Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/51246
標題: 桑葉多醣基礎流變特性之研究
Rheological Characteristics of the Polysaccharides Extracted from Mulberry (Morus alba L.)Leaves
作者: Tsai, Jui-Chu
蔡瑞珠
關鍵字: 流變;Rheological;多醣;桑葉;Polysaccharides;Mulberry Leaves
出版社: 食品暨應用生物科技學系
摘要: 
本研究以碳酸氫鈉溶液萃取桑葉多醣,續以乙醇沈澱,經真空乾燥即得桑葉多醣。利用毛細黏度管及動態流變儀,並添加單價鹽類或雙價鹽類於桑葉多醣溶液,探討桑葉多醣溶液及添加鹽類對桑葉多醣溶液之流變性質的影響。結果顯示,桑葉多醣分子量約為690,000;Mark - Houwink指數為1.24,Mark – Houwink常數(k×106)為50.1。桑葉多醣溶液之比黏度隨著鹽濃度之增加而降低,添加單價鹽類之桑葉多醣分子其鹽耐受性約為12.34-13.42 ml M0.5 /g,相對鏈強度參數則約為0.004;添加二價鹽類,其相對鏈強度參數約介於0.003-0.0004,較一般多醣膠質為低,顯示其分子鏈鍵結較強。桑葉多醣溶液之比黏度及固有黏度隨溫度之升高而降低,且比黏度與多醣濃度成冪次函數關係。線圈纏繞值約為5.55至6.68,稀釋區之指數介於0.94至1.03,濃縮區則介於2.09至2.60及2.85至3.06。於穩剪切測試之結果,不同濃度之桑葉多醣溶液在測試範圍內皆呈剪切致稀性,其於冪次模式中之黏稠指數隨濃度之增加而增加,流動行為指標則隨濃度增加而下降。在動剪切測試中發現,於所探討之頻率範圍內,2%及4%桑葉多醣溶液,為濃縮濃液;6%及8%桑葉多醣溶液,其貯存模量(G'')皆大於耗損模量(G"),呈現膠體結構。添加氯化鈉、氯化鉀對桑葉多醣溶液之G'' 及 G"影響輕微,然添加氯化鎂、氯化鈣於桑葉多醣溶液中皆能提高其G'' 及 G"。添加68mM以上之氯化鈣於桑葉多醣溶液,會導致桑葉多醣溶液產生相分離而凝膠;並有離水之現象發生,離水率約為8.52-30.98%。

Polysaccharides were extracted from the mulberry leaves by sodium bicarbonate solutions. Rheological properties of the mulberry leaves polysaccharides and salts addition were studied using Canon-Fensky glass capillary viscometer and dynamic rheometer. It was found that the weight average molecular weight of mulberry leaves polysaccharides was about 690,000, with a Mark - Houwink constant (k×106) and Mark - Houwink expoent in the range of 50.1 and 1.24, respectively. It was found the intrinsic viscosity of mulberry leaves polysaccharides decreased with increasing ionic strength. The salt tolerance was 12.34 to 13.42 ml M0.5 /g. The chain stiffness parameter of mulberry leaves polysaccharides was about 0.004 with mono-valent salts addition, and from 0.003 to 0.0004 with divalent salts addition. The low values of chain stiffness parameter indicated the stiff backbone characteristics of mulberry leaves polysaccharides. The specific viscosity versus concentration plot exhibited a power-law dependence on concentration. The coil overlap parameter of the mulberry leaves polysaccharides was 5.55 to 6.68, and the exponent b ranged from 0.94 to 1.03 in the dilute domain and from 2.09 to 3.06 in the semi-dilute domain. During steady shear measurements, mulberry leaves polysaccharides showed shear thinning behavior, which could be analyzed by a power law model. The consistency index of mulberry leaves polysaccharides increased, and the flow behavior index decreased with increasing concentration. During dynamic shear measurements, within the frequency range tested, results indicated that the storage modulus were greater than loss modulus with 6% to 8% mulberry leaves polysaccharides solution. The mulberry leaves polysaccharides solution can be classified rheologically as those of concentrated solution with 2% to 4% concentration and gel behavior with 6% to 8% concentration depending on the concentration. The storag and loss modulus of mulberry leaves polysaccharides solution increased with increasing sodium, potassium, magnesium, and calcium ion concentrations. The phase-separated network showed less water syneresis phenomenon with calcium chloride addition was 68 to 200 mM.
URI: http://hdl.handle.net/11455/51246
Appears in Collections:食品暨應用生物科技學系

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