碩士 / 國立臺灣大學 / 食品科技研究所 / 86 / The purpose of this study was to elucidate the correlations between the ultr
asonic degradation characteristics and the molecular properties of red algalpo
lysaccharides. Agarose, k- and i-carrageenans were dissolved in water (0.5g/dl
), and being ultrasonicated at 50oC for 0 ~ 12 h. The intrinsic viscosityweigh
t-average molecular weight and its distribution as well as diffusion character
istics of ultrasonicated samples were examined. The results of intrinsicviscos
ity measurements indicate that the viscosity decreased from 3.37 to 2.75dl/g f
or agarose, from 6.47 to 2.98 dl/g for k-c arrageenan, and from 14.58 to 6.48
dl/g for i-carrageenan with increasing ultrasonic period from 0 to 12 h. The
short-term degradation of these polysaccharides appears to follow a first-orde
r reaction with an initial degradation rate (ko) of k- carrageenan > i-carrage
enan > agarose. Besides, the change in molecular weight distribution is insign
ificant for ultrasonicated agarose, but notable for the two carrageenans. Furt
hermore, the proportion of larger molecular weight fraction in carrageenan sam
ples decreased as ultrasonic period increased, implying the feasibility of the
large molecules by degradation rather than the small ones. The dynamic light
scattering measurements further show that agarose has a greater translational
diffusion coefficient than the carrageenans. This property may also play an im
portant role in governing the degradation rate of red algal polysaccharides by
ultrasonication.
| Identifer | oai:union.ndltd.org:TW/086NTU00252017 |
| Date | January 1998 |
| Creators | Chen, Chun-hsien, 陳俊賢 |
| Contributors | Cheng-yi Lii, An-I Yeh, 呂政義, 葉安義, --- |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 80 |
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