Available online at www.sciencedirect.com
MEAT
SCIENCE
Meat Science 77 (2007) 504–511
www.elsevier.com/locate/meatsci
Suitability of three commercially produced pig breeds in Germany for
a meat quality program with emphasis on drip loss and eating quality
Daniel Mörlein *, Gregor Link, Carsten Werner, Michael Wicke
Institute of Animal Breeding and Genetics, University of Göttingen, Albrecht-Thaer-Weg 3, D-37075 Göttingen, Germany
Received 24 October 2006; received in revised form 25 April 2007; accepted 30 April 2007
Abstract
This study aimed at characterising 606 crossbred pigs of three commercially available breed types in terms of their carcass and meat
quality. Breed G and H were German Large White (LW) · German Landrace (LR) sows sired with Pietrain (PI) boars, i.e.
PI · (LW · LR). Breed S was 25% Duroc (DU), i.e. PI · (DU · LR). Most of the parameters were affected by breed and/or date of
slaughter. The meat of crossbred pigs with 25% Duroc proportion appeared most favourable because of higher intramuscular fat content,
lower drip loss and higher sensory liking scores. Conductivity is closely related to drip loss while the data suggests that the relationship is
dependent on breed and carcass weight. The application of conductivity and lean meat yield thresholds to select carcasses with uniform
and superior meat quality effectively decreased drip loss and increased intramuscular fat content as well as sensory liking scores. The
variation of meat quality traits remains high, though.
2007 Elsevier Ltd. All rights reserved.
Keywords: Pork; Meat quality; Conductivity; Drip loss; Intramuscular fat; Duroc
1. Introduction
The attractiveness of pork to consumers is largely determined by appearance, i.e. colour, amount of marbling and
drip loss (Brewer & McKeith, 1999; Ngapo, Martin, &
Dransfield, 2007). Besides high food safety and good economic value, consumers desire reliable and satisfying palatability. The visual appearance is becoming even more
important due to the increasing share of pre-packed meat
for self-service. Since there is hardly communication about
the quality by sales personnel anymore, the product itself
and the package have to communicate the meat quality.
Although there are many other factors also influencing
the final meat quality, e.g. animal nutrition, transport, handling, stunning, etc. breed affects the quality traits to a
large extent (Armero et al., 1999; Blanchard, Warkup,
Ellis, Willis, & Avery, 1999; Fischer, Reichel, Lindner,
*
Corresponding author. Tel.: +49 551 395611; fax: +49 551 395587.
E-mail address: [email protected] (D. Mörlein).
0309-1740/$ - see front matter 2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.meatsci.2007.04.030
Wicke, & Branscheid, 2000; Josell, von Seth, & Tornberg,
2003). Thus, breed comparisons are performed quite often
when meat quality is an important consideration.
This study aimed at evaluating commercially raised
crossbred pigs of three breeding companies in terms of
their suitability for a meat quality program. Whereas two
crossbreds were of similar genetic origin, one included
25% Duroc. The research also intended to assess the variability of meat quality traits between the genotypes, the
incidence of PSE and the suitability of physical measurements to discriminate carcasses with superior meat. The
intramuscular fat content and drip loss were of specific
interest.
2. Materials and methods
2.1. Animals
This research included in total 606 castrated male and
female pigs originating from three commercially available
D. Mörlein et al. / Meat Science 77 (2007) 504–511
breed types. All animals were three way crosses with Pietrain (PI) as sire line. Breed G and H both were offsprings
of German Large White (LW) · German Landrace (LR)
sows sired with Pietrain (PI) boars, i.e. PI · (LW · LR).
Breed S included 25% Duroc (DU), i.e. PI · (DU · LR).
The pigs were raised at several commercial farms and they
were fed with standard pig diets. We did not collect data at
farm level, e.g. daily gain, feed consumption, etc. For each
breed the pigs were provided by at least two farms. The
companies were asked to deliver the pigs at about 95 kg
hot carcass weight. The pigs were slaughtered at a commercial abattoir within regular conditions (electrical stunning)
at six dates distributed within 1 year (2003: June 24; July
22; October 15; December 2; 2004: March 3; May 12).
