Study On Preparation Of Fresh Grscilaria Agar And Agarose

In this paper, the effect of alkali-treatment, bleached acidification, microwaveextraction technology and other aspects were researched systematically during theprocess of agar extraction from the fresh Gracilaria. With ethanol, agar transparencywas improved. We selected EDTA-Na2method as extraction and purification ofagarose, and determine the optimum extraction process to extract high-quality agaroseproducts. The main contents and conclusions are as follows:1．Alkali treatment had a greater impact on the quality of agar in the freshGracilaria agar extraction process. With agar yield and gel strength as evaluation andalkali treatment concentration, temperature, time as impacting factors, we conductsthe single factor experiment to select the appropriate factors and levels. UsingBox-Behnken response surface methodology analyze the significance of alkalitreatment of various factors and the interaction, getting the optimum extractionprocess. The use of a combination of Box-Behnken Center Optimization to get thebest treatment conditions: alkali concentration of7.5%, the alkali treatment time2h,alkali treatment temperature80oC. Under the extraction conditions, the yield of agarwas25.83%and the gel strength of agar was1218g/cm2.2. Yield of fresh Gracilaria agar first increased then decreased with the amount ofacid treatment increased, gel strength had been a decreasing trend. Agar whitenessincreased with H2O2concentration and bleaching time at first then increased the trendstabilized and the first increased then decreased with increasing pH and trend ofbleaching temperature. We got the best bleaching process conditions by orthogonalexperiment as follows: H2O2concentration of1.5%, bleach pH value of12, thebleaching time5min, bleaching temperature40oC, and the whiteness and gel strengthwere45.78,1383g/cm2respectively.3． With Box-Behnken central composite method, the optimum operatingconditions of microwave extraction of agar was obtained as follows: microwave time20min, microwave power1500w, frond fragmentation50%. Under this condition, the agar yield of fresh Gracilaria was31.6%, and the gel strength of agar was1120.8g/cm2.4. Agar was pretreated by ethanol, to improve agar transparency. Ethanolprocessing condition was optimized by using orthogonal experiment. The optimumconditions were as follows: the solid-liquid ratio of1:40, the ethanol concentration of50%, the processing time5h. Under this condition，the agar transparency was50.2%.5. Agarose was extracted from agar by using EDTA-Na2. Concentration ofEDTA-Na2, treatment temperature and treatment time were studied by a single factorexperimental on the sulfate content and gel strength of the gel. We should useorthogonal experiment to determine the optimal extraction process. The optimumconditions: EDTA-Na2concentration of5%, treatment temperature is60oC, theprocessing time is4h. The agarose sulfate content was0.46%, gel strength1268g/cm2.