Arch. Geflügelk. 2002, 66 (6), 274 – 279, ISSN 0003-9098. Verlag Eugen Ulmer GmbH & Co., Stuttgart
The functional properties of muscles
from force fed Mulard ducks.
2. The thermal properties of muscle proteins.
Funktionelle Eigenschaften der Muskeln von zwangsgefütterten Mulardenten.
2. Thermische Eigenschaften der Muskelproteine
Janina Wołoszyn1
Manuskript eingegangen am 14. November 2001, angenommen am 9. Februar 2002
Introduction
The texture, appearance and flavour of meat are changed
during heat treatment. The most intense changes in meat
during heating are due to changes in muscle proteins. The
important process induced by heat is thermal denaturation
of muscle proteins a process which initiates various other
molecular processes as e.g. protein to protein aggregations
(Stabursvik and Martens, 1980). Differential scanning
calorimetry (DSC) is a thermo-analytical technique for
monitoring changes in physical or chemical state and
properties of materials as a function of temperature, by detecting the heat changes associated with such processes. In
meat technology the DSC technique can monitor phase
transitions and chemical reactions occuring within a muscle and can be successfully applied to measuring thermal
transitions or denaturation temperatures of proteins (Kijowski and Mast, 1988; Kijowski, 1989). The most commonly specified parameters are onset temperature, temperature of maximum peaks and enthalpy changes. In the
DSC the heat denaturation of a protein is detected by an
endothermal peak as a function of increasing sample temperature – a D.S.C. thermogram.
Information about the thermal stabilities of the major
muscle proteins at different pH and salt levels may
yield practical information with regard to meat processing. It is the basic information on individual muscle
proteins and their interactions. The DSC technique is
used for studies on the thermal transitions of proteins in
muscle tissue as well as in isolated muscles proteins.
The thermal characteristics of purified proteins often differ from those occurring in natural systems. It depends
on physiological state and pH of muscles, thermal stabilities of proteins, and kind of muscles (Wright et al.,
1977; Stabursvik et al., 1984; Kijowski, 1989; Synowiecki and Grabowska, 1984; Ndi and Brekke, 1992).
The addition of NaCl to the meat causes considerable
modifications of physicochemical features of myofibrillar
proteins, the fraction mainly responsible for meat quality. The effect of ions Cl on heat stability of myofibrillar proteins of different animals was monitored in
studies by Quinn et al. (1980), Stabursvik and Martens (1980), Wright and Wilding (1984), Kijowski
and Mast (1988a) using DSC technique.
1
Department of Animal Food Technology, University of Economics, Wrocław, Poland
The aim of this work was to characterize the thermal
properties of breast and leg muscles (raw meat and with
addition of 2.5% NaCl to meat) from force fed Mulard
ducks and drakes. The onset temperature (T0), maximum
thermal transition temperatures (Tmax) and denaturation
enthalpy (DH) were evaluated. These parameters can provide valuable information not only on the intrastinic stability of the protein, its internal bonding and structure, but
also on its process behaviour.
Materials and methods
The information on breed and age of Mulard ducks was
described, previously (Wołoszyn, 2002; Report 1). The
material for examination were the breast (BM) and leg
(LM) muscles cut out 24 h after killing from industrially
slaughtered male and female force fed ducks. In the present work 8 pieces of each kind of muscles were investigated. For each of the eight pieces of muscles three repetitions were made and the average values are presented in
tables.
The pH values of raw muscles regardless of sex were
5.70–5.97 (BM) and 6.02–6.22 (LM) and with addition of
2.5% NaCl 6.02–6.07 (BM) and 6.21–6.37 (LM), respectively.
