Properties of a Mixed Carrageenan-Gelatin Gel

J. Home Econ. Jpn. Vol. 45 No. 3 203-210 (1994)

Yoko ICHIKAWA, Keiko KUMENO, * Hiro AKABANE * * and Nobuko NAKAHAMA *

Kawamura Junior College, Toshima-ku, Tokyo 171, Japan * Faculty of Home Economics,Japan Women's University, Bunkyo-ku, Tokyo 112, Japan * * Kantogakuin Women's Junior College,Kanazawa-ku, Yokohama236, Japan

The concentration dependence of the rheological properties were investigated for simple gels

of ƒÈ-carrageenan (C) and gelatin (G) in concentration ranges of 0.45-0.9% (w/v) and 2-4% (w/v),

respectively. Mixed carrageenan-gelatin gels of various mixing ratios were prepared, i.e., C-G

(3 :1), C-G (1:1) and C-G (1:3), and the effects of mixing ratio were examined by measuring the rupture properties, dynamic viscoelasticity values and melting temperature. The temperature dependence of the simple gels and mixed gels was also determined.

The mixed gels generally exhibited hindrance toward gelation. The melting temperature of carrageenan gels had high concentration dependence, that of the mixed gels being nearly equal

to the equivalent simple carrageenan gel. The rupture stress, rupture energy and dynamic visco- elastic constants showed temperature dependence above 20•Ž, while they tended to remain con-

stant or slightly increase because of entropic behavior below 15•Ž.

(Received January 26, 1993)

Keywords : ƒÈ-carrageenan, gelatin, mixed gel, rupture property, dynamic viscoelasticity, apparent activation energy.

added to a specific gelling agent to make up for INTRODUCTION certain deficiencies and to obtain different textual

Carrageenan, which is extracted from red sea- properties. The rheological properties and mech- weed, is a polysaccharide like agar, and is classified anism for the gelation of mixed gels such as poly- into ƒÈ, ƒÇ and ƒÉ types as regards its structure. In saccharide-gelatin,10)-21) gum22)23) and two-phase carrageenan gels, a double 1) or single 2) helix dispersed systems 19) have recently been widely structure of linked molecules first combine and studied. The effect of mixing temperature on the form a cross-linked area, before further combining hardness of mixed gelatin-agar gels has been ex- to form a three-dimensional network structure.3) amined by Yasumatsu et al.,10) while the relation-

K-carrageenan is known to form a firm and rigid. ship between the mixing ratio of gelatin-agar and the properties of the gels has also been reviewed gel in the presence of particle cations such as po- tassium.4)-7) In gelatin gels, the triple helix by Shintani et al.11) Moritaka et al.1) have studied structure forms a cross-linked area.8) Since the the rheological properties of mixed agarose-gelatin

crosslinks in gelatin are relatively weak, the melt- gels at a high concentration, and Kobayashi et al.17)

ing temperature of a gelatin gel is correspondingly have reported that the rheological properties of

low. Gelatin gel can be swallowed easily, and has mixed K-carrageenan-gelatin gels differed signifi-

a good mouth feel, but it melts at room tempera- cantly from those of mixed agar-gelatin gels. The

ture. Both carrageenan and gelatin form gels that rheological properties of a mixed sol and gels such

are thermally reversible.9) as commercial carrageenan-gelatin preparations 20)

It is well known that other gelling agents or and ƒÈ-carrageenan-gelatin that has been differ-

non-gelling hydrocolloids such as gum can be ently treated 21) have been studied by Kawamura et al.

