本研究首先對市售的6樣中國果膠及6樣德國果膠進行流變實驗，研究其視黏度、極限黏度、分子量以及在不同pH值、溫度、剪切率下所得的視黏度。結果顯示，果膠屬於剪切稀釋的流體。果膠相對分子量分佈範圍為40~65萬Da之間，極限黏度為1.5~4.5(dL/g)，分子量和極限黏度有一線性關係，分子量越高的果膠其極限黏度也就越大。視黏度和極限黏度也有著視黏度越大極限黏度越大的關係。高甲氧基果膠對於溫度的敏感程度相對於非高甲氧基還低。接著使用工業上常用的酸提取法對柳丁皮進行果膠的提取，藉由改變pH值、萃取溫度及萃取時間來決定得到最佳產率的條件。結果顯示，在pH 2.5、提取溫度90 ℃、萃取時間2小時可以得最佳產率。並對自行萃取的果膠進行FTIR以及GPC的測量，結果顯示，大部份測定出的中國果膠和自製果膠為高甲氧基果膠，而德國果膠則多屬於高低甲氧基差不多的果膠。

In this study, six commercial Chinese pectin samples and six commercial German pectin samples were investigated primary by using rheological experiments such as apparent viscosity, intrinsic viscosity, molecular weight in different pH values, temperature and shear rate. The results showed that aqueous pectin solution are shear-thinning fluids. Pectin’s molecular weight is between 40,0000 and 650,000 Da, and pectin’s intrinsic viscosity is from 1.5 to 4.5 dL/g. Molecular weight and intrinsic viscosity exhibit a linear correlation. The higher the molecular weight of pectin, the greater the intrinsic viscosity of pectin. Apparent viscosity and intrinsic viscosity also have positive linear correlation. High-methoxy pectin is less sensitive to change in temperature than other kinds of pectin. Common acid extraction method to extract pectin by changing the PH value, temperature and extraction time was used to determine the optimum conditions for yield. The results showed that in pH 2.5, extraction temperature 90 ℃, extraction time 2 hours can give the optimum yield. We also performed the FTIR and GPC measurements test, the results showed that our pectin and commercial Chinese pectins are almost high-methoxy pectin and commercial German pectins are almost medium-methoxy pectin.

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