The Seiko Instrument Inc. DSC 22 C Differential Scanning Calorimeter was used. The samples (app. 14.4–
19.9 mg) were taken from central part of Pectoralis Major
(PM) and Semitendinosus muscles (SE) and placed in DSC
hermetic aluminium pans. The hermetic capsule with distilled water was used as reference. Calibration of the instrument
was carried out with high purity metals (stannum, indium
and gallium) with accurately known melting point and enthalpy (stannum – DH ¼ 60.62 mJ mg1, Tm ¼ 232 C;
indium – DH ¼ 28.59 mJ mg1, Tm ¼ 156.6 C; gallium
– DH ¼ 80.17 mJ mg1, Tm ¼ 29.8 C). The heating conditions of samples were programmed and fully controlled by
microcomputer within the range of 30–90 C. The heating
rate (HR) amounted 3 /min for all samples. The analysis was
conducted according to the Operator’s Handbook – Seiko
Instr. DSC (1995).
Before statistical analysis gross errors were eliminated
in data. The T-Student’s test was used to establish significant differences between means of experimental results.
The statistical analysis was conducted with the application
of the SCIENTIST PC program.
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WOŁOSZYN, Functional properties of muscles from force fed Mulard ducks. 2. thermal properties
275
Figure 1. Thermal transitions of muscle (PM) proteins from Mulard ducks
Thermische Zustandsänderungen der Muskelproteine im Brustmuskel (PM) von Mulardenten
Results
The raw PM and SE muscles of both sexes exhibited a
complex thermogram with three major areas of endothermic transitions. The thermal curve covered nine peaks in
case of PM muscles (Figure 1). The first area with the
major peak at a maximum thermal transition temperature
of Tmax I ¼ 55.8 C was characteristic for both sexes (Table 1). In this area additional peaks for duck’s and (no
significant differences) for drake’s muscles were observed.
This area corresponded with the denaturation of myosin
and its subfragments and parts of sarcoplasmic proteins.
The thermal curve covered six peaks in case of SE musTable 1. Peaks in thermograms of PM muscles for ducks and
drakes
Peak-Temperaturen des Brustmuskels von Enten und Erpeln
Tmax
Peak number
Duck
Drake
t-Test
I
1
2
3
4
5
6
7
8
9
55.8
58.0
61.0
62.5
64.0
66.4
67.7
72.8
76.8
55.8
57.8
60.9
62.9
64.0
66.1
69.7
72.0
76.7
0.000
0.241
0.104
0.487
0.000
0.306
3.703*
0.898
0.121
II
III
* – significant difference between means (P < 0.05)
Archiv für Geflügelkunde 6/2002
cles (Figure 2). The first area was displayed only as one
peak for both sexes (Table 2). The second area was recognized as the sarcoplasmic and connective tissue proteins
denaturation. There were no significant differences between Tmax II for both sexes. The third areas of the thermograms were assigned to actin denaturation (no significant differences for both kinds of muscles and sexes). It
was stated that most differences in thermal transition of
the PM muscle proteins in comparison with the SE muscle
proteins were in the first area which corresponded to the
denaturation of myosin and its subfragments and parts of
sarcoplasmic proteins. In this area, not only the additional
peaks were observed for PM muscles but significant differences in values of Tmax I of the major peaks of the PM
and SE muscles, as well.
Table 2. Peaks in thermograms of SE muscles for ducks and
drakes
Peak-Temperaturen des Schenkelmuskels von Enten und Erpeln
Tmax
Peak number
Duck
Drake
t-Test
I
II
1
2
3
4
5
6
58.7
66.2
67.8
70.3
71.2
76.7
58.7
65.5
67.4
70.0
71.4
76.0
0.000
2.163*
0.421
0.341
0.221
0.636
III
* – significant difference between means (P < 0.05)
276
WOŁOSZYN, Functional properties of muscles from force fed Mulard ducks. 2. thermal properties
Figure 2. Thermal transitions of muscle (SE) proteins from Mulard ducks
Thermische Zustandsänderungen der Muskelproteine im Schenkelmuskel (SE) von Mulardenten
A higher onset temperature (T0) of the first transition
was observed for SE muscles of both sexes than for PM
ones. Furthermore, regardless of sex the denaturation enthalpy for the SE muscle proteins was significantly higher
than for the PM ones (Table 3). All these differences may
as well result from different contents of connective tissues
and different heat stability of breast and leg muscle proteins. The various thermal stability between red and white
muscles is ascribed to a different contribution of each subfragments of myosin in these muscles, what previously
was shown by Wu (1969), Lowey and Risby (1971) and
Pelloni-Müller et al. (1976).