* * Present addres: Faculty of Home Economics, Japan Although ƒÈ-carrageenan is being widely utilized Women's University, Bunkyo-ku, Tokyo 112, Japan as a useful gelling agent in the food industry,

( 203 ) 1 J. Home Econ. Jpn. Vol. 45 No. 3 (1994)

Table 1. Volume fraction of the mixed gels

1) C, 0.9% carrageenan (w/v) ; G, 4% gelatin (w/v).

forming a characteristic gel after adding gelatin, Mixed carrageenan and gelatin gels of various

the mechanism for gelation and the temperature volume fractions were prepared from the foregoing

dependence of the rheological properties for mixed carrageenan and gelatin solutions by mixing at

carrageenan-gelatin gels have not been clarified. 65•Ž. The mixed solution was then poured into

In this study, we investigated the changes in the cylindrical glass cells in the same manner as that

rheological properties and melting temperature of for a simple gel. The volume fractions of the

mixed ƒÈ-carrageenan-gelatin gels at various vol- mixed gels are shown in Table 1, the abbreviations

ume fractions, together with the relationships be- used in this table being used hereafter.

tween the data for simple gels and the temperature Measurements

dependence of the rheological properties of these 1. Rupture25)-28)

gels. The rupture stress-strain curves were mainly obtained with a Dynagraph (IPC-134A I'TECH- MATERIALS AND METHODS NO Co.) at 10•Ž. The temperature dependence

Sample Preparation of the rupture stress for the gels was measured at

CS-88 ic-carrageenan (San'ei Chemical Co.) and 5 to 40•Ž after maintaining at each temperature

A-U alkali-treated gelatin (Miyagi Chemical Co.) for 1 h.

were used. The concentration of the carrageenan 2. Dynamic viscoelasticity 29)

gel was 0.9% (w/v) and that of the gelatin gel was The dynamic viscoelasticity data were obtained 4% (w/v). These concentrations were adopted so by measuring the longitudinal vibration at 2.0 Hz

that the rupture stress of both the simple gels was of a cylindrical gel (initial addition of a 1-g weight,

nearly equal. A 0.675% (w/v) and 0.45% (w/v) amplitude of •}100 ƒÊm) with a Rheolograph-Gel

carrageenan gel concentration and 3% (w/v) and instrument (CV-100, Toyo Seiki Co.). Storage

2% (w/v) gelatin gel concentration were also used modulus E', loss modulus E" and loss tangent

to evaluate the content effect of each gelling agent tan 3(=E"/E') were then derived. The temperature

in the mixed gels. However, it proved impos- for measurement was mainly 10•Ž, with 5-40•Ž

sible to evaluate a 0.25% (w/v) carrageenan gel being used to evaluate the temperature dependence.

and 1% (w/v) gelatin gel because the concentra- 3. Melting temperature

tion was too low for gelation. Simple carrageenan The melting temperature was determined by

and gelatin gels were prepared 24) by heating a using a computer-controlled water bath (Taiyo Ka-

carrageenan solution to 95-99•Ž and a gelatin gaku Kogyo Co.). A 5-ml sample solution was solution to 65•Ž in a round-bottom flask with a poured into a small test tube (1.3 cm in diameter, reflux condenser. Each solution was then poured 10 cm in height) and stored for 18 h at 10•Ž. The into cylindrical glass cells and held for 18 h at up-ended test tube was then immersed in the water

10•Ž. The sample dimensions were 3.0 cm in bath while raising the temperature at a constant rate diameter and 2.0 cm in height for the rupture of 0.5•Ž/min (20-60•Ž). The temperature at which measurement, and 2.0 cm in diameter and 3.0 cm the gel dropped rapidly from the bottom of the in height for the dynamic viscoelasticity measure- tube during heating was judged to be the melting ment. temperature.

2 ( 204 ) Properties of a Mixed Carrageenan-Gelatin Gel

Fig. 2. Rupture strain (ƒÃi) of the mixed gels.

Fig. 1. Concentration dependence of the rupture stress (Pf) of simple carrageenan and gelatin gels : G, gelatin gel; C, carrageenan gel.

RESULTS AND DISCUSSION

Rheological Properties of the Simple Gels

1. Rupture

The concentration dependence of the rupture stress (Pf) for the simple carrageenan and gelatin gels on a log-log graph is shown in Fig. 1. The rupture stress increased markedly from a concentration of 3% with the gelatin gel, and from 0.675% Fig. 3. Rupture stress (Pf) of the mixed gels : •œmixed with the carrageenan gel, the resulting gels becom- gel, •¢ carrageenan gel, •£ gelatin gel. ing difficult to break above these concentrations.

