Study On Construction,stability And In Vitro Digestion Of Camellia Oil Nanoemulsion

Camellia oil is favored by consumers for its high content of unsaturated fatty acids,various bioactive ingredients（squalene,phytosterols,tocopherol,etc.）and high nutritional value and health benefits.However,because of the high content of unsaturated fatty acids,camellia oil is easily oxidized and rancid and deteriorated,which reduce the quality and nutritional value of camellia oil.Nanoemulsion delivery system to embed camellia oil could protect the quality and nutritional value of camellia oil.Emulsifiers play an important role in the successful preparation of nanoemulsions and proper emulsifiers have a great influence on the properties and stability of emulsions.As far as we know,there are few studies on the preparation of nanoemulsions by combining tea saponin with soy protein isolate as emulsifier.Therefore,in this paper,green and low-cost natural emulsifier soybean protein isolate and tea saponin（SPI-TS）was used as composite emulsifier to prepare camellia oil nanoemulsion by high pressure homogenization technology,and the preparation process was optimized.The stability of camellia oil nanoemulsion under preparation conditions was studied.In addition,the digestion characteristics of camellia oil nanoemulsion were studied by using in vitro simulated digestion model.This article provides a reference for the new application of camellia oil in the food industry,a theoretical basis for the development of a new green and low-cost natural emulsifier,and a reference basis for the full use of camellia seed cake.The main research contents and conclusions are as follows:（1）Study on the optimum preparation technology of SPI-TS camellia oil nanoemulsion.The ratio of tea saponin to soy protein isolate（TS:SPI）,mass fraction of composite emulsifier,mass fraction of camellia oil,and homogeneous pressure（MPa）were studied on the average particle size and polydispersity index（Polydispersity Index,PDI）,zeta potential,turbidity and other properties of SPI-TS camellia oil nanoemulsion.The results showed that the TS:SPI was 2:1,the composite emulsifier mass fraction was 3%,the camellia oil mass fraction was 10%,and the homogenizing pressure was 100 MPa,which was the optimal preparation parameters of SPI-TS camellia oil nanoemulsion.The average particle size of camellia oil nanoemulsion was（198.800±1.558）nm,the PDI was（0.140±0.017）,the zeta potential was（-53.600±0.497）m V,and the turbidity was（3661.224±45.996）cm^-1.The results of transmission electron microscopy showed that the droplets were small in size and distributed evenly in the emulsion system.The rheological properties showed that SPI-TS camellia oil nanoemulsion has good kinetic stability.（2）Study on the stability of SPI-TS emulsion and SPI emulsion and TS emulsion prepared under the same conditions were compared.The Influence of average particle size,ξ-potential and microstructure of the three camellia oil nanoemulsions at different p H（3-9）,ionic strength（0-500 m M）,heating temperature（30-90℃,30 min）,and storage conditions（4℃,25℃,50℃,28 days）were studied.The results showed that the SPI-TS emulsion was stable in the p H range of 5-9;the SPI emulsion was extremely unstable in an acidic environment（p H<7）;the TS emulsion was unstable at p H=3.SPI-TS emulsion could tolerate a certain concentration of salt ions（0-300 m M）,but it was poorly tolerant to high salt environments（>300 m M）;SPI emulsion was poorly tolerant to salt ions.At low concentrations（100 m M）the SPI emulsion started to become unstable.The average particle size,ξ-potential and microstructure of the three emulsions did not change significantly after heating at different temperatures for 30 min,which showed a good thermal stability.SPI-TS emulsion and TS emulsion could be stably stored for about four weeks at different storage temperatures,they had a good storage stability.（3）Study on in vitro simulated digestion of camellia oil nanoemulsion.The results showed that the particle size,theξ-potential of the nanoemulsion changes depend on the type of emulsifier during digestion.The release rate of free fat acids of nanoemulsions after gastrointestinal digestion was SPI-TS（68.46%）>SPI（54.20%）>TS（41.36%）,all of which were higher than 38.51%of the control group（camellia oil）.The results showed that the nanoemulsion delivery system could effectively improve the digestion of camellia oil,and the release rate of free fatty acids of nanoemulsion prepared by composite emulsifier was the highest.