chitosan affects transglutaminase … for thaiscience/article/1/10016817.pdf · properties surimi...

CHITOSAN AFFECTS TRANSGLUTAMINASE-INDUCED SURIMI GELATION

SOOTTAWAT BENJAKUL'*4, WONNOP VISESSANGUA#, SUTTIRUG PHATCHRAT' and MUNEHMO TANAKA3

'Department of Food Technology Faculty of Agro-Industry

Prince of Songkla University Hat Yai, Songkhla, Thailand, 90112

2National Center for Genetic Engineering and Biotechnology National Science and Technology Development Agency

Bangkok, Thailand, 104GO

3Department of Food Science and Technology Tokyo University of Fisheries Minato-Ku, Tokyo 108, Japan

Received for Publication April 3, 2002 Accepted for Publication June 27, 2002

ABSTRACT

Effect of chitosan on barred garjfish (Hemiramphus far) surimi gel was studied in the presence of EDTA and microbial transglutaminase (MTGase) . An increase in breaking force of surimi gels added with I .O% prawn shell chitosan indicated the gel enhancing effect of chitosan on the heat-induced gelation ofjish myofibrillarproteins. However, gel-forming ability of surimi containing chitosan was inhibited in the presence of EDTA, especially at higher concentration. Therefore, the enhancing effect of chitosan was possibly mediated through the action of endogenous transglutaminase (TGase) during setting, resulting in the formation of protein-protein and protein-chitosan conjugates. In general, addition of MTGase remarkably increased both breaking force and deformation of surimi gel (P < 0.05). However, enhancing effect of MTGase was retarded in the presence of chitosan, resulting in lower magnitude of breaking force and deformation (P < 0.05). Scanning electron microscopy showed that chitosan particles were uniformly dispersed in the gel matrix. A tightly associated gel network was formed in surimi containing MTGase, whereas a large number of voids were noted in gels with EDTA. These results suggest that chitosan acted

To whom correspondence should be addressed. TEL: 66-74-286334; FAX: 66-74-212889; E-mail: bsoottaw@ratree . psu .ac . th

Journal of Food Biochemistry 27 (2003) 53-66. All Rights Reserved. OCopyright 2003 by Food & Nutrition Press, Inc., Trumbull, Connecticut. 53

54 S. BENJAKUL, W. VISESSANGUAN, S. PHATCHRAT and M. TANAKA

as a surimi gel enhancer in combination with endogenous TGase inflsh muscle, but hindered gel formution in the presence of MTGase.

INTRODUCTION

Improvement of surimi gel quality has been one of the major thrusts in surimi gel products. Gel forming ability of surimi depends on both intrinsic and extrinsic factors, including fish species (Shimizu et al. 1981), physico-chemical properties of muscle proteins (Benjakul et al. 2001), the presence of endogenous enzymes, e.g. proteinases and transglutaminase (An et al. 1996), and the conditions used in processing. Among the methods widely used, surimi gel enhancement is mainly accomplished by proper setting (Shimizu et al. 1981; Morales et al. 2001) and/or using some food grade additives. Proper setting prior to heating plays a major role in strengthening surimi gels. Formation of E-(y-glutamyl) lysine cross-linking of protein is mediated by endogenous transglutaminase (TGase) found in fish muscle (Tsukamasa et al. 1993). TGase is a calcium-dependent enzyme, which catalyzes an acyi transfer reaction between y-carboxyamide groups of glutamyl residues in proteins and primary amines (Folk and Chung 1973). When the &-amino group s f lysine acts as an acyl acceptor, &-(y-glutamy1)lysine crosslinks are formed in proteins (Folk and Finlayson 1977). However, the extent of setting response varies among fish species (Shimizu er al. 1981; Morales et al. 2001) depending on not only TGase activity (Araki and Seki 1993) but also the conformation of actomyosin (Ni et nl. 1998; Nishimoto et al. 1987). In addition to endogenous TGase, exogenous TGase, especially from microbial source or microbial transglutaminase (MTGase), has been used to increase the gel strength of surimi (Asagami et al. 1995; Seguro et al. 1995). MTGase has been applied to produce covalently cross-linked gels from various types of food proteins and considerably improved the gel strength of surimi products (Seki et al. 1990; Seguro et al. 1995).

