Research On Extraction Of Carrageenan From The Eucheuma By Ultrasonic-assisted Alkali Treatment And Its Application Of Film

Carrgeenan which is also called the antlers algin or canageenin is extracted from some red algaes such as chondrus,eucheuma,gigartina and hypena.It is a kind of polysaccharides mixture with great economic value.As it is good in water-solubility(completely dissolved at 80 ?),gelling,thickening,emulsifying,film,non-toxic and other abilities,carrgeenan is often used as a food gum in food industry.For example:it has been widely used in dairy products,ice cream,fruit juice,bread,jelly,meat,spices,etc.The lastest study in medical applications had shown that the degradation of carrageenan products had anticoagulant,antitumor,antiviral activities,and so on.Therefore,the carrageenan industry developed rapidly.Now,as the market share of carrageenan in drug'packaging industry accounted for more than 80%,so the suitable production of carrageenan with has great potential in the market.The NaOH and KCl were mixed to pre-treat the raw materials in the traditional carrageenan production methods,but the gel strength of carrageenan proved to be weak and the sulfate group content was high(more than 25%),which limited the usage and development of carrageenan in packaging and film field.This dissertation mainly explored the effect of ultrasound in the alkali treatment based on NaOH instead of NaOH-KCl.And then research and analysis PVA-CG blend film that based on the film-forming properties of carrageenan.The carrageenan and PVA-CG film was characterized and analyzed by the test analyzer of FTIR,SEM,and TG.The main results were as follows:The experiments used high temperature-dilute method at 80 ?.Then,the yield of carrageenan,gel strength,and sulfate groups content were investigated by controlling alkali concentration,ultrasonic frequency,sonication time.The results showed that the ultrasound added in alkali treatment could cause exudation of colloid when the alkali concentration was less than 4%,so it was better to control the concentration of alkali at above 6%.Then after the single factor test,we researched the combined effects of alkali concentration,ultrasonic frequency,sonication time on the carrageenan of yield,gel strength,and sulfate groups by the response surface methodology with the determine range of alkali concentration,ultrasonic frequency and sonication time.And the results showed that the best conditions of alkali concentration,ultrasonic frequency and sonication time were 8%,24KHz,2h,respectively.Under this condition,gel strength,sulfate groups content were 54.72%±1.46%,1310.00±18.31,15.44%±1.04%,respectively.Finally,the properties of tensile strength,elongation at break,thermal stability were analyzed based on current research situation which the film was prepared by the PVA-CG film added BaCl2or soaked in BaCl2 solution.The results showed that the tensile strength of film would significantly reduce,and surface of film became crude by adding BaCl2 directly.However the elongation at break was increased.The PVA-CG film had good tensile strength and elongation at break when the addition amount between at 8.75%and 17.50%(the mass percent in film).In addition,the film would be better in tensile strength and elongation at break that reached at 24.22Mp and 47.99%when the PVA-CG film was soaked for 1h in BaCl2 solution.