The kinetics of gelation of an ungelled carrageenan solution exposed to a gel-inducing ionic solution was studied using a turbidity technique. Alkali metal ions were allowed to diffuse through a dialysis membrane into the solution of biopolymer. Optical transmission was measured as a function of dis
Turbidity investigation of the sol–gel transition in carrageenan gels under physiologic conditions
✍ Scribed by Yuanye Chen; Zhibing Hu; John C. Lang
- Publisher
- John Wiley and Sons
- Year
- 1998
- Tongue
- English
- Weight
- 219 KB
- Volume
- 68
- Category
- Article
- ISSN
- 0021-8995
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✦ Synopsis
A spectrophotometer was used to measure the turbidity of a carrageenan gel as a function of temperature. The optical transmission of the gels was found to decrease as the gels undergo the sol-gel phase transition. The differential of transmission (I) with respect to temperature ( T ), dI/dT, exhibits peaks for both the cooling and the heating runs with the peak positions corresponding to temperatures of gelation and melting, respectively. The full-width at half-height of the dI/dT peak obtained from the heating curve is about 2.5 times broader than that from the cooling curve. This indicates that the melting of gels may involve multiple relaxation mechanisms. The area of the hysteresis loop covered by the cooling and the heating curves increases with a decrease in the scanning rate. The thermal cycling has little impact on the solgel transition in the gels. The experiments show that turbidity is a powerful tool for studying the sol-gel transition in carrageenan gels.
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