Some food-graded additives, such as protein, carbohydrate as well as some oxidizing chemicals, have also been used to increase the gel strength (Park 1994; Yoon et al. 1997; Lee et al. 1992). Chitosan, a cationic biopolymer obtained from the N-deacetylation of chitin, a 0-( 1 -4)-linked N-acetyl-1)-glycan, improves the gel-forming ability of surimi, particularly in combination with setting and/or the addition of calcium ions (Benjakul et al. 2000). Therefore, it was presumed that endogenous TGase may play an important role in cross-linking of protein- protein and protein-chitosan conjugates, which eventually results in an increased gel strength. To provide more information, the objectives of this study were to investigate the contribution of endogenous TGase on gel strengthening effect of chitosan and to study the combined effect of chitosan and MTGase on surimi gel enhancement of barred garfish. This species normally caught in the gulf of

CHITOSAN AFFECTS SURIMI GELATION 55

Thailand has been used as the raw material for surimi production in Thailand in addition to threadfin bream, lizardfish and bigeye snapper, etc.

MATERIALS AND METHODS

Chemicals

Sodium dodecyl sulfate (SDS) and urea were obtained from Riedel-deHaen (Seelze, Germany). Glutaraldehyde, calcium chloride, 0-mercaptoethanol (p- ME) and ethylenediaminetetraacetic acid (EDTA) were purchased from Sigma (St. Louis, MO). Microbial transglutaminase (ActivaTM TG) was obtained from Ajinomoto (Ajinomoto Co., Kawasaki, Japan). Chitosan 7B from prawn shell was obtained from Katokichi Co., Ltd (Tokyo). Degree of deacetylation of 7B chitosan as determined by colloid titration method of Toei and Kohara (1976) was 65.6.

Surimi Gel Preparation

Frozen surimi from barred gatfsh (Grade A) was purchased from Man-A Frozen Foods Co. (Songkhla, Thailand). Frozen surimi was tempered for 30 min in running water (292). The surimi was then cut into small pieces with an approximate thickness of 1 cm. The surimi was placed in a mixer (National Model MK-K77, Tokyo). Chitosan 7B (1%) was added into surimi paste with and without EDTA (5 and 10 mol/kg) or MTGase (0.1, 0.2 and 0.5%). EDTA was added as an inhibitor of TGase. The moisture was adjusted to 80% and 2.5% salt was added. To obtain a homogenous paste, the mixture was chopped for 5 min at 4C. The temperature of surimi sol was kept below 1OC. The surimi sol was stuffed into the polyvinylidine casing (2.5 cm diameter) and both ends were sealed tightly. The gels were prepared by setting sol at 25C for 3 h in a temperature-controlled water bath (Memmert, Schwabach, Germany), followed by heating at 90C for 20 min in a water bath. The gels were then cooled in iced water and stored at 4C for 24 h before analysis.

Texture Analysis

Texture analysis of surimi gel was performed using a texture analyzer Model TA-XT2 (Stable Micro Systems, Surrey, England). Gels were equilibrat- ed and tested at room temperature. Five cylinder-shaped samples of 2.5 cm in length were prepared. The breaking force (gel strength) and deformation (elasticityldeformability) were measured using the texture analyzer equipped with a cylindrical plunger (5 mm diameter; 60 d m i n deformation rate).