The rupture strain values for the carrageenan tion increased. It is assumed for a simple com-

gels in the range of 0.45-0.9% (w/v) and for the ponent system that the number of molecules in the

gelatin gels in the range of 2-4% (w/v) were 0.35- gel network increased as the concentration increas- 0.42 and 0.59-0.67, respectively. These figures ed, resulting in crosslinks with adjacent molecules,

confirm that the rupture strain of the gelatin gels and that the network structure then grew exponen- was much larger than that of the carrageenan gels. tially more dense.

2. Dynamic viscoelasticity The E' values for carrageenan were larger than Storage modulus E' values for the 0.45, 0.675 those for gelatin. It is suggested that the carra- and 0.9% (w/v) carrageenan gels were 0.43 •~ 103, geenan gels were more resistant to small deforma- 3.55 •~ 103 and 8.33 •~ 103 N/m2, and those for the tion, although the gel concentrations had been 2, 3 and 4% (w/v) gelatin gels were 0.29 •~ 103, adjusted so that the rupture stress values were

1.91 •~ 103 and 3.32 •~ 103 N/m2, respectively. Loss nearly equal. modulus E" values for the 0.45, 0.675 and 0.9% Rheological Properties of the Mixed Gels

(w/v) carrageenan gels were 1.99 •~ 102, 7.08 •~ 102 1. Rupture and 19.02 •~ 102 N/m2, respectively. The rupture strain of the mixed gels is shown

Although a truly linear relationship between in Fig. 2 when classified into the following groups: the logarithms of these values and the concentra- CG (3:1) resembling a carrageenan gel, C-G tion was not apparent, the dynamic viscoelasticity (1:3) resembling a gelatin gel, and C-G (1:1) values for the two simple gels, except for E" of the having intermediate properties between those of

gelatin gels, markedly increased as the concentra- the two simple gels. Compared with the simple

( 205 ) 3 J. Home Econ. Jpn. Vol. 45 No. 3 (1994) because these concentrations were too low for gelation. The rupture energy shows a similar trend to that of the rupture stress (Fig. 4). By mixing carrageenan and gelatin, the gels became easy to fracture, the C-G (3:1) gel having a particularly low value in all of the rupture properties. Kobayashi et al.17) have reported that a C-G (3:1) gel had the minimum value in rupture properties for a higher concentration than that used in this study, e.g., a 1% carrageenan-5.5% gelatin mixed gel. In spite of this difference in concentration, the results of this study are similar to those reported by Kobayashi et al.17) The C-G Fig. 4. Rupture energy (En) of the mixed gels. (1 : 3) gel had high values of rupture stress and rupture energy, and a similar value of rupture strain to that of the simple gelatin gel (G1). 2. Dynamic viscoelasticity The dynamic viscoelasticity values for the mixed gels on a semilogarithmic graph are shown in Fig. 5. The C-G (1 :3) gel in its elastic element (E') and the C-G (1:1) gel in its viscous element (E") were detected as inflection points. Further from these mixing ratios, the mixed gels exhibit the characteristics of an increasing content of gelling agent. Kobayashi at al.17) have examined the relationship between storage modulus E' of the dispersed particles (carrageenan or gelatin) and that of the continuous medium (gelatin or carrageenan) according to Okano's formula.31) They reported that there was no agreement with the experimental Fig. 5. Storage modulus (E') and loss modulus (E") values, which were smaller than the calculated of the mixed gels. values for all the mixed gels. We attempted to examine the results in the same way, and it also gels (Cl and G1), the rupture stress in Fig. 3 of proved unsuitable to apply this formula directly the mixed gels remarkably decreased, although the to the mixed gels used in this study. concentration of the Cland G1 gels had been selected Clark et al.14) have studied the structural and so that their rupture stresses were nearly equal. mechanical properties of agar/gelatin co-gels and According to the weakest link hypothesis,30) the concluded that water partition between the two strength against fracture for a whole system is not components should be considered thoroughly in a the average value of all the constituents but the composite system. It seems necessary to examine value for the weakest. However, in this study, the suitability of Okano's formula concerning the the rupture stress of the C-G (1:1) mixed gel was concentration, mixing ratio and water partition of higher than that of the 2% gelatin gel, which was the gels. the minimum for the constituents of this system. 3. Melting temperature These results may suggest the participation of water The concentration dependence of the melting partition between the two constituents and some temperature for the simple gels is provided in degree of interaction between carrageenan and Table 2. The melting temperature of the gelatin gelatin. The 0.25% simple carrageenan gel and gels decreased slightly as the gelatin concentration 1% simple gelatin gel could not be evaluated decreased, whereas that of the carrageenan gels

