| Emulsion carriers are widely used for loading bioactive substances,preventing the degradation of the active substance and controlling the release of the active substance to improve bioavailability.In this paper,three emulsion systems were constructed to study the physical and chemical stability of the emulsions and to analyze the effects on the retention and bioaccessibility of β-carotene in the hope of improving the scope of application of β-carotene in the food industry.The physicochemical properties,stability and digestive characteristics of the different emulsions were investigated by preparing protein emulsions,mixed interfacial emulsions and Pickering emulsions.The main conclusions were obtained as follows.(1)Sodium caseinate emulsions and soybean isolate protein emulsions were prepared by ultrasonic emulsification,and it was found that both protein emulsions showed delamination flocculation when the emulsion p H was below 5,and both remained stable at p H 7.Good thermal stability of both protein emulsions.With the increase of salt ion concentration,the particle size of soybean isolate protein emulsion increased to about 1300 nm,reduced potential values of sodium caseinate emulsions,soybean isolate protein emulsions.The retention of β-carotene in sodium caseinate emulsion,soybean isolate emulsion and oil was 52.44%,59.30% and 46.06%,respectively,when stored at 37 ℃ and protected from light for 14 days.The release of free fatty acids in sodium caseinate emulsion,soybean isolate protein emulsion and pure oil was 99.82%,97.35% and 90.26%,respectively,and the bioaccessibility of β-carotene was 10.93%,9.8% and 8.28%,respectively,by simulated in vitro digestion experiments.The experimental results showed that the stability of sodium caseinate emulsion was better than that of soybean isolate protein emulsion,and the two protein emulsions had a protective effect on β-carotene,which could accelerate the digestion rate of fats and oils and improve the bioaccessibility of β-carotene.(2)In order to improve the stability of soybean isolate protein emulsion,Tween-80 was selected to mix with soybean isolate protein to prepare mixed interfacial emulsion,and it was found that with the increase of Tween-80 content,the particle size of the emulsion decreased,and the droplet size gradually decreased from about 488 nm to 225.7±15.98 nm.As the Tween-80 content increased,p H,heating treatment,and salt ion concentration had no significant effect on the stability of mixed interfacial emulsions.The retention of β-carotene in the emulsion decreased when stored at 37 ℃for 14 days at constant temperature and protected from light,and the retention of β-carotene in the mixed interfacial emulsion was 50.89% when the Tween-80 content was 0.4%.By simulating in vitro digestion experiments,the bioaccessibility of β-carotene increased from 9.7% to 11.8% with increasing Tween-80 content and accelerating the release rate of free fatty acids from the emulsion.The experimental results showed that the increase of Tween-80 content increased the stability of mixed interfacial emulsions,decreased the retention of β-carotene and improved the bioaccessibility.(3)To further investigate the stability of picolinic emulsions related to sodium caseinate,nanoparticles were prepared by self-assembly of chitosan,pectin and sodium caseinate,and the particle size of both nanoparticles increased with increasing p H,while salt ion concentration and heating treatment had no significant effect on the stability of nanoparticles.Pickering emulsions were prepared with 0.5% nanoparticles and 50% oil phase,and it was found that the freeze-thaw stability of sodium caseinate-chitosan pickering emulsions was superior to that of sodium caseinate-pectin pickering emulsions.The retention of β-carotene in sodium caseinate-pectin pickering emulsion,sodium caseinate-chitosan pickering emulsion and pure oil was 70.46%,67.11% and55.43%,respectively,after 7 days of UV light treatment.By simulating in vitro digestion,the release of free fatty acids in sodium caseinate-pectin pickering emulsion and sodium caseinate-chitosan pickering emulsion was 88.32% and 86.12%,respectively,and the bioaccessibility of β-carotene in sodium caseinate-pectin pickering emulsion and sodium caseinate-chitosan pickering emulsion was 22.31% and25.14%,respectively.The experimental results showed that Pickering emulsion could improve the UV stability,bioaccessibility and delay the release of free fatty acids of β-carotene. |
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