56 S. BENJAKUL, W. VISESSANGUAN, S. PHATCHRAT and 'M. TANAKA

SDS-Polyacrylamide Gel Electrophoresis (SDS-PAGE)

SDS-PAGE was carried out according to the method of Laemmli (1970) using 4% stacking gel and 10% running gel. Surimi sol or gel (3 g) was homogenized with 27 mL of 5% SDS solution (85C). The homogenate was incubated at 85C for 1 h to solubilize total proteins. The supernatant was collected after centrifuging at 3,500 xg for 5 min at room temperature. Protein (15 pg) was applied on the gel. After separation, proteins were fixed and stained with Coomassie Blue R-250 and destained in 25% ethanol and 10% acetic acid successfully. High molecular weight standards (Sigma, St. Louis, MO) were used as reference to identify the mass of protein bands.

Determination of Protein Content

The protein content was measured according to the methods of Lowry et al. (1951) using bovine serum albumin as the standard.

Scanning Electron Microscopy (SEW

Gel samples were fixed with 2.5% glutaraldehyde: in 0.1 M sodium phosphate (pH 7.2) for 1-2 h at room temperature (28-3OC). Fixed specimen was dehydrated in ethanol solution with the concentration ranging from 50 to 100% in successive manner. The specimen was coated with gold layer and observed with a JEOL Scanning Electron Microscope Model JSM5800LV (Tokyo).

Statistical Analysis

run by Duncan's multiple range test (Steel and Torrie 1980). Analysis of variance (ANOVA) was performed and mean comparisons were

RESULTS AND DISCUSSION

Effect of Chitosan in Combination with TGase Inhibitor on Surimi Gel Properties

Surimi gel containing 1 % chitosan 7B alone exhibited the highest magnitude of breaking force (P<0.05), compared to the control and those with EDTA (Fig. 1). An increase in breaking force (approximately 24%) was observed with the addition of chitosan. The results were similar to those previously reported by Kataoka et al. (1998) and Benjakul et al. (2000). Gel strength of walleye pollock surimi increased about two-fold by adding 1.5 % chitosan in combination with setting at 20C (Kataoka et al. 1998). Recently, Benjakul er al. (2000)


reported an increase in gel strength of surimi from barred garfish containing 1 % 7B chitosan and calcium chloride. It was postulated that amino groups of chitosan molecules partially cross-linked with myofibrils and also worked as a filler in the gel matrix (Benjakul e? al. 2000). In conjunction with setting and the addition of calcium ions, endogenous TGase may play an important role in cross-linking of protein-protein and protein-chitosan conjugates by using amino group of chitosan as the acyl acceptor.

The addition of EDTA lowered the gel formation of surimi, resulting in a decrease in breaking force and deformation (Fig. 1). Compared to that of control, breaking force of surimi gel with EDTA alone decreased about 5 % and 38% with the increasing concentration of EDTA from 5 to 10 mmol/kg, respectively. EDTA added at high concentration possibly affected surimi gelation by inhibiting endogenous TGase activity. TGase has been known to induce the formation of isopeptide bonds between fish myosin molecules, which is considered to be related to the gel strength of minced fish (Jiang 2000). The addition of 5 mmol EDTA/kg surimi completely suppressed the gel formation and no &-(y-glutamy1)lysine isopeptide was observed (Kumazawa e? al. 1995). Transglutaminase from fish muscle generally requires calcium ion for its full activation and it plays an important role in setting of surimi gel (Kimura ef al. 1991; Kishi et al. 1991; Seki e? al. 1998). Calcium is generally present in the fish muscle at varying amounts, depending on species. Saeki e? al. (1988) reported that pollack surimi contained 0.6 mmol of calcium ion/kg. In the presence of EDTA, calcium ions were chelated and unavailable for transglutaminase activation, leading to a decreased TGase-induced cross-linking with a concomitant decrease in breaking force and deformation.’fhe result indicated the role of endogenous transglutaminase in cross-linking of myofibrils during setting of surimi from barred garfish.