4 ( 206 ) Properties of a Mixed Carrageenan-Gelatin Gel

Table 2. Melting temperature of the simple carrageenan and gelatin gels

Table 3. Melting temperature of the mixed gels

decreased much more as the carrageenan concen-

tration diminished. It might be considered that, Fig. 6. Temperature dependence of the rupture prop-

in heating a carrageenan gel, the weaker cross- erties of C-G (1 :1) and G1 gels: ef, rupture

links such as hydrogen bonds within the network strain; Pf, rupture stress, En, rupture energy; ○C1,△C-G(1:1),●G1. structure disappear first, the double helix which formed three-dimensional structure then begins to Temperature Dependence melt, and the whole gel finally melts as the fluidity 1. Rupture increases. However, when the gel concentration The temperature dependence of the rupture was low and the networks were sparse, it was im- properties for the C 1, C-G ( 1 : 1) and G1 gels is possible to maintain the form while losing only a shown in Fig. 6. The temperature dependence of few crosslinks, and the gels melted easily. Since the rupture strain is hardly apparent, although it the crosslinks in the gelatin were far weaker than decreases in all three gels as the temperature in- those in the polysaccharide and collapsed rapidly creases the rupture stress and the rupture energy. at 28-30•Ž, the melting temperature of the gelatin This indicates that the gels would have lower

gels was less dependent on the quantity of gelatin values for the rupture properties toward their melt-

particles. ing temperature. This seems to be caused by The melting temperature of the mixed gels disappearance of the weaker crosslinks as the tem- provided in Table 3 are extremely close to those perature increases. of the simple carrageenan gels shown in Table 2. 2. Dynamic viscoelasticity It is suggested that gelatin, which is less concentra- The temperature dependence of the dynamic tion dependent and has a lower melting tempera- viscoelasticity values for the C 1, C-G (1:1) and ture, first loses its crosslinks and melts at around G 1 gels are shown in Figs. 7 and 8. Storage 29•Ž. The gel mixture is then confined by the modulus E' and loss modulus E" of all the gels carrageenan network structure until the whole gel tended to remain constant or slightly increase with collapses when residual carrageenan begins to melt initially increasing temperature, while the values as its own melting temperature is approached . dropped as the temperature was increased further. This phenomenon was also presumed from the Kobayashi et al.33) have reported that E' for 1 % results concerning DSC reported by Shimada.32) κ-carrageenan showed a pronounced decrease at 30

( 207 ) 5 J. Home Econ. Jpn. Vol. 45 No. 3 (1994)

Fig. 7. Temperature dependence of the storage modulus (E') of Cl, C-G (1:1) and G1

gels: •› Cl, A C-G (1:1), •œ Gl. Fig. 9. Temperature dependence of the dynamic

viscosity (ƒÅ') of Cl, C-G (1:1) and G1 gels:

○Cl,△C-G(1:1),●G1.

had reduced elasticity as they melted above 20•Ž,

after which the lower concentration of carrageenan

(0.45% [w/v]) began to play the main role in the whole network structure and E` for the C-G(1 :1) gel

then rapidly decreased. It was impossible to

measure E' and E" for the gelatin gels above 25•Ž.

