The Gel Property Of Citrus Pectin And Preliminary Study On Ultrasonic Extracting Of Pectin From Eleocharis Tuberosa Peeling Waste

Pectin is a natural additive, which has good physiological functions, physical and chemical features. It is widely used in various industries and currently in short supply. The pectin extracted from citrus peel and other raw materials has good gelation properties. In this paper, citrus pectin pectin as a common, the nuclear magnetic resonance and texture parameters was applied to measure pectin gelation. This paper also carries out a preliminary study of eleocharis tuberosa leather ultrasonic assisted extraction of pectin for broaden the pectin resources.The optimum conditions of low ester pectin gelling:pH=5.0. The ester bonds and glycosidic bonds in pectin could hydrolysis under low acidity, that cause the decrease of gel strength; the repulsive force between the molecules could increase, resulting in lower gel strength under high acidity. The greater the concentration of pectin led to the better gel property. The optimum sucrose addition was15%. Calcium ion addition amount was40mg/g of pectin, excess can produce a pre-gelwhile reducing the gel strength.The optimum conditions of high ester pectin gelling:pH=2.6. Low acidity could cause the formation of localized gels; high acidity could cause the increase of repulsive force between molecules, that reduced the gel strength. The greater the concentration of pectin and the higher temperature led to the better gel property. The optimum sucrose addition was70%.Citrus pectin gels were tested by NMR techniques, the results show that the proton spin lattice relaxation time and the gel strength have a good correlation no matter in low ester or high ester pectin. On another point, it can be proved that ion bonding interaction and hydrogen bonding are the gel forces in citrus pectin in view of the above. It also can be judged from the phenomenon that high ester pectin was easier to gel that hydrogen bonding plays an important role in the forming of citrus pectin gel.Eleocharis tuberosa is a kind of fruits and vegetables with good health care function, and also is a good pectin resource. Currently, the pectin in short supply, need to develop new materials. In this study, pectin was extracted from eleocharis tuberosa peel as raw material with the use of ultrasonic assisted extraction method, and the basic physical and chemical properties of the products were analyzed. Ultrasonic technology can significantly improve the pectin extraction speed, the optimum conditions of ultrasonic assisted extraction:solid-liquid ratio1:30, time40min, the pH value of1.0, temperature70℃. The pectin extracted from Eleocharis tuberose peel belongs to high ester low molecular weight pectin, so it is suitable for the development of pectin food thickener.