NMR study on the network structure of a mixed gel of kappa and iota carrageenans.
The temperature dependencies of the (1)H T2 and diffusion coefficient (D) of a mixed solution of kappa-carrageenan and iota-carrageenan were measured by NMR. Rheological and NMR measurements suggested an exponential formation of rigid aggregates of kappa-carrageenan and a gradual formation of fine aggregates of iota-carrageenan during two step increases of G'. The results also suggested that longer carrageenan chains are preferentially involved in aggregation, thus resulting in a decrease in the average Mw of solute carrageenans. The results of diffusion measurements for poly(ethylene oxide) (PEO) suggested that kappa-carrageenan formed thick aggregates that decreased hindrance to PEO diffusion by decreasing the solute kappa-carrageenan concentration in the voids of the aggregated chains, and that iota-carrageenan formed fine aggregates that decreased the solute iota-carrageenan concentration less. DPEO in a mixed solution of kappa-carrageenan and iota-carrageenan suggested two possibilities for the microscopic network structure: an interpenetrating network structure, or micro-phase separation.
Department of Food Science and Technology, Tokyo University of Marine Science and Technology, 4-5-7 Konan, Minato-ku, Tokyo 108-8477, Japan.
Bingjie
B
Hu
Department of Food Science and Technology, Tokyo University of Marine Science and Technology, 4-5-7 Konan, Minato-ku, Tokyo 108-8477, Japan.
Lei
L
Du
Department of Food Science and Technology, Tokyo University of Marine Science and Technology, 4-5-7 Konan, Minato-ku, Tokyo 108-8477, Japan. Electronic address: matsukaw@kaiyodai.ac.jp.
Shingo
S
Matsukawa
D002351:Carrageenan / Q000737:chemistry*; D004058:Diffusion; D005782:Gels; D009682:Magnetic Resonance Spectroscopy; D011092:Polyethylene Glycols / Q000737:chemistry; D013696:Temperature
D005782:Gels; D011092:Polyethylene Glycols; D002351:Carrageenan
Diffusion coefficient; Gelation; Gradient NMR; Microscopic structure; Mixture of carrageenans