because they were unable to keep their form be-

cause of the approaching melting temperature of

gelatin. 3. Apparent activation energy of fluidity

Fig. 8. Temperature dependence of the loss modulus Dynamic viscosity ƒÅ' for the C 1, C-G (1:1) and

(E") of Cl, C-G (1:1) and G1 gels: C Cl, G1 gels was calculated from Eq. 1 by using loss △C-G(i:i),●Gl. modulus E" (Fig. 8, above 10•Ž) and angular

frequency w as follows : to 40•Ž, which is somewhat different from our [1] results in spite of using the same K-carrageenan where co was calculated by multiplying frequency

(CS-88) in both studies. The constant or slightly v by 27. increasing E' and E" values at low temperatures The apparent activation energy of the viscous

and decreasing values with further increasing element in a gel was then evaluated by the tem-

temperature have been reported by Iida et al.34) perature dependence of the dynamic viscosity. and. Watase et al.2) for agar gels, agarose gels and The relationships between dynamic viscosity ƒÅ'

mixed agarose-gelatin gels. Iida et al.34) have and the reciprocal of absolute temperature T are

proposed, up to a certain temperature, that the shown in Fig. 9. Since the relationship between augmentation of elasticity because of the entropic 1/T and log(ƒÅ') is linear for every one of the three

nature of a gel overrides the decline of elasticity gels, it is possible to use Andrade's formula 35) as due to the disappearance of weak secondary bonds. follows: The elasticity of a gel then diminishes, since the [2] latter effect gradually overwhelmes the former. where ƒÅ' is the dynamic viscosity, AE is the activa-

It is worth noting that E' for the G1 gel drops tion energy of fluidity (kJ/mol), R is the gas con- rapidly, while it decreases gradually for the C-G stant (kj/K.•E mol), T is the absolute temperature(K),

(1:1) gel toward their melting temperature. Thus, and A is a constant. The activation energy of the gelatin molecules contained in the C-G (1:1) gel fluidity for the C 1, C-G (1:1) and G1 gels deter-

