Study On The Extraction, Purification,Properties And The Structure Analysis And Characterization Of Pigment From Fruits Of Rhodomyrtus Tomentosa (Ait.) Hassk

Plant. Rhoddmyrtus tomentosa （Ait.） Hassk, member of the Myrtaceae family,commonly known as rose myrtle, is an abundant evergreen shrub native to Southeast Asiawith rose-pink flowers and dark-purple edible bell shaped fruits. Fully mature fruits of R.tomentosa tast very sweet, slightly astringent, and are rich in polysaccharides, flavonoids,anthocyanins, amino acid and other ingredients. The stem, leaves, fruits of the whole plantcan be used as medicinal material. To our knowledge, the information regarding the mainanthocyanins of R. tomentosa is limited, no systematic and comprehensive study onidentification of this anthocyanin has been found, the object of the present study was to makeresearch on the extraction process and the properties of anthocyanin from R. tomentosa fruits,the purification and isolation of the anthocyanins were also included.1. R.tomentosa fruits had abundant nutrients, the composition of amino acid in the fruitswas appropriate and rich in content, the determintation of the fruits nature was obtainted bytesting the solubility. In order to get the optimal extraction conditions of R. tomentosapigment, full wavelength scanning was used to obtain the maximum absorption wavelength.The effect of extraction time, volume fraction of solvent, material-solvent ratio and extractiontemperature to absorbance were studied, based on the single factor test and the absorbance atthe maximum absorption peak as index, response surface method was used to optimize itstechnique parameters. The optimal condition was showed as follows: The optimal agent isacidified ethanol, The optimized extraction parameters were extraction time3.56h,54.55%（volume fraction） alcohol condition, material-solvent ratio1:22.36and extractiontemperature64.78℃.2.The adsorption and desorption performance of nine macroporus adsorbent resins wereinvestigated for pigments separation from R.tomentosa, a suitable resin was chosen and theadsorption and desorption condition were optimized. The results showed that X-5had highercapacity, at pH3.0, which dynamic adsorption rate was94.36%, desorption rate can reach92%, the pigment produced by this method was dark purple power, and its color value was18.45which was more than nine times of before.3.The physicochemical property, stability under different conditions of food technologyand antioxidant activity determined by in vitro methods（DPPH, ABTS radical, reducingpower assays and ORAC test） of purified anthocyanin from fruits of R.tomentosa （ART） wereinvestigated in this study. The maximum absorption wavelength of ART was516nm. Theresult indicated that this pigment was easily dissolved in acidic aqueous solution or acid alcohol solvent, insoluble or hardly soluble in non-polar solvents. In the buffer solution, ARTwas stable when the solution pH value was lower than4.0. It was found that the red pigmentresistant to common food additives, such as carbohydrate, organic acid, sodium benzoate,potassium sorbate, the pigment was poor resistant to light, heat, reduct, oxide. Its stability tometal ions such as: Zn²⁺, K+, Al³⁺, Na+, Ca²⁺, Fe³⁺, Cu²⁺was good, which could protect orenhance its color while Mg²⁺, Fe³⁺could damage the color. Meanwhile, the pigment ofRhodomyrtus tomentosa fruits showed strong antioxidant activities evaluated by modelsmentioned above.4.Taking directional recation targeted to improve the the myrtle pigment stabilityweakened by some adverse factors, the resistance to oxidation and reduction of pigmentsproduced by the reaction was significantly enhanced; gallic acid have hyperchromic effect;low concentration of Mg²⁺, Al³⁺, Fe³⁺solution introduced a hyperchromic effect to thepigment, higher concentration have adverse effect on the reaction pigment.5.The major six compounds were further isolated from the anthocyanin extract bysemi-preparative HPLC and Sephadex LH-20column chromatography, and then identified byHPLC-ESI-MS and nuclear magnetic resonance spectroscopy （NMR）, Amongst,Cyanidin-3-O-β-glucoside and Peonidin-3-O-glucoside were the most abundant antocyanins.