesof their musclesthan carcasses
with a larsermass.
As initial chilling temperaturewas increasedfrom
0o to 9oC so the shear force decreasedfor both the
M. longissimum thoracis and the M. semitendinosus
while no significant changesin sarcomerelength were
noted betweenchilling temperaturesof 3oC and 9oC.
The sensitivityof sarcomere
length to lower initial chilling temperaturesseemedto be lessthan that reflected
in muscletoughening.
Method of suspension
hasa pronouncedeffect on
meat toughness
in that the musclesfrom pelvicsuspendhave a lower resistance
ed carcasses
to shearingand have
longer sarcomeres.
The favourableeffect of pelvic suspensionon shearforce valuesand sarcomerelength,as
factors affecting tenderness,can be given consideration
plants whereall the stages
in integratedmeat processing
Table 8
Analysesof varianceof sucomere length ( Wn) and shearforce ( kg) valuesof two beef musc'les
-oC )
L.S .D .(Tentperature
F-V al ues
I
E
o
()
o
(/)
-.
s
U)
V)
Vt
Parameter
\q
i:
(,t
.t
tr
C
.I
t/,
20.9
c(t
F
Sggx
(-J
:
X
r\A
V\JH
xxx
l '
Sarcomere
8.48
length
l , 5 l 3 , 3 9 2 2 6 , 6 9I , 3 5 1 , 5 8 0 , 5 3 0 , 3 1
*
{.*.
Shearforce 3 2,6l
( 60oc )
6,18 6.t4
S hearf o rc e 3 5 .0 1
,s .9 9 8 ,8 6
t
**
t<
t8.41 1,35 2,26 I,65 0,59
:F*
rF*
*rF
**
*t
,F*
,Ftl.
t<*
*1(
,F*
oo
s
\
(80oc)
Sarcomere
length
\
t
5,51
Shearforce I 5,I 3
(6ooc)
{<*
2 0 .88 0.92 0.00 2.58 0.06
1 5 , 7 1J , 5 9 3 2 8,62 3,2622,09 0,18 0,47 * *
**
d.*
*
**
* (*
l,ll
4,50
**
*
l( rk
* r< * ' F
0,00 0.60 0,44 0,29 0,29
!
d
S hearf orc e 15 ,9 2
( 8ooc )
* P< 0 , 0 5
* * P< 0 . 0 1
4 , 1 73 , 0 3
**
l,2J 0,470,020,080,30
**
*c*
t(
*t<
*
from slaughteringto final processingis carried out under
the same roof. The superior quality of the final product
Due to the unusualshapeof
will merit this change-over.
tlrc post igor carcassfollowing this method of suspenin
sion it would not be practical to use these carcasses
non-intergratedplants should transport be involved.
It can be concluded that chilling temperatures
from 0o to 5oC can have a marked shorteningand
and
tougheningeffect on musclesof the lighter carcasses
that temperaturesbetween 70 and 9oC will be more
effectivein avoidingthis problem.The heaviercarcasses,
through the advantageof massand fat covering, can be
chilled at temperaturesfrom 30 to 7oC without any
seriousdetrimentaleffect on tenderness.
Acknowledgements
Thanks are due to Messn C.J. Visserand G. Smit
of the C.S.I.R. for control over all aspectsof chilling,
Dr H. van der Made of the V.R.I. for experimentalcontrol, Dr D. Viser of the A.D.S.R.I. for helpful suggestions on the script and Miss M.C. Smit and Mr HJ.
Venter also of the A.D.S.R.I. for technical assistance.
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