The addition of 2.5% NaCl to meat reduced the number
of peaks on thermograms of both kinds of muscles. The
major peak and three additional peaks (which corresponded to denaturation of myosin and its subfragments
and parts of sarcoplasmic proteins) in case of the PM raw
muscles were reduced to one peak with Tmax I ¼ 51.9 C
for ducks and with Tmax I ¼ 52.7 C for drakes, after addition of NaCl to the meat. However, the addition of NaCl
to meat caused a decrease in the value of Tmax I from
58.7 C (for both sexes) to values of 55.1 C for duck’s
and 55.4 C for drake’s SE muscles. In the second area
(corresponding to denaturation of sarcoplasmic and connective tissue proteins) the number of peaks was reduced
to one with Tmax II ¼ 66.9 C, 67.3 C for the PM duck’s
and drake’s muscles, and 68.7 C, 68.9 C for the SE
muscles, respectively. The third area (denaturation of actin) was characterized by lower values of Tmax III, as well.
They were decreased from 76.8 C (duck PM), 76.7 C
(drake PM), 76.7 C (duck SE), 76.0 C (drake SE) to values of 71.4 C, 72.1 C, 73.2 C, 72.9 C, respectively
(Figure 3). The addition of NaCl caused the decrease of
the onset temperature of transitions. At the same time with
Table 3. Onset temperatures (T0) and total denaturation enthalpy (DH)
Anfangstemperaturen (T0) und gesamte Denaturierungenthalpie (DH)
Parameter
T0 [ C]
T0 [ C] with NaCl
DH [ J/g protein]
DH [ J/g protein] with NaCl
Duck
Drake
PM
SE
t-Test
47.9
42.5
14.5
10.9
49.6
47.1
18.8
13.3
2.173
3.167
3.468
2.683
(*)
(*)
(*)
(*)
PM
SE
t-Test
48.3
43.4
13.4
9.8
51.8
46.2
18.7
13.1
2.576*
3.178*
2.871*
2.717*
* – significant difference between means (P < 0.05)
Archiv für Geflügelkunde 6/2002
WOŁOSZYN, Functional properties of muscles from force fed Mulard ducks. 2. thermal properties
277
Figure 3. Thermal transitions of muscle (PM and SE) proteins from Mulard ducks (with 2.5% NaCl)
Thermische Zustandsänderungen der Muskelproteine in Brust- und Schenkelmuskeln (PM und SE) von Mulardenten (mit Zusatz von
2.5% NaCl)
KAP, KAN ¼ PM and SE Duck; KRP, KRN ¼ PM and SE Drake
lower maximum thermal transition temperatures a significant decrease in the total enthalpy occurred (Table 3).
Also, treating muscles with NaCl decreased heat stability
of myosin and actin. A higher onset temperature of the
first transition was observed for the SE muscle of proteins
of both sexes, as well as a significantly higher total denaturation enthaply in comparison with the PM muscle proteins, as in the case of muscles without NaCl.