Thus, we realised a nearly fully balanced design: six
dates · three breeds · two sexes. The carcasses for the
research were randomly selected at slaughter from the
batches that were delivered by each company.
2.2. Carcass traits and meat quality parameters
Slaughter weight, lean meat percentage, muscle and fat
thickness measures were recorded by the slaughter company using a Fat-O-Meat’er grading probe (SFK Technology GmbH). Early postmortem pH value of M. longissimus
dorsi (MLD) was measured on suspended carcasses in the
region of the 2nd/3rd last rib 45 min postmortem (pH 45)
prior to entering the chilling room without prior shock
cooling. The next day the chilled carcasses were transported to the packing plant. There, electrical conductivity
and pH were measured 24 h postmortem on suspended carcasses (EC24, pH 24). Conductivity and pH was recorded
with LF-star and pH-star instruments, respectively (Matthäus, D-04603 Klausa, Germany), in accordance with
Kauffman, Sybesma, Smulders, Eikelenboom, Engel, van
Laack, Hoving-Bolink, Sterrenburg, Nordheim, Walstra,
van der Wal (1993) and Altmann et al. (2005). Loins were
then detached from the carcass and cut across at the position of the 2nd/3rd last rib. At the chop surface that was
allowed to bloom for 10 min CIE-L, a, b colour values of
MLD were recorded in triplicate on non-overlapping sites
with a Minolta CR-300 chromameter (set at D65, 2 observation angle). The loins were then transported on ice to the
laboratory for further analysis. Sampling (position and
subsequent use of slices) is displayed in Fig. 1. Drip loss
1 2
3 4
of samples taken approximately 30 h postmortem was measured according to the bag-method (Honikel, 1998) after
48 h storage time at 4 C. Samples for chemical and sensory
analysis were vacuum packed and frozen at 20 C until
analysis. Prior to the analyses samples were thawed overnight at 4 C. From a cutlet without adjacent fat layer
the intramuscular fat was extracted using a Soxtec apparatus (Foss) and petrol ether with prior HCl pre-treatment
according to German Food Legislation (LFGB, 2005).
IMF values are given as percentage of fresh matter. For
determination of grill loss and shear force another sample
was cooked on a plate contact grill set at 180 C until the
internal temperature reached 73 C. Samples were then
allowed to cool down to about 22 C. Shear force measurements were performed perpendicular to the fibre direction
of at least six subsamples using an Instron 4130 material
testing machine equipped with a Warner-Bratzler-blade.
Crosshead speed was set to 200 mm/min. Sensory properties of 328 samples were determined by a six member
instructed panel using a 100 mm unstructured line scale
with marked end points. Besides tenderness, juiciness and
flavour as objective criteria, overall sensory impression
was evaluated (overall sensory liking score). Chops for sensory analysis were prepared with the contact grill as
described above and cut into cubical subsamples of about
1.5 cm edge size. Samples were served hot to the panelists
sitting in individual booths illuminated by sodium vapour
lamps to mask potentially occurring meat colour
differences.
2.3. Data analysis
Analysis of variance was performed with SAS PROC
MIXED (SAS version 9.13, SAS Institute, Cary USA).
The model included the fixed effects breed, sex, date of
slaughter and their interactions. Least squares means were
compared pair wise with the 0.05 level of significance. Relationships between parameters were examined by grouping
carcasses according to their pH and EC values within intervals. Pearsons product moment correlations between
parameters were calculated with SAS PROC CORR. Least
squares means between breeds after applying the quality
discrimination criteria were compared by one-way
ANOVA with breed as a fixed effect.
1 Drip loss
2 Chemical analysis
3 CIE-Lab colour
4 Cooking loss/shear force
5 Sensory analysis
5
Cranial end
505
Caudal end
2nd/3rd last rib
Fig. 1. Sampling scheme of Musculus longissimus for subsequent analyses. The loin was divided in cross-sections each 2.3 cm thick. Location and
corresponding use of the subsamples are shown.
