Study On The Stability Of Self-assembled Chitosan Pickering Emulsion For Loading Beta-carotene

Bioactive components such as vitamins,polyphenols and polyunsaturated fatty acids have effect on regulating human physiological function,but they have some problems with poor stability,sensitivity to environmental factors and low bioaccessibility.The encapsulation and delivery of bioactive components has become the urgent needs to solve the problem.The Pickering emulsion based on food-grade micro-nano-sized particles has the potential to become an effective carrier for active ingredients because of its high stability,large interfacial thickness and no need for surfactants.Chitosan,which is one of the few amino polysaccharides of biological origin,can be utilized to prepare micron-nano-sized gel particles only by adjusting its p H value without physical and chemical modification.The self-assembled chitosan particles can be used to prepare Pickering emulsion with good storage stability,but there are relatively little reference on the encapsulation of bioacitve components.To explore the encapsulation ability of the Pickering emulsion,this paper chose beta-carotene as experimental object and systematically studied the effect of self-assembled chitosan Pickering emulsion on the stability of beta-carotene.Self-assembled chitosan particles can be used to prepare more stable Pickering emulsion at high p H value because of higher hydrophobicity.However,when chitosan is deprotonated at high p H value,the particles tend to agglomerate into large particles due to the weakening of electrostatic repulsion,which affects the formation of emulsion.In order to reduce the particle size and enhance the stability of emulsion,Self-assembled chitosan Pickering emulsions loaded with beta-carotene were prepared by ultrasound and high-pressure homogenization.The physical stability of the emulsion and the degradation chemical stability of beta-carotene were characterized by means of emulsion microscopy,macroscopic emulsion photographs,Zeta-potential,UV light stability and thermal stability.The effects of the concentration of chitosan solution,the p H value of chitosan solution,the volume fraction of oil phase,the ultrasonic power and time,the high pressure homogenization pressure and high pressure homogenization times on the physical stability of emulsion and the chemical stability of beta-carotene were systematically studied and the optimal treatment conditions were obtained.The optimal treatment conditions for self-assembled chitosan Pickering emulsion loaded with beta-carotene prepared by ultrasound: the concentration of chitosan solution is 1 wt%,the p H value of chitosan solution is 6.5,the volume fraction of oil phase is 20%,the ultrasonic power is 450 W,and the ultrasonic time is 3 min.The optimal treatment conditions for self-assembled chitosan Pickering emulsion loaded with beta-carotene prepared by high pressure homogenization: the concentration of chitosan solution is 1 wt%,the p H value of chitosan solution is 6.5,the volume fraction of oil phase is 20%,the high pressure homogenization pressure is 90 MPa and the times of high pressure homogenization are 6 times.These two methods can prepare self-assembled chitosan Pickering emulsion loaded with beta-carotene with good stability.Finally,the physicochemical stability of emulsion and the bioaccessibility of beta-carotene prepared by ultrasound and high pressure homogenization under the optimal treatment conditions were studied comparatively.The study found that the emulsion droplets treated by high pressure homogenization had smaller particle size and more uniformity than that of ultrasonic treatment,and its UV light stability and thermal stability were better than that of ultrasonic treatment.The bioaccessibility of beta-carotene in the emulsion prepared by high pressure homogenization was slightly better than that of conventional Tween emulsion,while the bioaccessibility of beta-carotene in the emulsion prepared by ultrasound was slightly lower than that of conventional Tween emulsion.As a whole,self-assembled chitosan Pickering emulsion was a good choice for encapsulating beta-carotene because the emulsion had the advantages of good physical stability and chemical stability and high bioaccessibility.