Studies On The Mechanism Of Extracting High Gelation Property Carrageenan From Hypnea

Carrageenan is used widely in food industry, but in mainland its production is mainly dependent on import resources. For the purpose of using domestic rich Hypnea resource as the substitution of Eucheuma to producing Carrageenan, a systematic research is made on the extraction mechanism of Carrageenan from Hypnea and characteristic of the product in this thesis. The results are mainly as follows:1.Hypnea thallus is consist of cortical and pith cells, its cell wall includes middle lamella, primary cell wall and second cell wall, while Carrageenan as a cell linkage material, locates in middle lamella between the primary cell wall, with a amorphous status. The main component of Hypnea is carbohydrates, its content in Hypnea from Yangjiang and Hainan is 5% lower than that Eucheuma, but the cellulose content in Hypnea is higher.2. There are three steps in Carrageenan extraction from Hypnea: alkali pretreatment, extraction and purification. By using alkali pretreatment, the wax of corneous layer on the surface of thallus can be removed, cortical cells are damaged. The run-off of middle lamella and intracellular content in pith cells is also observed, which leads to the shrinkage and separation of cell. The thallus is also broken. Comparing with other alkali reagent, KOH has a best effect on the maintenance of thallus structure, extraction efficiency and gel strength of extracted Carrageenan. A model is constructed to describe the action of potassium ion on cell wall of Hypnea. When potassium ion has entered the thallus tissue, it can help building additive bond-bridge in the double-helix structure of Carrageenan, which is beneficial for the linkage of Carrageenan molecular. So the resistance ability of middle lamella to extra cellular environment is increased, the integration of thallus can be kept, and the run-off of Carrageenan can be restrained.After alkali treatment on Hypnea thallus, sulfate on C6 site of Carrageenan molecular is removed, 3,6-anhydro-galactose content is increased, then its conformation is transformed to helix-compatible type, which has been...