506
D. Mörlein et al. / Meat Science 77 (2007) 504–511
Breed had a significant effect on most carcass traits and
meat quality parameters except back fat thickness, loin
area, pH 45 and muscle redness, respectively. Sex had significant effects on lean meat percentage and intramuscular
fat content. The effect of date of slaughter as well as the
interaction effect of breed and date of slaughter was highly
significant for all parameters with the exception of grill
loss.
3. Results and discussion
3.1. Carcass composition and meat quality traits
Mean and variability of parameters obtained are shown
in Table 1. Mean hot carcass weight was 94.9 ± 5.9 kg,
whereas lean meat yield was approximately 57.6% of hot
carcass weight. For meat quality indicating parameters
the variability of electrical conductivity was higher compared to pH 45 and pH 24. In fact, ultimate pH variability
was lowest of all parameters whereas yellowness (b*) variation was highest with the least due to the range of colour
values that also comprises negative values. For drip loss
the coefficient of variation was similar to EC24.
3.3. Breed comparison
3.2. Effects
For effects of breed, sex, date of slaughter and their
interactions, least squares means are shown in Table 2.
Table 1
Variation of carcass and meat quality traits (n = 606)
Trait
Mean
MIN
MAX
SD
CV
Carcass weight (kg)
Lean meat (%)
Muscle thickness (mm)
Back fat thickness (mm)
pH 45 min p.m.
pH 24 h p.m.
EC24 h p.m. (mS/cm)
Lightness L*
Redness a*
Yellowness b*
Drip loss (%)
94.91
57.59
63.92
15.00
6.42
5.53
6.24
47.35
8.06
0.14
6.37
77.00
50.10
42.70
8.00
5.70
4.73
2.40
38.76
4.73
3.05
1.28
113.40
64.20
79.90
22.80
7.20
6.28
14.10
60.26
11.28
5.11
16.08
5.87
2.66
5.10
2.61
0.22
0.15
2.32
2.74
1.05
1.02
2.52
6.19
4.62
7.97
17.42
3.45
2.66
37.25
5.79
13.02
742.82
39.58
Carcass weight of Breed H was lowest but this is suggested to be caused by the company delivering the pigs
rather than to be a breed effect. As for muscle thickness,
lean meat percentage and loin area, Breed G performed
best, followed by breed S and breed H.
In Fig. 2 the absolute frequency of measured IMF,
drip loss, EC24 and lightness L* values with relation to
breed are shown. Whereas nearly 40% of all analysed
samples do not reach 1% intramuscular fat content, only
20% of all samples contain more than 1.5% IMF. IMF
between 1.5 and 2.5 are widely regarded as optimal with
respect to eating quality and confirmed most recently
(Fortin, Robertson, & Tong, 2005). Comparing the
breeds, 50% of breed G pig’s IMF was below 1% in contrast to 20% of the breed S. Accordingly, the proportion
of breed S pigs with IMF above 1.25% was far higher
compared to the other breeds. Most probably this is
due to the 25% Duroc proportion in that crossbreed,
as Duroc is known for higher IMF contents (Armero
et al., 1999; Blanchard et al., 1999; Fischer et al., 2000;
van Laack, Stevens, & Stalder, 2001; Josell et al., 2003;
Wood et al., 2004).
Table 2
LS means and respective standard errors of selected traits dependent on breed and sex, respectively (n = 606, i.e. 202 each breed)
Trait
Breed G
PI · (LW · LR)
Breed H
PI · (LW · LR)
Breed S
PI · (DU · LR)
Castrates
Females
B
S
D
B*S B*D S*D B*S*D
Slaughter weight (kg)
Meat percentage (%)
Backfat thickness (mm)
Muscle thickness (mm)
LD muscle area (cm2)
L*
a*
b*
Intramuscular fat (%)
pH 45 min p.m.
pH 24 h p.m.