Disscusion
The own results which present thermal transitions of
force fed duck PM and SE muscle proteins of both sexes
indicate three major areas of these transitions with different numbers of peaks. Previously, the DSC method was
used for analysis on the thermal transitions of proteins in
muscle tissue of rabbit (Wright et al., 1977; Wright
and Wilding, 1984), beef (Stabursvik and Martens,
1980; Quinn et al., 1980; Findlay and Stanley, 1984;
Wagner and Anon, 1985), pork (Stabursvik et al.,
1984), chicken (Kijowski and Mast 1988), turkey
(Trziszka et al., 1995; Popiel et al., 1997), goose (Popiel et al., 1997). The published thermograms of muscle
tissues of different animals generally had three major distinguishable peaks (52–60 C – myosin and its subfragments, 63–70 C – sarcoplasmic and connective tissue
proteins, 70–80 C – actin), but they vary greatly in details. The interpretations of the peaks also vary. The
probable causes of differences in muscle tissue thermograms and their interpretations may be: pH of muscles,
Archiv für Geflügelkunde 6/2002
contents of connective tissue, type of muscle (red/white,
mammalian/avian), rates of heating, and kind and susceptibility of the instrument used.
In own results, a higher onset temperature (T0) of the
first transition for SE muscles was observed for both
sexes. Furthermore, it was found that regardless of sex the
denaturation enthalpy for the SE muscle proteins was significantly higher than for the PM ones. The same regularity was stated by Kijowski and Mast (1988) for chicken
muscle and skin proteins. Chicken breast and leg muscle
proteins started to denaturate at lower temperatures than
skin proteins. The enthalpy to induce denaturation of skin
collagen was significantly higher than that necessary for
denaturation muscle proteins. Findlay and Stanley
(1984) observed, that the total enthalpy to induce denaturation of beef muscle semimembraneosus proteins was
higher than for denaturation muscle psoas major proteins.
They suggested that this may result from the different content of connective tissue.
In the present study a destabilizing effect of NaCl on
duck muscle proteins by reduction of the number of peaks
on thermograms and by lowering the Tmax and the total
enthalpy of denaturation was stated. The destabilizing effect of Cl ions on myofibrillar proteins was observed in
previous studies with purified proteins from rabbit and
beef muscles (Wright et al., 1977; Stabursvik and Martens, 1980; Wright and Wilding, 1984), and with beef,
rabbit, pork and chicken muscle tissue (Quinn et al.,
1980; Kijowski and Mast, 1988a), too. They observed in
their studies that the typical thermogram which consisted
of a few peaks was severely reduced to one or two peaks.
278
WOŁOSZYN, Functional properties of muscles from force fed Mulard ducks. 2. thermal properties
The presence of Cl ions dramatically altered the heat
stability of proteins by lowering the temperature of denaturation and total enthalpy of thermal transitions. Salt
can decrease the heat stability of the muscle proteins, so
that they denature and coagulate at lower temperature.
According to the suggestions of Von Hippel and
Schleich (1969) binding the ion Cl (from NaCl) to potentially active sites on a protein causes displacement of
the water molecules which stabilize protein structures.
Thus, there is a presumably competition between water
molecules and added neutral salts for the potential binding sites causing a lowering of temperature as well as
energy of denaturation. This phenomenon can be very
important for the poultry processing industry (Kijowski
and Mast, 1988a).
In conclusion, the PM and SE muscles from force fed
Mulard ducks exhibited a complex thermogram with
three major endothermic transitions. The SE muscle proteins required more heat energy to denature compared to
the PM muscles. This indicated that the PM muscle proteins were more sensitive to the thermal process than the
SE ones. The process of heat treatment for breast muscle’s products may require to conduct in a lower final
temperature than leg muscle’s products. The addition of
2.5% NaCl to meat decreased the onset temperature, the
maximum thermal transition temperatures and total denaturation enthalpy. This means, that the force fed duck
muscle’s products which incorporate salts will require
lower final temperature than products with no salt, but
no lower temperature than needed to preserve products
free from the bacterials.
Zusammenfassung
Funktionelle Eigenschaften der Muskeln von zwangsgefütterten Mulardenten. 2. Thermische Eigenschaften der Muskelproteine
Bei zwangsgefütterten Mularden wurden die thermischen Eigenschaften von Brust- (Pectoralis Major – PM) und Schenkelmuskeln (Semitendinosus – SE) für beide Geschlechter untersucht.