6 ( 208 ) Properties of a Mixed Carrageenan-Gelatin Gel mined from the plot in Fig. 9 was 23.6, 22.3 and considered that the side-chain groups in gelatin 29.3 kJ/mob respectively, and that for gelatin was inhibited the gelation of agarose. The hindrance higher than the value for carrageenan. The C-G of gelation after mixing carrageenan and gelatin (1:1) gel seems to reflect the properties of carra- in this study might have resulted from both water geenan, as the activation energy of fluidity for the partition when forming a network structure and C-G (1:1) gel was similar to that of the Cl gel. the interaction between OH groups in the poly- Isozaki et al.24) have reported that the activation saccharide and NH or CO groups in the gelatin. energy of Newtonian viscosity for a 1.5% (w/v) Within the concentration range used in this study, agar gel was 22.2 kJ/mol. Arakawa has pointed it is suggested that the hindrance of one gelling out that the activation energy of agar gels deter- agent against the other was very strong at a certain mined from the temperature dependence of the volume fraction, and using this volume fraction maximum relaxation time in the stress relaxation as the limit, the mixed gels showed the character- curve was 18.8 to 19.2 kJ/mol.36) As carrageenan istics of the gelling agent with the larger content. is a polysaccharide like agar, the activation energy Nevertheless, the melting temperatures of the of fluidity for the carrageenan gel in this study mixed gels were nearly equal to those of simple was fairly close to the value for an agar gel. In carrageenan gels, this being different from the addition, the value for the activation energy of a mechanical properties. Taking the C-G (1:1) carrageenan gel also approximates to that of the mixed gel as an example, this had a lower rupture hydrogen bonds, so that it can be assumed that stress while exhibiting similar behavior to the the temperature dependence of viscosity for a car- simple gelatin gel under small deformation condi- rageenan gel is mainly due to hydrogen bonding. tions, as demonstrated for E" in Fig. 5 and the Although Moritaka et al.1) have reported that the temperature dependence of E' and E" in Figs. 7 activation energy of a 30% gelatin gel was 33.4 and 8. The characteristics of mixed gels are com- kJ/mol, which is higher than that of the 4% gelatin plicated, and we need to clarify their structure for gel (Gl) used in this study, the result seems to be further elucidation. appropriate considering the 7 to 8 times concen- In addition, it is necessary to examine the effect tration of the gel and the difference in measure- of adding sub-materials to a C-G (1:1) mixed gel, ment conditions. because its melting temperature is close to 36°C, In the mixed carrageenan-gelatin system, every making it potentially suitable as a table jelly that constant had lower values compared with those of does not melt at room temperature although melts the simple component gels, and it was noted that easily in the mouth. one gelling agent inhibited the other. The melting temperatures of the mixed gels were nearly The authors express their thanks to San'ei equal to those of the equivalent simple carrageenan Chemical Co. for supplying the carrageenan sam- gels (Tables 2 and 3), and this phenomenon in- ples. This work was supported by a grant for dicates that two hydrocolloids did not form a B-category scientific research (No. 01480518) from combined network structure with each other, but the Ministry of Education, Science and Culture of formed individual networks for the most part.1)16) Japan. Accordingly, when the carrageenan gel, the gelling temperature of which is higher, begins to gelate at REFERENCES a higher temperature than the gelatin and form 1) Moritaka, H., Nishinari, K. and Watase, M.: J. the main frame of a network structure, the carra- TextureStud., 11, 257-270 (1980) geenan holds water in the mixed solution. There- 2) Watase, M. and Nishinari, K.: Nippon Shokuhin fore, the gelatin solution is unable to form a net- Kogyo Gakkaishi (J. Jpn. Soc. Food. Sci. Technol.), work structure, so that the ability for gelation of 30, 368-374 (1983) 3) Morris, V. J. : Functional Properties of Food Macro- the whole gel might be weakened. Trott et al.37) molecules, ElsevierAppl. Sci., London, 121 (1986) have reported the interaction between a polysac- 4) Watase, M. and Nishinari, K.: J. TextureStud., 12, charide and gelatin, and they concluded that OH 427-456 (1981) groups in the polysaccharide combined with NH 5) Murayama, A., Matsushita, K. and Kawabata, A.: or CO groups in the gelatin. Watase et al.2) have J. HomeEcon. Jpn., 38, 483-489 (1987)

( 209 ) 7 J. Home Econ. Jpn. Vol. 45 No. 3 (1994)