EC24 h p.m. (mS/cm)
Drip loss [%]
Cooking loss (%)
Shear force (N)
Sensory likingd
95.18b
58.20b
15.18
65.56b
54.80c
47.20a
8.02
0.12a
1.03a
6.43
5.56b
6.30b
6.38b
29.79a,b
47.84b
50.7b
93.51a
57.32a
14.99
62.58a
51.15a
48.00b
8.14
0.42c
1.20b
6.41
5.51b
5.86a
6.70b
30.15b
44.35a
51.0b
95.61b
57.41a
14.81
63.42a
52.34b
46.88a
7.95
0.07b
1.39c
6.42
5.53b
6.45b
5.92a
29.25a
45.52a
54.5a
94.67
(.29)
56.87a (.13)
15.83b (.13)
63.55
(.30)
51.35a (.30)
47.37
(.14)
8.10
(.06)
0.17
(.05)
1.32a (.02)
6.42
(.01)
5.54
(.01)
6.08
(.13)
6.43
(.13)
29.91
(.17)
45.98
(.70)
52.3
(0.9)
94.87
(.29)
58.43b (.13)
14.15a (.13)
64.16
(.30)
54.17b (.30)
47.35
(.14)
7.99
(.06)
0.08
(.05)
1.10b (.02)
6.42
(.01)
5.53
(.01)
6.33
(.13)
6.24
(.13)
29.55
(.17)
45.83
(.70)
51.8
(0.9)
***
***
ns
***
***
***
ns
***
***
ns
***
*
**
*
*
*
ns
***
***
*
***
ns
ns
ns
***
ns
ns
ns
ns
ns
ns
ns
***
***
***
***
***
***
***
***
***
***
***
***
***
ns
***
ns
ns
***
ns
ns
ns
*
ns
*
ns
ns
ns
ns
ns
**
ns
ns
(.36)
(.16)
(.16)
(.37)
(.37)
(.18)
(.07)
(.07)
(.29)
(.02)
(.01)
(.16)
(.15)
(.21)
(.86)
(1.1)
(.35)
(.15)
(.16)
(.37)
(.37)
(.17)
(.07)
(.07)
(.29)
(.02)
(.01)
(.16)
(.15)
(.21)
(.85)
(1.1)
(.36)
(.16)
(.17)
(.37)
(.37)
(.18)
(.07)
(.07)
(.30)
(.02)
(.01)
(.16)
(.16)
(.22)
(.88)
(1.1)
Significance of the effects breed (B), sex (S), date of slaughter (D) and their interactions is given.
***Effects are significant with p < 0.05 ( ), p < 0.01 ( ) and p < 0.001 (
*
**
***).
a,b,c
Different superscripts indicate significant differences between breeds and sexes, respectively (a < 0.05).
d
Sensory liking scores: 0 = worse . . . 100 = best.
***
***
***
***
***
***
***
***
***
***
***
***
***
ns
*
*
ns
**
***
ns
***
**
*
*
ns
ns
***
ns
*
*
ns
ns
*
*
ns
ns
**
ns
ns
ns
*
ns
*
ns
ns
ns
ns
ns
D. Mörlein et al. / Meat Science 77 (2007) 504–511
120
507
90
80
100
80
Frequency [n]
Frequency [n]
70
60
40
60
50
40
30
20
20
10
0
1.0
1.5
0
2.0
5
IMF [%]
7
9
11
Drip loss [%]
90
140
80
120
Frequency [n]
Frequency [n]
70
100
80
60
40
60
50
40
30
20
20
10
0
0
44
48
52
56
3
CIE L* Lightness
5
7
9
Electrical conductivity [mS/cm]
Fig. 2. Histograms of intramuscular fat values, drip loss, electrical conductivity 24 h p.m. and lightness L* with respect to breed (n = 606, i.e. 202 each
breed). Breeds are: , G: PI · (LW · LR); , H: PI · (LW · LR); , S: PI · (DU · LR).