The addition of EDTA also considerably reduced the enhancing effect of chitosan in surimi gel. Marked decreases in breaking force and deformation were observed in the gel with both chitosan and EDTA (Fig. 1). TGase catalyzes a reaction, which incorporates a variety of primary amines covalently into reactive glutamine residues on the surface of substrate proteins as well as the cross-linking of polypeptides through the formation of isopeptides between lysine and glutamine residues (Folk 1970). Amino group of chitosan can be an acyl acceptor in the acyl transfer reaction from y-carboxylamide group of peptide-bound glutamyl residue. Benjakul e? al. (2000) found that barred garfish surimi gel with chitosan and calcium chloride had a much higher breaking force. Full activation of transglutaminase by sufficient calcium ion induced the cross- linking between myofibrils and the formation of myofibril-chitosan conjugates.


1200 -

lo00 -

? 800

5 f 600 m

400

200

0 mntrd l%hItmmn 5 m M EDTA I0 m M EDTA Wehitosm + l%hitoun + 10

5 m M EDTA m M EDTA

14 .

12 -

- 10 -

3 8 -

f 6 6 -

A -

2 -

0 - rontrol Io/rhitoim 5 m M EDTA 10 mM EDTA I*&hitoun + 5 l%hiIoun + Ill

mM EDTA m M EDTA

FIG. 1. EFFECT OF EDTA AT VARIOUS CONCENTRATIONS ON BREAKING FORCE AND DEFORMATION OF BARRED GARFISH SURIMI GELS CONTAINING CHITOSAN

Bars represent standard deviation from 5 determinations.


Setting extensively reduced the band intensity of myosin heavy chain (MHC) of surimi gels, compared with surimi paste (Fig. 2). Generally, MHC band decreased during setting via cross-linking of myosin heavy chain, particularly when setting was prolonged (Numakura et al. 1985; Nowsad et al. 1993). Polymerized myosins could not enter the SDS-PAGE gel, leading to the reduction of the band intensity. With the addition of EDTA, transglutaminase inhibitor, greater MHC band intensity was observed. MHC band intensity was found to be great with the increasing concentrations of EDTA added. This reconfirms that endogenous TGase played an essential role in setting of barred garfish surimi.A larger decrease in MHC band intensity was observed with the sample added with chitosan alone. Therefore, it was postulated that more protein crosslinks were possibly formed in the presence of chitosan, especially in the form of protein-chitosan conjugate. However, such cross-linking reaction was suppressed in the presence of EDTA. The results suggest that endogenous TGase mainly involved in cross-linking of myofibrils, which could work synergistically with chitosan.

- MHC

- actin

1 2 3 4 5 6 7

FIG. 2. SDS-PAGE PATTERN OF BARRED GARFISH SURIMI GEL CONTAINING CHITOSAN AND EDTA AT VARIOUS CONCENTRATIONS

(1) surimi sol; (2) control surimi gel; (3)-(4) surimi gel with 5 and 10 mmol EDTA/kg; (5)-(7) surimi gel with 1 W chitosan and 0, 5, and 10 mmol EDTAIkg, respectively.

Effect of Chitosan in Combination with MTGase on Surimi Gel Properties

Microbial transglutaminase (MTGase) effectively increased the breaking force of surimi gel (Fig. 3). The breaking force of surimi gel increased by 45- 54% with the addition of 0.1 % MTGase, and no further increase was observed


beyond this level. A significant decrease in deformation was observed at 0.5% MTGase (P<0.05). This is in agreement with the results of Seguro et al. (1995) who reported that the decrease in deformation may have resulted from the excess formation of e(y-glutamy1)lysine isopeptide with MTGase.

No synergistic effect of chitosan and MTGase on gel enhancement was observed (Fig. 3). Conversely, gels supplemented with both chitosan and MTGase rendered lower breaking force and deformation than those with MTGase alone but higher than control and those with chitosan alone (P<0.05). This suggests that the addition of chitosan lowered the gel strengthening effect of MTGase on surimi. It was postulated that the amino groups of chitosan may not act as a good acyl acceptor for MTGase, compared to those of myofibrils. As a consequence, chitosan particles probably behaved as the barrier for the cross-linking between myofibrils. Nevertheless, surimi supplemented with both chitosan and MTGase resulted in the significant increase in breaking force of surimi, compared to that with chitosan alone. In general, MTGase produced protein crosslinks much faster and more extensively than carp endogenous TGase (Nakahara et al. 1999). In addition to polymerization of myosin, MTGase produced highly polymerized forms of myofibrillar proteins such as heteropoly- mers between connectin and actin. MTGase also cross-linked the myofibrils at different sites from carp endogenous TGase. The addition of a higher amount of MTGase to surimi resulted in a significant decrease in deformation (P < 0.05).

