The New Extraction Of Iota-carrageenan From Eucheuma Spinosum And Studies Of Rheological Properties

Carrageenan which is also called the carrageenan or antlers algin is a red algaepolysaccharide mixture with great economic value, which is extracted from red algaesuch as chondrus, gigartina, eucheuma and hypena. Now the carrageenan is widelyused in many fields such as food, medicine and chemical industry. The common typesof the commercialization of carrageenan are mainly kappa-, Iota-and lambda-. In thelatest medical applications, studies have shown that the degradation of carrageenanproducts have anticoagulant, antitumor, antiviral activity, etc. In the pharmaceuticalindustry the vegetable capsule shell grew rapidly, and one of its raw material iscarrageenan which lead to the quantity demand multiplied. Recent studies have shownthat the type of iota-is better than kappa-in many features: kappa-carrageenan gelsare brittle, hard and bleeding. On the contrast, iota-carrageenan gels are flexible, soft,thixotropic behavior, no bleeding and halophilic. These features makeiota-carrageenan has been more widely used value in food, cosmetic, pharmaceuticaland other industries.This study is mainly on the extraction of iota-carrageenan from the eucheumaspinosum, aims to get the optimum process conditions. Improving the original processreduce the use amount of alcohol to decrease the cost of production. Compared thefeatures and rheological properties of different extracted process to get the low costand high quality production, and this can provide theoretical basis for industrializedproduction.(1)The study on the optimization of extraction process and the quality of theiota-carrageenan: Firstly, eucheuma spinosum were alkali-treated with KOH andNaOH-KCl conditions, iota-carrageenan technical indicators of yield, gel strength,viscosity and sulfate group were compared and the results showed that carrageenanwhich is alkali-treated with KOH is better than NaOH-KCl in the aspect of yield and gel strength. Secondly, we confirm the best extraction conditions for iota-carrageenanby single factor and response surface optimization test which is alkali-treated withKOH. And the results showed that the alkali consistency12%, treatment time6h andtreatment temperature32℃are the best conditions. In these conditions the yield is50.16±1.5%, the gel strength is308.76±12.78g·cm-2and the viscosity is174.50±2.25mPa·s. Under the best conditions, we added the glue solution concentration to theprocess including high temperature mixing enrichment and negative pressureconcentrated, and we can know that the second way is better for the quality ofiota-carrageenan. Thirdly, added KCl or CaCl2to the glue solution to reduce theamount of alcohol and the influence is obvious in a certain concentration range.(2)The study on rheological properties of three different extraction conditionsincluding the original process, mixing enrichment and negative pressure concentratedextract. We can find that in the same shear rate, their viscosity of all these carrageenansolutions are increased with rising concentration. With the increase of carrageenansolution concentration, the consistency coefficient K is gradually increasing, and onthe contrary the flow index n decreases and the value of n is less than1. The resultsshowed three kinds of carrageenan solution were demonstrated shear shinning nature.The concentration of iota-carrageenan are increase as the decreasing of temperatureand the increase margin on40℃. In the study of thixotropy, all of the iota-carrageenanare obviously formed a thixotropic loop and the mixing concentrated has the biggerarea than the original process as the negative pressure was basically the same. Theresults prove that with the increase of frequency, G’ and G" are both have a trend ofincrease and at a low frequency, the G’ is lower than G" leading to the systemdominated by viscous, when the frequency increases to a certain value G’ is greaterthan G" and the system dominated by elastic, showing a weak glue. In thedetermination of gel properties, we can known that the gel temperature ofiota-carrageenan is about38℃and the melt temperature is approximately45℃. Thenumerical of G’ and G " have mutations in the process of heating and cooling.