For drip loss, breed S pigs had a markedly lower drip
loss compared to the other breeds (Table 2). This is in
accordance with earlier findings that pigs containing some
DU show less drip loss (Armero et al., 1999; Blanchard
et al., 1999; Fischer et al., 2000). We did not observe significant drip loss differences between the breeds G and H.
Though breed S yielded least drip loss, this breed
showed the highest conductivity values. Contrarily, the
mean drip loss in breed H was highest, whereas mean electrical conductivity value was lowest in breed H pigs (Table
2). Fig. 2 gives a breed comparison of EC value and drip
loss distribution. No significant differences between breeds
were found for pH 45 whereas little differences exist for pH
24. Fischer et al. (2000) and Armero et al. (1999) reported
significantly higher pH 45 of crossbreds containing Duroc
genes. Contrarily, Josell et al. (2003) found Duroc crossbreds having a lower pH 45. For colour measurements
there was no difference in redness between breeds, whereas
muscle lightness was significantly lower in breed S and G
compared to breed H. As for lightness variability, nearly
80% of all cutlet samples were between 44 and 50L* values
as can be seen in Fig. 2. Also the redness of muscle is rather
closely distributed (data not shown). Overall sensory liking
was significantly better for the breed containing Duroc.
This result supports the view that sensory liking is
increased with higher IMF content.
3.4. PSE incidence
Most often, pH and electrical conductivity are used as
indicators for pale, soft, exudative (=PSE) conditions of
the meat (Altmann et al., 2005; Josell et al., 2003; Warriss
et al., 1998). To check the discriminating abilities of these
indicating parameters, we applied two less or more strict
levels for each parameter as can be seen in Table 3. Accordingly, 0.5% and 2.3% of the carcasses are assumed to show
PSE when pH 45 < 5.8 and pH <6.0, respectively, are used
as threshold levels. However, applying EC24 values above
9 and 7 mS/cm, 15.3% and 32.0% of the samples, respectively, are PSE-like. To evaluate the indicative power of
EC24 and pH 45, drip loss was comparatively used as the
Table 3
Comparison of PSE incidence in percent with relation to the indicating
parameter, its threshold value, and breed, respectively
Conductivity 24 h p.m.
Drip loss
pH value
45 min p.m.
>7 mS/cm
>9 mS/cm
>7%
>9%
<5.8
<6.0
G: PI · (LW · LR)
H: PI · (LW · LR)
S: PI · (DU · LR)
32.2
25.3
38.6
12.4
11.4
22.3
35.6
39.6
30.7
15.8
17.3
10.4
0
1.0
0.5
1.0
2.0
3.7
Total
32.0
15.4
35.3
14.5
0.5
2.31
D. Mörlein et al. / Meat Science 77 (2007) 504–511
threshold parameter: saying 9% drip loss within 48 h postmortem is related to PSE, 14.5% of the carcasses showed
PSE conditions. Applying a more strict threshold of 7%
drip, 35.3% of the carcasses fell in the PSE class. Concluding from these corresponding results of both EC24 and drip
loss, about 30% of the carcasses ought to be classified as
PSE-like. Within a recent monitoring in six commercial
slaughter facilities in Germany that covered more than
20,000 carcasses (Altmann et al., 2005), the authors applied
the more strict EC24 values greater than 7 mS/cm. Dependent on the slaughter facility, they similarly concluded up
to 27% of the carcasses to show PSE – in accordance with
Warriss et al. (1998) for carcasses in the EU based on pH
values. Contrarily, Josell et al. (2003) also used the more
strict threshold pH 45 < 6.0 and found less than 6% of
the carcasses showing PSE conditions where the genotypes
did not include Pietrain. However, the assessment of EC
and subsequent evaluation of meat quality is dependent
on instrument types and set up, e.g. frequency (Lee et al.,
2000). In the present investigation the same instrument
was used by Altmann et al. (2005) suggesting the results
to be comparable. Comparing the breeds, breed S pigs
appeared inferior showing the highest percentage of PSE
meat concluded from conductivity measurements (Table
3). Contrarily, referring to a measured drip loss this breed
is rather superior. Recently, Duroc-sired pigs were reported
as being favourable in terms of PSE compared with Pietrain-sired pigs (Rauw, Varona, Raya, & Noguera, 2003).