The surimi supplemented with MTGase showed a marked decrease in the MHC band intensity with increasing concentrations (Fig. 4). The MHC band completely disappeared with the addition of MTGase at 0.5 % . However, no changes in actin were noted. Nakahara et al. (1999) reported that both MTGase and carp endogenous TGase could not cross-link actin molecules. It was shown that MTGase preferentially cross-linked connectin, followed by MHC, troponin T, and actin, respectively. Although the differences in breaking force were noted in the presence of both chitosan and MTGase (Fig. 3), no marked differences in the electrophoretic patterns were observed in comparison with gels with MTGase or chitosan alone. It was postulated that chitosan itself was less reactive to MTGase than endogenous TGase. As a result, protein-chitosan conjugate was formed at a smaller extent. Less formation of protein-chitosan conjugate in the presence of MTGase may lead to the formation of noncontinuous matrix or less cross-linked matrix and thus smaller increase in breaking force and deformation was obtained by the addition of both chitosan and MTGase.


1200 1400 0 1000

; 800

m Ba

e P

400

200

0

16

FIG. 3. EFFECT OF MTGase AT VARIOUS CONCENTRATIONS ON BREAKING FORCE AND DEFORMATION OF BARRED GARFISH CONTAINING CHITOSAN

Bars represent standard deviation from 5 determinations.

62 S. BENJAKUL. W. VISESSANGUAN, S. PHATCHRAT and M. TANAKA

- MHC

- actin

1 2 3 4 5 6 7 8 9

FIG. 4. SDS-PAGE PATTERN OF BARRED GARFISH GEL CONTAINING CHITOSAN AND MTGase AT VARIOUS CONCENTRATIONS

(1) suruni sol; (2) control surimi gel; (3)-(5) surimi gels with MTGase at 0.1, 0.2, and 0 . 5 % . respectively; (6)-(9) surimi gels with 1% chitosan and MTGase at 0, 0.1, 0.2,

and 0.5%. respectively.

Effect of EDTA and MTGase on Microstructure of Surimi Gels with Chitosan

Fine microstructure was observed in the surimi gel with chitosan (Fig. 5). It was noted that chitosan particles dispersed uniformly and tightly associated in the gel network. However, more fibrous and coarser structure was noted in the gels with EDTA, which mainly suppressed cross-linking reaction induced by endogenous TGase during setting. Less cohesive and loose matrix of both protein-protein filaments and protein-chitosan particles was formed. Compared to gel with EDTA, gel with MTGase exhibited more cohesive structure between protein-protein filaments. Since both endogenous TGase and MTGase directly affected the gel quality of surimi by inducing the polymerization of myofibrils, chitosan possibly affected the rate and extent of polymerization differently between both enzymes. MTGase appeared to show less reactivity to chitosan than endogenous TGase. Therefore chitosan probably functions as a gel hindrance in MTGase supplemented gel, where rapid polymerization of myofibrillar proteins occurred. Conversely, it probably acted as surimi gel enhancer in endogenous TGase containing gel, where the polymerization was formed at a slower rate.