6) Murayama, A., Osako, S. and Kawabata, A.: J. Home Econ. Jpn., 34, 206-212 (1983) Home Econ. Jpn., 39, 1249-1254 (1988) 23) Murayama, A., Osako, S. and Kawabata, A.: J. 7) Hermansson, A. M.: Physical Networks, Elsevier Home Econ. Jpn., 41, 133-136 (1990) Appl. Sci., London & N.Y., 271 (1988) 24) Isozaki, H., Akabane, H. and Nakahama, N.: 8) Ledward, D.A.: Functional Properties of Food Agric. Biol. Chem., 50, 265-272 (1976) Macromolecules, Elsevier Appl. Sci., London, 171 25) Kobayashi, M., Akabane, H. and Nakahama, N.: (1986) J. Home Econ. Jpn., 32, 660-666 (1981) 9) Nishinari, K.: Hyomen, 29, 546-558 (1991) 26) Ohmura, K., Akabane, H. and Nakahama, N.: 10) Yasumatsu, K. and Fujita, E.: Eiyo to Shokuryo, J. Home Econ. Jpn., 29, 22-27 (1978) 18, 263-269 (1965) 27) Kamiichi, Y., Ohmura, K., Akabane, H. and 11) Shintani, M., Hori, Y., Yamauchi, T. and Yama- Nakahama, N.: J. Home Econ. Jpn., 31, 643-647 zaki, K.: J. Home Econ. Jpn., 26, 271-276 (1975) (1980) 12) Mitchell, J.R. : J. Texture Stud., 7, 313-339 (1976) 28) Akabane, H. and Nakahama, N.: Sci. Cookery,22, 13) Morris, V. J.: Gums and Stabilisers for the Food 173-182 (1989) Industry, 3, Elsevier Appl. Sci., Amsterdam, 87 29) Nishinari, K., Horiuchi, H., Ishida, K., Ikeda, (1985) K., Date, M. and Fukada, E.: Nippon Shyokuhin 14) Clark, A.H., Richardson, R.K., Ross-Murphy, Kogyo Gakkaishi, 27, 227-233 (1980) S.B. and Stubbs, J.M. : Macromolecules,16, 1367- 30) Hori, T.: Suri Kagaku, 122, 22-27 (1973) 1374 (1983) 31) Okano, K.: Rep. Prog. Polymer Phys. Jpn., 5, 79-82 15) Horiuchi, H. and Azuma, K.: J. Agric. Chem. Soc. (1962) Jpn., 57, 563-570 (1983) 32) Shimada, R.: J. Home Econ. Jpn. 44, 999-1005(1993) 16) Shiinoki, Y. and Yano, T.: Food Hydrocolloids, 1, 33) Kobayashi, M., Ogura F. and Nakahama, N.: J. 153-161 (1986) Home Econ. Jpn., 36, 392-398 (1985) 17) Kobayashi, M. and Nakahama, N.: J. Texture 34) Iida, F., Kobayashi, M., Akabane, H. and Naka- Stud., 17, 161-174 (1986) hama, N.: Nippon Shokuhin Kogyo Gakkaishi, 35, 18) Horiuchi, H. and Sugiyama, J.: Agric. Biol. Chem., 246-251 (1988) 51, 2171-2176 (1987) 35) Nakagawa, T.: Rheology, Misuzu Shobo, Tokyo, 19) Horiuchi, H.: Syokuryo,28, 27-48 (1989) 604 (1959) 20) Kawamura, F. and Takayanagi, S.: Sci. Cookery, 36) Arakawa, K.: Bull. Chem. Soc. Jpn., 35, 309-312 22, 147-151 (1989) (1962) 21) id: ibid., 22, 299-304 (1989) 37) Trott, G.F. and Woodside, E.E.: J. Colloid Inter- 22) Murayama, A., Fujita, M. and Kawabata, A.: J. face Sci., 36, 40-50 (1971)

カラギーナンーゼラチン混合ゲルの性状について

市川陽子, 粂野恵子 *, 赤羽ひろ * *, 中濱信子 *

(川村短期大学, * 日本女子大学, * * 関東学院女子短期大学 (現在, 日本女子大学) )

平成5年1月26日受理

κ-カラギーナン(Cl),ゼラチン(Gl)の単独ゲルにおける力学的性状の濃度依存性について,それぞれカラギーナン0.45～0.9%(w/v),ゼラチン2～4%(w/v)の範囲で検討した.さらにカラギーナン:ゼラチソ混合ゲルC-G(3:1),C-G(1:1),C-G(1:3)を調製し,破断特性,動的粘弾性,融解温度について両者の混合割合による影響を調べた.また,単独ゲル,混合ゲルの温度依存性についても検討を行った. カラギーナン,ゼラチンを混合すると,破断応力,破断エネルギー,貯蔵弾性率,損失弾性率が低下し,一方のゲル化剤が他方のゲル化剤に対し阻害的に働くことが示された.カラギーナンゲルの融解温度は濃度依存性が高いことが認められた.また,混合ゲルの融解温度は,そのゲルが含有するカラギーナンの融解温度とほぼ一致した.単独ゲル,および混合ゲルC-G(1:1)の,破断応力,破断エネルギー,貯蔵弾性率,損失弾性率は,20℃ より高温側で温度依存性がみられたが, 15℃ 以下ではエソトロピー的挙動との重畳による値の停滞または上昇が認められた.

キーワード:κ-カラギーナン,ゼラチン,混合ゲル,破断特性,動的粘弾性,みかけの活性化エネルギー.

8 ( 210 )