| Anthocyanins are a kind of water-soluble natural pigment,belonging to flavonoids.It has attracted extensive attention because of its high value,such as scavenging free radicals,anti-oxidation,anti-aging effect and so on.Anthocyanins exsit many plants,but content is low.The traditional organic solvent method is usually used in the extraction of anthocyanins.But this method has the disadvantages of volatile,long extraction time and large consumption.Deep Eutectic Solvents(DES)is a new solvent developed in recent years.It has many excellent physical and chemical properties such as strong solubility and design ability.There is a large amount of anthocyanins which have highly antioxidant activities in Saskatoon berry(Amelanchier alnifolia Nutt.).In this research,the deep eutectic solvents(DESs)synthesized were used to extract anthocyanins from saskatoon berry.Based on solubility parameters,DL-lactic acid and five different quaternary ammonium salts were used to synthesize several kinds of deep eutectic solvents,respectively.It turned out that the choline chloride/DL-lactic acid(ChCl/LA)showed the best solubility of anthocyanins compared with the other DESs,which was in line with solubility parameter theory.Under the optimized process condition with 1:15 of molar ratio,1:20 of solid to liquid ratio,50°C of extraction temperature and 45 min of extraction time,the extraction amount of anthocyanins reached 525.27±0.82 mg·100g-1 and the extracted rate of anthocyanins was 87.4%.Four different kinds of macroporous resins were investigated in the separation and purification of anthocyanins,and the best was AB-8.And the optimum process conditions were determined as follows: flow rate 1.5 m L/min,eluent is 80% ethanol solution containing 0.1% HCl(pH 4.0).Under the optimum conditions,the adsorption rate(Qre)was reached 87% and the desorption rate(D)reached 80.5% by desorption with 80% ethanol solution of 0.1% HCl.Within experimental error,the recovery yield of anthocyanins can reach 65.7%.The maximum absorption peaks of the purified anthocyanins were obtained by scanning full wavelength with Ultraviolet-visible spectrophotometer(UV).The functional groups and their positions were identified by Fourier transform infrared(FT-IR)and nuclear magnetic resonance(1H-NMR).The peak times and molecular weights of the purified anthocyanins were obtained by high performance liquid chromatography-mass spectrometry(HPLC-MS).The structural identifications were compared with the standard,and then the results show that the measured material chemical structure was consistent with anthocyanins’ characteristics.The research on stability and oxidation resistance of the purified anthocyanins were showed by different aspects.The experiments showed that anthocyanins should be stored in dark conditions with lower temperatures and pH levels about 4.The anthocyanins which extracted from Saskatoon berry showed high activity in scavenging DPPH free radicals,scavenging hydroxyl radicals(·OH)and scavenging superoxide anion radicals(O2-).And they had better ability to reduce iron ions.The buffer solution of ChCl/LA with pH 3.0 was used to take the place of citric acid-Na2HPO4 buffer as the buffer solution and dilution solution in the preparation process of anthocyanin microcapsules by piercing method.And the two of them achieved similar results.The encapsulation efficiency of anthocyanins reach 59.40% under the optimum conditions: the concentration of sodium alginate was 2%,the ratio of core to wall was 1:3,Ca Cl2 concentration was 2%,the size of syringe was 0.3 mm.The structural identification of anthocyanins microencapsule achieved by FT-IR and XRD demonstrated that anthocyanins were embedded sucessufully.In this study,it provided a reference value on the use of new and green solvent for the extraction of natural active biomass.Preparation of anthocyanins microcapsules also provided the basis for the application of anthocyanins in health care products because of good antioxidant activities. |
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