CHITOSAN AFFECTS SURIMI GELATION

A)

63

FIG. 5. SCANNING ELECTRON MICROGRAPHS OF BARRED GARFISH SURIMI GELS IN THE PRESENCE WITH CHITOSAN A M N E (A), CHITOSAN AND 10 mmol

EDTAlkg (B), AND CHITOSAN AND 0.1 % MTGase (C)

64 S. BENJAKUL, W. VISESSANGUAN, S . PHATCHRAT and N. TANAKA

CONCLUSION

Gel strengthening effect of chitosan was mediated through the reaction of endogenous TGase. However, no synergistic effect on gel strengthening was observed when chitosan was added in combination with MTGase. The results suggest that two types of TGase exhibited different specificity to chitosan, particularly in terms of the formation of chitosan-protein conjugate.

ACKNOWLEDGMENT

Authors would like to thank the Japanese Society for. the Promotion of Science (JSPS) for the support.

REFERENCES

AN, H., PERTERS, M.Y. and SEYMOUR, T.A. 1996. Roles of endogenous enzymes in surimi gelation. Trends Food Sci. Technol. 7, 321-327.

ARAKI, H. and SEKI, N. 1993. Comparison of reactivity of transglutaminase to various fish actomyosin. Nippon Suisan Gakkaishi 59, 711-716.

ASAGAMI, T., OGIWARA, M., WAKAMEDA, A. and NOGUCHI, S.F. 1995. Effect of microbial transglutaminase on the quality of frozen surimi made from various kinds of fish species. Fish. Sci. 61, 267-272.

BENJAKUL, S., VISESSANGUAN, W., ISHIZAKI, S. and TANAKA, M. 2001. Differences in gelation characteristics of natural actomyosin from two species of bigeye snapper, Pnacanthus tayenus and Pnacanthus macrucanthus. J. Food Sci. 66, 131 1-1318.

BENJAKUL, S., VISESSANGUAN, W., TANAKA, M., ISHIZAKI, S., SUTHIDHUM, R.A. and SUNGPECH, 0. 2000. Effect of chitin and chitosan on gelling properties of surimi from barred garfish (Hemiramphus far). J. Sci. Food Agric. 81, 102-108.

FOLK, J.E. 1970. Transglutaminase. Methods Enzymol. 17, 889-894. FOLK, J.E. and CHUNG, S.I. 1973. Molecular and catalytic properties of

transglutaminase. Adv . Enzymol . 38, 109- I9 1. FOLK, J.E. and FINLAYSON, J.S. 1977. The 8-(y-glutamy1)lysine crosslink

and the catalytic role of transglutaminase. Adv. Protein Chem. 31, 1-133. JIANG, S.T. 2000. Enzymes and their effects on seafood texture. In Seafood

Enzymes: Utilization and Influence on Posthutvest Seafood Quulig, (N. F. Haard and B.K. Simpson, eds.) pp. 41 1-450, Marcel Dekker, New York.

KATAOKA, J . , ISHISAKI, S. and TANAKA, M. 1998. Effects of chitosan on gelling properties of low quality surimi. J . Muscle Foods 9, 209-220.

CHITOSAN AFFECTS SUFUMI GELATION 65

KIMURA, I., SUGIMOTO, M., TOYODA, K., SEKI, N., ARAI, K. and FUJITA, T. 1991. A study on the cross-linking reaction of myosin in kamaboko “Suwari” gels. Nippon Suisan Gakkaishi 57, 1389-1396.

KISHI, H., NOZAWA, H. and SEN, N. 1991. Reactivity ofmuscle transglutaminase on carp myofibrils and myosin B. Nippon Suisan Gakkaishi 57,

KUMAZAWA, Y., NUMAZAWA, T., SEGURO, K. and MOTOKI, M. 1995. Suppression of surimi gel setting by transglutaminase inhibitors. J. Food Sci. 60, 715-717.

LAEMMLI, U.K. 1970. Cleavage of structural proteins during the assembly of head of bacteriophage T4. Nature 227, 680-685.

LEE, H.G., LEE, C.M., CHUNG, K.H. and LAVERY, S.A. 1992. Sodium ascorbate affects surimi gel-forming properties. J. Food Sci. 57, 1343- 1347.

