Characterization Of The Modified Anthocyanins Liposomes From Purple Sweet Potato

Anthocyanin is a natural edible pigments which has excellent properties,but anthocyanin stability is poor,thus the scope of its application was limited.In this study,soybean lecithin was used as the main wall material,and anthocyanin liposomes were prepared with purple sweet potato anthocyanin as core material.And the prepared anthocyanin liposomes were modified with polysaccharides.The physicochemical properties of the system,the in vitro release characteristics and the stability of the liposomes in gastrointestinal environment were simulated.On this basis,the mechanism of the polysaccharide modified liposomes and the effect of the modified compounds on the liposome structure were further studied.First,purple sweet potato anthocyanin liposomes were prepared and optimized.The optimum formulation was as follows:the ratio of core to fat was 21:1,the ratio of lecithin to cholesterol was 6:1,the dosage of surfactant was 10:4,At the temperature of 50 ℃,ultrasonic time is 3min,the encapsulation efficiency was reached 47.24%and the loading was 2.25%.The particle size of purple sweet potato anthocyanin liposomes was(214 ± 12)nm,the potential was(0.50±0.39)mV,the density wasl.086g/mL,the viscosity was(4.73±0.02)centipoise,the surface tension was(51.0±2.1)mN/m.The antioxidant capacity of purple sweet potato anthocyanin solution and purple sweet potato anthocyanin liposomes were compared.The results showed that there was no significant difference in the ability of anthocyanin liposomes with anthocyanin aqueous solution,and positively correlated with the concentration of anthocyanins.The stability of anthocyanin liposomes measured by a stability analyzer.The results showed that anthocyanin liposomes were stable.(CMC-LP),sodium alginate modified liposomes(AL-LP),pectin-modified liposomes)were prepared by using different concentrations of polysaccharides to modify purple sweet potato anthocyanin liposomes.The changes of particle size of liposomes modified by three kinds of polysaccharides were basically the same,and their particle size gradually increased with the increase of polysaccharide concentration.However,with the increase of polysaccharide concentration,the change of zeta potential was decreased first and then stabilized.When the viscosity was measured,the viscosity of the pectin-modified liposomes was not changed,and the viscosity of the sodium alginate-modified liposomes increased gradually with the increase of the concentration.The surface tension of the sample is 50.1mN/m,and the concentration of modified polysaccharide tends to decrease.Storage stability and in vitro release properties of modified liposomes:Liposome production can significantly improve the stability of anthocyanins.While the polysaccharide modified liposomes can further improve the storage stability of anthocyanins.There was no significant difference between different polysaccharides modified liposomes.The results of in vitro release showed that the delayed release of anthocyanin liposomes was significant.The stability of anthocyanin liposomes in vitro simulation gastrointestinal environment:four different concentrations of polysaccharide solution modified and unmodified liposomes,after digestion in vitro for a certain period of time in the simulated intestinal environment,The content of the anthocyanin will be significantly reduced.The stability of carboxymethyl chitosan-modified liposomes and unmodified liposomes in vitro simulated intestinal environments is not obvious.Among the three liposome samples,0.4%sodium alginate-modified liposomes had the highest levels of anthocyanin residues,followed by 0.3%pectin-modified liposomes.The stability of liposomal samples in the stomach environment is significantly higher than in the intestinal environment.After three kinds of polysaccharide modified liposomes can significantly improve the stability of anthocyanins in the stomach.The effect of polysaccharides on the forces and structure of liposomes:The infrared spectra show that the hydrogen bonds was generated on the lipophilic bilayer interface or the hydrogen bond was enhanced.While the chemical bond was not changed in the bimolecular layer,so,anthocyanin structure has not changed.The Raman spectra show that the modification of polysaccharides can induce the increase of transpositions of liposomes,and the accumulation of hydrocarbon chains is close,and the order of the chain is increased.,the lateral accumulation between molecules of Liposomes modified by sodium alginate is still closed.However,the lateral accumulation order of pectin-modified liposomes will be reduced compared to the blank liposomes.