Also Armero et al. (1999), Blanchard et al. (1999) and
Fischer et al. (2000) noted a lower drip loss for crossbreds
including Duroc proportions. In contrast to the present
results Rauw et al. (2003) found Duroc-sired pigs having
the lowest conductivity values 24 h postmortem.
3.5. Relationships between traits
Table 4 shows correlations between drip loss, conductivity, pH and colour, respectively, in relation to breed.
Among all traits under investigation, the relationship
between drip loss and electrical conductivity measured
24 h postmortem, EC24, is closest with slight differences
of the correlation coefficients between breeds. Colour measures are not as closely related to drip as is EC. Remarkable differences between breeds exist, though. Earlier,
muscle colour and drip loss were concluded to be rather
independent phenomena (van Laack et al., 1994). The correlation of both pre- and post-rigor pH, respectively, and
drip are comparably low.
H: PI x (LW x LR)
G: PI x (LW x LR)
S: PI x (DU x LR)
14
12
Drip loss [%]
508
10
8
6
4
2
--
<=3 3-4
4-5
5-6
6-7
7-8
8-9 9-10 10-1111-12 >12
--
Electrical conductivity class [mS/cm]
Fig. 3. Mean drip loss related to electrical conductivity of MLD with
relation to breed. The graphs represent mean values and standard errors of
drip loss of each EC class.
As shown above, breed S had the highest mean EC
value while drip loss was lowest compared to the other
breeds. Thus, the relationship is worth looking at more
explicitly. In Fig. 3 mean drip loss is displayed dependent
on EC class with respect to breed. Clearly, breed H
yielded higher drip loss at certain conductivity values
while breed S in comparison had significantly lower drip
loss, especially at higher EC values. To our knowledge
there is no similar finding.
Additionally we looked at the relationship between
slaughter weight, drip loss and EC as shown in Fig. 4.
EC is increasing not only with higher drip loss but also
with increasing slaughter weight. We suggest histo-morphological reasons. With increasing age, muscle fibre size
is increasing, while the fibre density, i.e. the number of
fibres per area is decreasing. Thus, less cell membranes
per cm electrical pathway act as electric insulators resulting
in higher conductivity values. This may in general explain
higher EC values with increasing slaughter weight. Most
recently Fischer, Lindner, Judas, and Höreth (2007)
reported significantly higher EC24 values of heavier pigs
compared to lighter pigs but with the same initial pH.
Though detailed data were not shown, Altmann et al.
(2005) reported increasing EC with increasing slaughter
weight concluding a worse meat quality. Besides the muscle
fibre effect described above, the prolonged cooling of heavier pigs may also contribute to higher EC values.