LOWRY, O.H., ROSEBROUGH, N.J., FARR, A.L. and RANDALL, R.J. 1951. Protein measurement with Folin phenol reagent. J. Biol. Chem. 193,

MORALES, O.G., RAMIREZ, J.A., VIVANCO, D.I. and VAZQUEZ, M. 2001. Surimi of fish species from the gulf of Mexico: evaluation of the setting phenomenon. Food Chem. 75, 43-48.

NAKAHARA, C., NOZAWA, H. and SEKI, N. 1999. A comparison of cross- linking of fish myofibrillar proteins by endogenous and microbial transglutaminase. Fish. Sci. 65, 138-144.

NI, S . , NOZAWA, H. and SEKI, N. 1998. Effect of microbial transglutaminase on thermal gelation of carp actomyosin sol. Fish. Sci. 64, 434-438.

NISHIMOTO, S., HASHIMOTO, A., SEKI, N., KIMURA, I., TOYODA, K., FUJITA, T. and ARAI, K. 1987. Influencing factors on changes in myosin heavy chain and jelly strength of salted meat paste from Alaska Pollock during setting. Nippon Suisan Gakkaishi 53, 201 1-2020.

NOWSAD, A.A.K.M., KANOH, S. and NIWA, E. 1993. Electrophoretic behavior of cross-linked myosin heavy chain in suwari gel. Nippon Suisan Gakkaishi 59, 667-671.

NUMAKURA, T.M., SEKI, N., KIMURA, I., TOYODA, K., FUJITA, T., TAKAMA, K. and ARAI, K. 1985. Cross-linking reaction of myosin in the fish paste during setting (Suwari). Nippon Suisan Gakkaishi 51,

PARK, J.W. 1994. Functional protein additives in surimi gel. J. Food Sci. 59,

SAEKI, H., OZAKI, H., NONAKA, M., SEKI, N. and ARAI, K. 1988. Effect of CaC1, in frozen surimi of Alaska pollack on cross-linking of myosin heavy chain in salted paste from the same material. Nippon Suisan Gakkaishi 54, 259-264.

1203- 1 2 10.

256-275.

1559- 1565.

525-527.


SEGURO, K., KUMAZAWA, Y., OHTSUKA, T., TOIGUCHI, S. and MOTOKI, M. 1995. Microbial transglutaminase and &-(y-glutamy1)lysine crosslink effects on elastic properties of kamaboko gels. J. Food Sci. 60,

SEKI, N., NOZAWA, H. and NI, S. 1998. Effect of transglutaminase on the gelation of heat-denatured surimi. Fish. Sci. 64, 959-963.

SEKI, N., UNO, H., LEE, N.H., KIMURA, I., TOYODA, K., FUJITA, T. and ARAI, K. 1990. Transglutaminase activity in Alaska pollack muscle and surimi, and its reaction with myosin B. Nippon Suisan Gakkaishi 56,

SHIMIZU, Y., MACHIDA, R. and TAKENAMI, S. 1981. Species variation in the gel-forming characteristics of fish meat paste. Hull. Jap. SOC. Sci. Fish. 47, 95-104.

STEEL, R.G.D. and TORRIE, J.H. 1980. Principles and Procedures of Statistics; A Biometrical Approach, 2"d Ed., McGraw-Hill, New York.

TOEI, K. and KOHARA, T.A. 1976. A conductometric method for colloid titrations. Anal. Chim. Acta 83, 59-65.

TSUKAMASA, Y., SATO, K., SHIMIZU, Y., IMAI, I., SUGIMOTO, M., MINEGISHI, Y. and KAWABATA, M. 1993. &-(y-glutamy1)lysine crosslink formation in sardine myofibril sol during setting at 25 "C . J . Food Sci. 58, 785-787.

YOON, Y.B., KIM, B.Y. and PARK, J.W. 1997. Linear programming in blending various components of surimi seafood. J. Food Sci. 62,564-567.

305-3 1 1.

125-132.

chitosan affects transglutaminase … for thaiscience/article/1/10016817.pdf · properties surimi...

Documents