Fabrication Of Flavor Emulsion,oil Powder And Oleogel Based On The Self-assembly Behavior Of Natural Tea Saponin At Oil-water Interface

With the increasing pursuit of the all-natural components and clean label,it is necessary to seek natural emulsifier.As byproduct of camellia oil,natural tea amphiphilic saponin can quickly adsorb on the oil-water interface,and then reduce the interfacial tension,showing a good surface activity.For this study,we first found natural tea saponin?TS?can self-assemble induced by the oil-water interface into a micrometer-scale network and form helical fibrous.Therefore,we used TS as novel building blocks to construct micro-structure system?emulsion,oil powder and oleogel?based on the fibrillar self-assembly of TS and their properties were characterized.More importantly,we investigated relationships between the self-assembly behavior of saponins at oil-water interface,the micro-structure system of emulsion,oil powder and oleogel system and the controlled release of flavor volatiles.These findings would provide theoretical guidance and technical support for the development of new foods,cosmetics,and pharmaceutical products.The main findings of this paper are as follows:?1?Based on the differences among the small molecule structure of saponins,we investigated the self-assembly behavior of natural saponin molecules?Tea saponin,Quillaja saponin,Glycyrrhizic acid and Stevioside?at the oil-water interface and constructed emulsion system,which was compared to a synthetic emulsifier of sodium dodecyl sulfate?SDS?.The study found that the tea saponin?TS?had similar self-assembly behavior with commercial quillaja saponin?QS?at the oil-water interface,where could self-assemble into a micrometer-scale network form helical fibrous.The result of the kinetics of adsorption confirmed that tea saponins showed a significantly lower CAC?0.206 mg/m L?and a higher interfacial diffusion coefficient than of other natural saponins and SDS,and could effectively reduce interfacial tension,resulting in good emulsifying properties and emulsion stability.Moreover,the self-assembly fibrillar network of TS played an important positive barrier and significantly reduced the release of flavor volatiles(low V₀ and C_max).?2?According to the self-assembly fibrillar network of TS at the oil-water interface,we for prepared phytosterol-rich flavor emulsion and oil powder by one-pot ultrasonic strategy.It was found that high phytosterol-rich flavor emulsion was successfully prepared with ultrasonic cavity effect energy?280 W,5 min?by one-step ultrasound under an ice-bath environment.With the increase of content for flavor oil and saponin content,especially for peppermint oil and orange oil,the smaller droplets?<420 nm?,and the higher encapsulation efficiency of physterols?up to 88.03%and 92.06%for peppermint oil and orange oil,respectively?were obtained.Compared to the other five traditionally commercial emulsifiers?starch sodium octenyl succinate,sodium caseinate,quillaja saponin,TW80 and lecithin?,TS-stabilized emulsions have good monodisperse,stability;and high encapsulation efficiency of physterols?89.50%?.Then,TS-based microspheres?⁵?m?of oil powder were fabricated by simple spray-drying from the flavor emulsion template.Further,the oil powder had good flowability?the angle of repose<40°?,reconstruction and stability.The GC-MS analysis of volatiles from flavor oil powders prepared by different emulsifier-stabilized emulsions confirmed that the interfacial fibrillar network behavior of tea saponins contributed to good encapsulation for volatile compounds.Therefore,TS-based flavor emulsions and oil powders can be used as good carriers for active ingredients and flavors in foods,cosmetics and other fields.?3?The effect of hydrophobic phase on the properties of TS-based high internal phase emulsion?HIPS?gels was evaluated.Furthermore,the structure-controllable organogel with ultra-high oil phase?as high as 95%?was successfully from the TS-stabilized emulsion template.This work showed that the TS-based emulsion gels showed a 3D network microstructure stablilized by unique fibrosis network interfacial film from self-assembly of TS at the oil-water interface,which could provide excellent thixotropy fully recovery and superior thermal stability.When the soybean oil as hydrophobic phase,TS adsorped onto the oil-water interface faster and had a much lower interfacical tensionresulting in a smaller droplet size.Accordingly,the emulsion gels had a denser network microstructure and higher mechanical strength.Moreover,upon water evaporation,the resulting emulsion could be easily convert into a transparent oleogel with a higher mechanical strength?G?up to 10⁵ Pa?and good freeze-thaw stability.As a result,not only the microstructure,mechanical strength and thermal stability of the TS-based emulsion gels,but also the mechanical strength and freeze-thaw property of the TS-based oleogel could be well tunable by the hydrophobic oil phase.