Table 4
Correlation (and p-level of significance) of selected traits and drip loss with respect to breed type
Breed
EC
All
G: PI · (LW · LR)
H: PI · (LW · LR)
S: PI · (DU · LR)
0.53
0.52
0.59
0.55
pH 45
(<.0001)
(<.0001)
(<.0001)
(<.0001)
0.25
0.20
0.29
0.25
L*
pH 24
(<.0001)
(0.0052)
(<.0001)
(0.0003)
0.25
0.34
0.25
0.16
(<.0001)
(<.0001)
(0.0004)
(0.0196)
0.42
0.32
0.51
0.36
a*
(<.0001)
(<.0001)
(<.0001)
(<.0001)
0.19
0.20
0.30
0.01
b*
(<.0001)
(0.0035)
(<.0001)
(0.8625)
0.43
0.43
0.50
0.30
(<.0001)
(<.0001)
(<.0001)
(<.0001)
D. Mörlein et al. / Meat Science 77 (2007) 504–511
Conductivity [mS/cm]
8
All breeds
Drip loss
< 5%
9
5-7%
> 7%
8
Conductivity [mS/cm]
9
7
6
5
4
3
2
1
0
G: PIx(LWxLR)
Drip loss
< 5%
<90
90-100
6
5
4
3
2
0
>100
<90
H: PIx(LWxLR)
Drip loss
< 5%
5-7%
90-100
>100
Carcass Weight [kg]
9
> 7%
S: PIx(DUxLR)
Drip loss
< 5%
5-7%
> 7%
8
Conductivity [mS/cm]
Conductivity [mS/cm]
> 7%
1
8
7
6
5
4
3
2
1
0
5-7%
7
Carcass Weight [kg]
9
509
7
6
5
4
3
2
1
<90
90-100
>100
0
Carcass weight [kg]
<90
90-100
>100
Carcass Weight [kg]
Fig. 4. Relationship between electrical conductivity, drip loss and carcass weight with respect to breed.
As for breed differences in the relationship of EC and
drip, breed S tended to have a greater fibre size (data not
shown). Contrarily, breed S had the highest IMF content.
On the one hand, fat has been shown to increase the electric
resistance (Altmann, Pliquett, Suess, & von Borell, 2004).
On the other hand, we assume breed S meat to have more
extracellular matrix (ECM) since IMF is associated with
the ECM. That ECM and IMF could also act as a physical
barrier against drip loss, i.e. trap the water. Comparing different lines, Gil et al. (2003) similarly found the lowest drip
loss in the line with the highest IMF content, whereas the
initial pH was not significantly different. This finding could
support our suggestion of a water trapping function of
ECM/IMF.
Since we currently do not have an explanation for the
contradictory observation of breed S having the highest
mean EC values but the least drip, the relationship of
breed, EC, weight, intramuscular fat content, water holding capacity and histological properties, respectively, has
to be looked at in future investigations.
For colour, lightness and yellowness increased with
higher drip loss and this relationship is closest in breed
H. As shown before, pre-rigor pH is not as suitable as
EC to estimate future drip loss since the correlations are
rather low (Table 4). In contrast to EC there is no such
breed dependence of the relationship between drip loss
and pH (data not shown). The results support earlier findings that electrical conductivity is a good predictor of drip
loss when measured 24 h postmortem (Lee et al., 2000).
3.6. Meat quality program
Lean meat percentage and conductivity values were
selected as criteria in order to select (a) more uniform carcasses with (b) more favourable meat quality, e.g. less drip
and more IMF. The criteria were chosen because of their
correlations and since they are rather easy to obtain at
Table 5
Mean values of carcass and meat quality traits before/after application of
EC and lean meat percentage cut-off values to discriminate carcasses with
improved meat quality
Trait
Original data,
i.e. no cut-off
Quality program criteria:
lean meat >54 < 59%,
EC24 < 7 mS/cm
Total
G
H
S
Program carcasses (%)
Slaughter weight (kg)
Meat percentage (%)
Electrical conductivity
(mS/cm)
IMF (%)
Drip loss (%)
Shear force (N)
Liking scoree
100
94.91
57.6
6.24
43.6
94.12
56.82
4.82
41.1d
95.2b
57.0b
5.04b
51.0d
92.7a
56.8a,b
4.87b
37.1d
94.9b
56.5a
4.48a
1.21
6.37
45.92
52.15
1.24
5.49
44.75
53.03
1.05a
5.47
46.4
51.3a
1.22b
5.68
44.2
51.6a
1.50c
5.19
43.8
56.3b
Breeds are G: PI · (LW · LR), H: PI · (LW · LR) and S: PI · (DU ·
LR).
a,b,c
Different superscripts indicate significant differences between breeds
(a < 0.05).
d
relative proportion within breed.
e
Sensory liking score: 0 = worse. . .100 = best.
