Effect Of Gamma Irradiation On Sodium Alginate And Carrageenan Powder.pdf

Agricultural and Biological Chemistry

ISSN: 0002-1369 (Print) (Online) Journal homepage: https://www.tandfonline.com/loi/tbbb19

Effect of Gamma-irradiation on Sodium Alginate and Carrageenan Powder Tamikazu Kume & Masaaki Takehisa To cite this article: Tamikazu Kume & Masaaki Takehisa (1983) Effect of Gamma-irradiation on Sodium Alginate and Carrageenan Powder, Agricultural and Biological Chemistry, 47:4, 889-890, DOI: 10.1080/00021369.1983.10865740 To link to this article: https://doi.org/10.1080/00021369.1983.10865740

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Agric. Bioi. Chem., 47 (4),889",890, 1983

889

Note

Effect of Gamma~i~radiation on Sodium Alginate and Carrageenan Powder Tamikazu

KUME

and Masaaki T AKEHISA

Takasaki Radiation Chemistry Research Establishment, Japan Atomic Energy Research Institute, Takasaki, Gunma 370-12, Japan

Received October 22, 1982·

Sodium alginate and carrageenan derived from brown and red marine algae,respectively, have recently received attention as emulsifying, thickening and stabilizing agents, as well as a dietary food. It has been reported that the feeding of sodium alginate is effective in reducing the bone uptake pf radioactive strontium1 ) and in reducing the strontium contamination of cow's milk. 2 ) These carbohydrates are also used as a clarifying agent for wine and beer. Hartmann et al. 3 ) have reported that irradiation is not appropriate for sterilization of the contaminated microorganisms in sodium alginate because of the decrease in viscosity. It is, however, necessary to investigate the changes in quality of the carbohydrate as an absorbent or coagulant due to irradiation. This communication reports the irradiation effect on the viscosity, surface charge and effectiveness as a coagulant of sodium alginate and carrageenan. The carbohydrate powders were irradiated at room temperature in air by y-rays from a 60 kCi cobalt-60 slab source. The viscosity of a 1% solution was measured with a Brookfield B8L-HM viscometer at 35°C. The negative surface charge of the carbohydrates was measured by colloid titration. 4 ) Five ml of 1% carbohydrate solutions

TABLE

Sodium alginate

Moisture

Aa

13.2

Ba

13:0

Cb

20.2

(/~)

I.

were mixed with 7 ml of N/200 glycol chitosa~ solution and the excess of the added glycol chitosan was titrated with N/400 potassium polyvinylsulfonate solution, using toluidine blue as an indicator. The effectiveness as a precipitating agent for protein turbidity in sake (Japanese rice wine) was determined as follows; carbohydrate (0.01 g) dissolved in 5 ml of sake was added to 100 ml of sake ·containing 0.04% persimmon tannin, and the transmittance at 430 nm of the supernatant was measured after standing at room temperature for 30 hr. Table I shows the irradiation effect on pH, viscosity and relative surface charge for three kinds of sodium alginate which are technical grades for food. The pH and relative surface charge were hardly changed while the viscosity decreased markedly by the irradiation of 5.0 Mrad for sterilization. From these results, it is considered that radiation sterilized sodium alginate is not applicable for use as a thickening or gelling agent but can be used as an absorbent or coagulant. For detail study, reagent grade sodium alginate (Kishida Chemical Co. Ltd.) and carrageenan (A-type, sulfuric acid group: ca. 29%, Tokyo Chemical Industry Co. Ltd.) were used. Table II shows the changes in pH and relative surface charge of the carbohydrates when irradiated with a high dose up to 50 Mrad. The pH increased in sodium alginate, but decreased in carrageenan with an increase in dose. The relative surface charge was stable with irradiation and only decreased by about 10% in both carbohydrates at 50 Mrad.· On the other hand, the viscosity was decreased markedly by irradiation in both carbohydrates. As shown in Fig. 1, the decrease in viscosity of carrageenan was larger than that· of sodium alginate. These results indicate that the change in effectiveness as absorbents or coagulants would be small, even at 50 Mrad. For an application of irradiated carbohydrates, their effectiveness as a precipitating agent for protein turbidity in sake was examined. The turbidity in sake caused by heat denaturation of proteins 5 ) is removed by a precipitation method with persimmon tannin and high molecular materials such as sodium alginate, carrageenan,

