Kappa-carrageenan gels between

The biosensor [1] was obtained by coupling a transducer (an ampero-metric electrode for hydrogen peroxide) with the superoxide dismutase enzyme immobilized in kappa-carrageenan gel. Sandwich the gel containing the enzyme between a cellulose acetate membrane and a dialysis membrane. Secure the whole assembly to the electrode with an O-ring (Fig. 12.1). 

Campanella et al. [1] Superoxide radical polyphenols Sulfite Ascorbic acid Wine Superoxide dismutase (SOD), or tyrosinase, or sulfite oxidase, or ascorbate axidase/in a gel-like kappa-carrageenan membrane sandwiched between a cellulose acetate membrane and a dialysis membrane Amperometric Pt electrode for hydrogen peroxide (for superaxide determination)/ +650 mV vs. Ag/AgCl/ Amperometric oxygen electrode (for the rest)/-650 mV vs. Ag/AgCl... 

Rochas and Rinaudo [569] constructed a phase diagram, where the logarithm of the total ionic concentration is plotted vs the reciprocal transition temperature (see Fig. 221). It characterizes the conformation and gelation of kappa carrageenan in KCl solutions. In domain I (relatively low concentration and high temperatureX only polymer coils are present in domain II (relatively low concentration and low temperature), the kappa carrageenan molecules are in the ordered, helical conformation, whereas in domain in (relatively high concentration and low temperature the system is in the (helical) gel state the boundary between domains II and III is not sharply known and for that reason is indicated by a wavy line. 

Below a critical concentration (C = 7 x 10 mol/1 and T = 20 °Q, no gel formation is possible the line corresponds to the transition between coils and helices above C gel formation is possible and a difference between a heating and a cooling process is perceptible (hysteresis). The phase diagrams of iota and kappa carrageenan differ, as shown in Fig. 222. It turns out that gels are more... 

Damasio, M.H., Fiszman, S.M., Costell, E. Duran, L. (1990). Influence of composition on the resistance to compression of kappa carrageenan-locust bean gum-guar gum mixed gels relationship between instrumental and sensorial measurements. Food Hydrocolloids, Vol.3, No. 6, pp. 457-464, ISSN 0268-005X. 

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