| Taurine is a semiessential amino acid that is not incorporated into proteins. In human body, taurine is ubiquitous and is the most abundant free amino acid. Taurine plays a significant role in many essential biological processes. Nowdays, with our increasing recognition of the importance of taurine, it has been widely added in cosmetics, energy drinks, medicaments, baby and formula powders. As the demand of taurine is increasing, it is extremely urgent for us to explore new ways to obtain taurine. Porphyra yezoensis is widely cultivated in Jiangsu province of china. It is striking that P. yezoensis contains taurine in a remarkably high amount, about 1% of dry weight.In this article, we study the technology of extracting taurine from P. yezoensis in order to provide some scientific message for the comprehensive utilization of nori and explore a new method to produce taurine. Firstly, we developed a new way to determinate the content of taurine in P. yezoensis. Secondly, taurine was extracted from P. yezoensis by ultrasound assisted procedure. Through chitosan flocculation, membrane filtration, ion-exchange chromatography, taurine was purified. The main results as following:1. A new method was developed to determine taurine of P. yezoensis by high-performance liquid chromatography. o-phthalaldehyde (OPA) was derivative, the reaction of OPA and taurine finished in 2 min at room temperature. The separation was performed on a XDB C18 (150 mm×4.6 mm,5μm), the mobile phase was methanol-solution of sodium acetate(pH 5.3,43:57) at the flow rate of 1 mL/min. The taurine was detected at 315 run and 30 ℃. The taurine could be well separated with a good linear relationship in the range of 5.0～30.0 μg mL-1(R2=0.9991). The average recovery (n=6), RSD and detection limit were 98.8%,1.8% and 0.25 μg mL-1, respectively. The proposed method had high precision and sensitivity and was not interfered by other complex components. With the most amount of taurine, P. yezoensis of the third collection period was the perfect material to extract taurine.2. Ultrasound-assisted procedure was used to extract taurine from P. yezoensis. Box-Behnken experimental desighn and response surface methodology were applied to investigate the effects of time, power and temperature on taurine concentration. A cubic model was built. The optimum process conditions were determinate as 3 h,300 W,80℃,2 times, under optimum process conditions, the extraction rate of taurine was 11.26 mg/g dry weight.3. Chitosan flocculation can efficiently remove polysaccharide and protein in taurine extraction. Effects of chitosan dosage, pH and settling time were investigated. Flocculation at optimum conditions,93.82% protein and 80.00% polysaccharide were removed. The optimum flocculation conditions were the chitosan concentration was 250 mg/100 mL, pH 2.5, at optimum conditions floccution can finish in 10 min. removing subtotal protein and polysaccharide, chitosan flocculation accelerates membrane filtration and makes it easy.Membrane filtration can further efficiently remove protein and polysaccharide. Effects of different pore diameters were studied. The results showed that after permeating through 0.1 μm,10K, 1K polyethersulfone membranes by turns, the removal rate of protein was 82% and polysaccharide was 46%, the recovery of taurine was 91%.4. Animo acids analysis confirmed that 732 cation exchange resin can separate taurine from other amino acids in P.yezoensis extraction. The optimum operation conditions were pH3, sample concentration 1663 μg/mI, the sample rate 1 BV/h, the sample volume 10 BV. The 732 ion exchange resin was confirmed can be renewed well.5. After concentrating the eluate was crystallized by absolute ethanol (4/1,V/V) at 4 ℃,three times to give white crystals in a yield of 0.7%. The purity of taurine was 95%, determined by HPLC. FTIR, MS, NMR techniques were used to determine the structure of the product and confirmed it was taurine. |
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