| Blue algae blooms break out more frequently in Taihu lake, yet the salvage techniques and dehydration techniques of algae were matured. Utilization of the algae has attracted more and more attention. Blue algae is rich in natural pigments such as carotenoids, chlorophyll-a, etc. which could be widely used in food, medicine, daily chemicals and other industries. So extraction of the natural pigments from blue algae, turn waste into wealth, would be a sustainable effective treatment for Taihu Lake. In this paper, taking the blue algae as raw materials, the process of supercritical CO2 extraction for carotenoids has been investigated, and the carotenoids have been separated, purified and identified. Solvent extraction and ultrasound-microwave assisted extraction were applied to extract chlorophyll-a from the extracted carotenoids residue. The preparation, the stability and structural identification of sodium copper chlorophyll also have been studied.Taking the spray drying blue algae as material, supercritical CO2 extraction process for carotenoids was investigated which is aiming for carotenoids yield. The best extraction conditions were obtained by using single factor and Box-Benhnken optimization test as extraction temperature 52℃, pressure 25 MPa, extraction time of 76min, CO2 flow 18 Kg/h. Under such conditions the extraction yield of carotenoids can be up to 0.621±0.009 mg/g. The collected extracts were isolated and purified by the saponification, silica gel column and crystallization, and the purer carotenoid can be obtained. The type of carotenoid was determined toβ-carotene by the analysis of UV, LC/MS, IR and NMR spectra.Taking the residue of supercritical CO2 extraction as material, the extraction process for chlorophyll-a has been studied which is aiming at chlorophyll-a yield. By using single factor and Box-Benhnken optimization test the best solvent extraction conditions were obtained as were 86% ethanol concentration, temperature 69℃, time 6.6 min, liquid-solid ratio of 20:1, extracted 2 times.In this case the extraction yield of chlorophyll-a can be up to 3.216±0.013 mg/g. Meanwhile, by using single factor and Central Composite Design optimization test, the best conditions of ultrasound-microwave coupled extraction process of chlorophyll-a were obtained, which were ultrasound 50 w, microwave power 250 w,85% ethanol concentration, extraction time 156 s, liquid to solid ratio of 15:1, extraction twice, so that the extraction yield of chlorophyll-a can be up to 3.315±0.067 mg/g.The research of sodium copper chlorophyll preparation showed that saponification is more thorough in the saponification temperature 60℃and above 40min. Acidification with copper was more complete in pH 1-2,50℃and above 60 min, and after crystallizing sodium copper chlorophyll was obtained with a yield was 1.91%. By using UV, HPLC, LC/MS and other testing tools, the structure.of sodium copper chlorophyll was identified as Cu chlorin p6. According to the molecular structure and fragments of the molecular ion peak, Cu chlorin p6 ionization mechanism was speculated too.The results of sodium copper chlorophyll stability test showed that the thermal degradation of sodium copper chlorophyll is of zero-order reaction kinetics and the activation energy is 56.35 kJ/mol. The thermal degradation rate increased with increasing temperature, but the half-life decreased. Sodium copper chlorophyll is suitable for preservation under alkaline conditions, and there is little effect from H2O2 and Na2SO3. But sodium copper chlorophyll may be affected by metal ions to a certain extent. Such as the solution of sodium copper chlorophyll turned to yellowish-green after joining in Fe2+ with absorbance tended to increase. And absorption showed a downward trend with adding in Zn2+, Co2+, Mg2+. The higher metal ion concentration is, the more sodium copper chlorophyll degradation happens. Common food additives such as maltose, glucose and sucrose have no impact on the sodium copper chlorophyll, and low concentrations of NaCl can coexist with also.
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