Stability And Bioavailability Of Whey Protein-based Ginsenoside Rg3 Nanoemulsion

This research is supported by the“13.5”National Keypoint Research and Invention Program?2017YFD0400603?,and the Jilin Province Provincial School Co-construction Project?SF2017-6-4?.Ginsenoside Rg3 is one of the main active ingredients of ginseng.It has the effects of inhibiting tumor neovascularization,anti-fatigue,regulating immunity,preventing tumor recurrence,spread and metastasis.However,ginsenoside Rg3 has strong polarity,poor water solubility,slow dissolution rate in vitro,and slow oral absorption,resulting in low bioavailability.As the main component of whey,whey protein has the characteristics of rich nutrition,easy digestion and absorption,and high biological titer.The use of whey protein nanoemulsion to carry the active substance can maintain the stability of the active substance.The amphiphilic nature of whey protein enables hydrophobic substances to be carried by nanoemulsions,and can effectively improve the carrying efficiency and bioavailability of active substances.In this paper,whey protein-based ginsenoside Rg3 nanoemulsions were prepared using high-intensity ultrasonic technology to study the processing stability,storage stability,and bioavailability of whey protein-based ginsenoside Rg3 nanoemulsion.The main research contents include the following aspects:?1?90%?v/v?separated whey protein was used as the water phase,and 10%?v/v?medium-chain triglyceride was used as the oil phase.Ginsenoside Rg3 nanoemulsions were prepared by high-intensity ultrasound technology under neutral conditions.They were used to study its physical and chemical properties and processing stability.The obtained nanoemulsions were non-Newtonian fluid,which were thinned by shear and had an embedding rate of more than 70%,of which the 5%WPI-stabilized nanoemulsion had an embedding rate of 87%.The effects of processing conditions?pH,salt ion,freeze-thaw cycle,thermal treatment?on the stability of ginsenoside Rg3nanoemulsions were studied.When the pH is around 5,affected by the isoelectric point of whey protein,the protein aggregated and the particle size increased significantly.At lower or higher pH,the nanoemulsions had good stability.When the WPI concentration was 5%,the particle size was 321.1 nm,the zeta potential was-59.7 mV,the turbidity was 259.4 cm^-1,and the K value was 28.1%.The oil droplets of nanoemulsion had a thick interface film on the surface,the particle size of the droplets did not change significantly under the influence of Na⁺strength,and the ion stability was good.Freeze-thaw cycle separated water and oil.The particle size,zeta potential,turbidity,and K value of the 5%WPI stabilized nanoemulsion showed the smallest decrease,and the freeze-thaw stability was better.After the ginsenoside Rg3nanoemulsion was heat-treated at 60?,80?,and 100?,protein and fat droplets became more tightly bound,and stability was improved.In general,when the WPI content is 5%,the processing stability of ginsenoside Rg3 nanoemulsion is the best.?2?The 5%WPI stabilized ginsenoside Rg3 nanoemulsion was stored at 4?,25?,and 37?for 7 weeks,respectively.The effects of storage conditions on the stability of ginsenoside Rg3 nanoemulsion were investigated by using ginsenoside Rg3 entrapment rate,particle size,and potential as indicators.After seven weeks,the embedding rates of nanoemulsions stored at 4?,25?and 37?were 56.0%,68.3%and 75.1%,respectively?p<0.05?.Under the storage condition of 4?,the particle size of nanoemulsion increased by less than 3%,the K value decreased by 3.2%,the embedding rate of ginsenoside Rg3 decreased by 11.85%,the potential and turbidity did not change significantly,and the range of change was significantly less than that of samples stored at 25?and 37?,showing better physical and chemical stability.Therefore,the ginsenoside Rg3 nanoemulsion is suitable for longer storage at a low temperature environment of 4?.?3?A ginsenoside Rg3 nanoemulsion in vitro digestion model was established to study the effect of WPI concentration on ginsenoside Rg3 nanoemulsion in vitro digestion and absorption.Investigate the changes in the physicochemical properties of the emulsion during the digestion process,and further verify the choice of the previous emulsifier.The particle size of the nanoemulsion did not change significantly in the simulated gastric fluid,but increased sharply in the simulated intestinal fluid.The particle sizes of 1%,3%and 5%WPI stabilized nanoemulsion samples in intestinal liquid were 1156.2 nm,938.2 nm and 873.9 nm,respectively?p<0.05?.It was because that WPI was hydrolyzed by trypsin.The retention rate of ginsenoside Rg3 decreased slightly with the progress of digestion.Among them,the 5%WPI stabilized nanoemulsion had the highest retention of ginsenoside Rg3 in the initial,simulated gastric fluid,and simulated intestinal fluid,which were 86.95%,79.53%,and 75.75%,respectively.After simulated gastrointestinal digestion,the bioavailability of ginsenoside Rg3 was also the highest,reaching 55.3%.The particle size of 5%WPI stabilized nanoemulsion was always the smallest,and the bioavailability was negatively correlated with the particle size.