EFFECT OF y-IRRADIATION ON SODIUM ALIGINATE

Dose

ViscosityC (cp)

Relative charge (%)

pHd

Unirradiated 5.0 Mrad Unirradiated 5.0 Mrad U nirradiated 5.0 Mrad

214 4.3 379 4.4 159 3.6

100 101 100 102 100 101

6.68 6.72 6.68 6.69 6.70 6.82

Made in Japan. Made in China. C Viscosity of 1% solution was measured with a Brookfield viscometer at 35°C. d pH of 0.1 % solution was measured.

a

b

T. KUME and M. TAKEHISA

890

TABLE II. CHANGES IN pH AND RELATIVE SURFACE 'CHARGE OF SODIUM ALGINATE AND CARRAGEENAN BY y-IRRADIATION Sodium alignate Dose (Mrad)

Relative

U nirradiated 0.1 0.5 1.0 2.5 5.0 10.0 50.0

*

Carrageenan

pH* charge (%)

Relative pH* charge (%)

7.52 7.47 7.59 7.67 7.72 7.72 7.79 7.74

8.83 8.80 8.53 7.80 7.68 7.39 6.58 3.42

100 100 101 97 98 100 100 89

100 101 100 103 102 99 96 87

pH of 1% solution was measured. 10

TABLE III. EFFECTIVENESS AS A COAGULANT OF IRRADIATED CARBOHYDRATES FOR PROTEIN TURBIDITY IN Sake (RICE WINE)

3

0u

Dose (Mrad) U nirradiated 10 50

Transmittance (%) at 430nm Sodium alginate

Carrageenan

77.6 90.6 91.0

77.6 88.4

rageenan, while it was not clarified completely after 30 hr with unirradiated carbohydrates. The transmittance at 430 nm of the supernatants after standing for 30 hr are shown in Table III. This result indicates that irradiation accelerates the effectiveness of the carbohydrates as coagulants and it was especially effective in sodium alginate. From these results, it is concluded that the radiation sterilization method can be appropriate for carbohydrates as absorbents or coagulants. Furthermore, high dose irradiation impr0v.es the quality of carbohytlrates as coagulants.

Acknowledgments. The authors wish to thank Kimitsu Chemical Industry Co. Ltd. for providing the sodium alginates, and Professor H. Iizuka of the Science University of Tokyo and Dr. H. Ito and Dr. H. Watanabe of their Institute for suggestions and discussions.

REFERENCES 2

3

Dose (M rad)

FIG. 1. Changes in Viscosity of Sodium Alginate and Carrageenan by y- Irradiation. Viscosity of 1% solution was measured at 35°C. Symbols: 0, sodium alginate; 6., carrageenan.

etc. However, this procedure is not particularly effective and requires much time in some sake. When the clarification effect was observed with the naked eye,6) the turbidity of sake was clarified after 8 hr with irradiated sodium alginate and after 30 hr with irradiated car-

1) D. Waldron-Edward, T. M. Paul and S. C. Skoryna, Nature, 205, 1117 (1965). 2) R. A. Wentworth, C. L. Comer and J. J. Anderson, NYO-2147-13, 1968, p. 23. 3) A. W. Hartman, R. U. Nesbitt, Jr., F. M. Smith and N. O. Nuessle, J. Pharm. Sci., 64, 802 (1975). 4) R. Senju, "Colloid Titration Method," Nankodo, Tokyo, 1969. 5) S. Mikami and Y. Nunokawa, Hakkokogaku Kaishi, 56, 194 (1978). 6) T. Kume, K. Vagi, H. Ueno, S. Aoki and T. Sato, JAERI-M 9256 (1981).