510
D. Mörlein et al. / Meat Science 77 (2007) 504–511
14
2.4
12
2.0
IMF [%]
Drip loss [%]
10
8
6
1.6
1.2
4
0.8
2
0
0.4
G
G*
H
H*
S
S*
G
G*
Genotype
Median
25%-75%
5%-95%
Median
H*
S
S*
25%-75%
5%-95%
75
80
70
Sensory liking score
Shear Force FMax [N]
H
Genotype
60
50
40
30
20
65
55
45
35
25
G
Median
G*
H
H*
Genotype
25%-75%
S
S*
G
G*
H
H*
S
S*
Genotype
5%-95%
Median
25%-75%
5%-95%
Fig. 5. Variability of selected traits before and after application of threshold parameters to discriminate superior carcasses with respect to meat quality
(lean meat >54 < 59%, EC <7 mS/cm). Breeds are G: PI · (LW · LR), H: PI · (LW · LR) and S: PI · (DU · LR). Selected carcasses are indicated by (*).
slaughter. Conductivity measurements are faster and less
dangerous in terms of broken glass electrodes in pH measurements. The instruments are easier to maintain and to
calibrate compared to pH-meters. Table 5 shows the
results, i.e. yield of carcasses in percentage and corresponding traits, after application of the two cut-off criteria. Over
all breeds, a slight increase in IMF and remarkable
decrease of drip can be seen. However, the proportion of
carcasses that meet the program criteria is low: more than
50% were excluded by the thresholds. This is partly due to
breed S offspring because of the higher average EC values
as shown above. Only 37% of breed S carcasses meet the
criteria. Between breeds, breed S performed best showing
least drip, mean IMF around 1.50% and highest sensory
overall liking scores. These results support earlier findings
that higher IMF is related with higher sensory liking (Blanchard et al., 1999; Fernandez, Monin, Talmant, Mourot, &
Lebret, 1999; Fischer et al., 2000; Wood et al., 2004). Nevertheless a big variation of meat quality traits remains. In
Fig. 5 the variability of selected traits before and after
application of threshold parameters is depicted. Although
there is a quite effective reduction of drip loss, an increase
of IMF and of sensory liking, surprisingly the variation of
those parameters remains nearly unaffected. Since improv-
ing the product quality will increase both consumers’ willingness to purchase and the price they will pay as Platter
et al. (2005) found for beef, and further efforts have to be
made to advance the estimation of meat quality at slaughter. Ultrasound proved its potential for non-destructive
estimation of IMF of intact pig sides for further improvement of the carcass selection with superior palatability
(Mörlein, Rosner, Brand, Jenderka, & Wicke, 2005).
4. Conclusions
In this study we characterised currently marketed pigs of
three different genetic origins in terms of their carcass and
meat quality. Most of the parameters were affected by
breed and/or date of slaughter. Breed S pigs appeared most
favourable because of higher intramuscular fat content,
lower drip loss and higher sensory liking scores. Most
probably that is due to the 25% Duroc in that crossbreed
compared to 0% Duroc in the competitive crossbreds. Conductivity was closely related to drip loss while the data suggest that this relationship is dependent on breed and
slaughter weight. The application of conductivity and lean
meat yield cut-off thresholds to select carcasses with uniform and superior meat quality effectively decreases drip
D. Mörlein et al. / Meat Science 77 (2007) 504–511
loss and increases intramuscular fat content as well as sensory liking scores. The variation of meat quality traits
remains high, though. For establishing a meat quality program, careful consideration of crossbred and selection at
slaughter both to reduce the variability and to improve certain quality traits is recommended.
Acknowledgements
We gratefully acknowledge EDEKA Minden-Hannover
Holding GmbH for financial and practical support of this
investigation. We thank the staff at the Research Centre
of Animal Production and Technology in Vechta,
Germany for performing the laboratory analyses. D. Mörlein appreciates the fruitful discussion of the results with
K. Fischer (BfEL Kulmbach) and the comments of the
unknown reviewers.
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