Ferner wurde auch die Auswirkungen einer Zugabe von 2.5%
NaCl zu Muskeln anaylsiert. Hierzu wurde die Differential-Scanning-Kalorimetrietechnik (DSC) eingesetzt. Die Anfangs- (T0)
und Maximaltemperaturen (Tmax) der thermischen Zustandsänderungen und der gesamten Denaturierungsenthalpie (DH) wurden
bestimmt. An Hand der Thermogramme der Brust- und Schenkelmuskeln wurden drei Bereiche endothermer Veränderungen
beobachtet. Der erste Bereich der Zustandsänderungen (ein
Hauptpeak und drei zusätzlich Peaks für Brustmuskeln – PM;
nur ein Peak für die Schenkelmuskeln – SE) korrespondierte
mit der Denaturierung von Myosin, seiner Subfragmente und eines Teils der sarkoplasmatischen Proteine. Der zweite Bereich
(vier Peaks bei beiden Muskelpartien und bei beiden Geschlechtern) korrespondierte mit der Denaturierung der sarkoplasmatischen Proteine und der Proteine des Bindegewebes. Der dritte
Bereich (ein Peak bei beiden Muskelpartien und bei beiden Geschlechtern) wurde als die Denaturierung des Aktins identifiziert.
In diesen Untersuchungen wurden höhere T0 und DH-Werte für
Schenkelmuskeln (SE) im Vergleich zu Brustmuskeln (PM) bei
beiden Geschlechtern beobachtet. Die Zugabe von 2.5% NaCl
zu den Muskeln reduzierte die beobachtete Peakanzahl in den
Thermogrammen. Es wurde auch eine Reduzierung der To,
Tmax und DH-Werte festgestellt.
Stichworte
Summary
The thermal properties of breast (Pectoralis Major – PM)
and leg (Semitendinosus – SE) muscles from force fed
Mulard ducks of both sexes were investigated. The effects
of an addition of 2.5% of NaCl to meat on thermal properties of muscle proteins were investigated, too. In these
experiments the diferrential scanning calorimetry (DSC)
technique was used. The onset temperature (T0), maximum thermal transition temperatures (Tmax) and total denaturation enthalpy (DH) were evaluated. The breast and
leg muscles of both sexes exhibited complex thermograms
with three major endothermic transitions. The first area
(one major and three additional peaks for the PM muscles)
corresponded to the denaturation of myosin and its subfragments and parts of sarcoplasmic proteins. The first
area displayed only one peak in case of leg (SE) muscles.
The second area (four peaks for both kinds of muscles
and sexes) was assigned to sarcoplasmic and connective
tissue proteins denaturation. The third area (one peak for
both kinds of muscles and sexes) was recognized as the
actin denaturation. The higher onset temperature and total
denaturation enthalpy for leg (SE) than breast (PM) muscles of both sexes was observed. The addition of 2.5%
NaCl to meat caused a reduction in number of peaks on
the thermograms. A decrease of onset temperature, maximum thermal transition temperatures and total denaturation enthalpy was found, as well.
Keywords
Ducks, meat, muscles, differential scanning calorimetry,
thermal transition, protein, onset temperature, maximum
temperature, enthalpy
Ente, Muskeln, Differential-Scanning-Kalorimetrie, thermische
Zustandsänderung, Protein, Anfangstemperatur, Maximaltemperatur, Enthalpie
References
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Correspondence: Dr. Janina Wołoszyn, Department of Animal Food Technology,
University of Economics, Komandorska 118/120, 53–345 Wrocław, Poland; e-mail:
[email protected]
Buchbesprechung
Alles über Rassetauben, Band 6: Tümmlertauben,
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Erich Müller (Hrsg.), Alles über Rassetauben, Band 6
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