Study On The Curcumin Loaded High Concentrated EPI Emulsion And Its Application In Emulsified Sausages

With the development of social economy,people pay more and more attention to the health of diet.Curcumin is widely used as a nutraceutical for food and medicine because of its anti-cancer,anti-oxidation and anti-inflammatory effects.However,curcumin is a strong hydrophobic molecule,which makes the bioactive curcumin have poor permeability on the intestinal mucosa.At the same time,curcumin is sensitive to photothermal oxygen and other conditions,which is also greatly limits the application of curcumin.Research has shown that embedding curcumin crystal particles in lipid droplets can protect curcumin,and reduce its chemical degradation in human water environment,as well as improving its bioacceptability.Therefore,the safe and economical plan of embedding curcumin in emulsion has attracted more and more researchers' attention.The use of curcumin loaded emulsion to prepare gels as a fat substitute for low-fat emulsified sausages is in line with the pursuit of modern people's healthy diet.At present,the research of curcumin loaded emulsion has covered conventional emulsion,nano emulsion and Pickering emulsion.The size of emulsion droplet,the type and concentration of oil phase all significantly affected the embedding effect of curcumin.However,most of the existed studies have introduced organic solvents such as ethanol or curcumin in the preparation process.Therefore,in this study,the EPI(egg white protein isolate)and linseed oil was used as raw material,and the appropriate emulsifier-embedded curcumin was prepared from egg albumin isolate and flaxseed oil,taking the speed of dispersing homogenizer and oil concentration as factors.The effect of high-concentration emulsion on the bioavailability of curcumin was explored under different curcumin concentration.Finally,the prepared emulsifier was used to the emulsified sausage to explore its role in the complex minced meat system.The results of three parts are as follows:1.Study on the effect of different homogenizer speed and oil phase concentration on the high concentration emulsion system of egg white protein separationThe rheological properties,particle size distribution and electrical conductivity of the high-concentration emulsion of egg white protein were determined,and the microstructure of the emulsion was analyzed to study different oil phases(65%?70%?75%?80%?85%(w/w)),the effect of different high-speed shearing speeds(9000,10500,12000,13500,15000r/min)on the structural characteristics of high-concentration emulsion of egg white protein isolate.The results showed that the average particle size of the emulsion droplets increased with the oil phase concentration at the concentration of 65%,70%,75%(w/w)of the oil phase at 6%(w/w)of the egg white protein isolate.When it becomes smaller,the degree of flocculation of the droplets in the emulsion increases,thereby causing an increase in the viscosity and storage modulus of the emulsion as a whole,and the oil droplets begin to be tightly compressed to exhibit a polygonal shape.At 15000r/min shearing speed,the viscosity,the storage modulus,the average particle size of the oil droplets were not significantly changed compared to the values of 13500r/min.At 13500 r/min shearing speed and 6%(w/w)egg white protein concentration,the average particle size of the emulsion oil droplets decreased with the increasing of oil phase concentration from 65%to 75%(w/w),along with the increasing degree of flocculation evidenced by the increase in the viscosity,storage modulus,and the degree of compressed polygonal shape.At an oil phase concentration of 80%(w/w),the average particle size of the emulsion droplets becomes smaller but the particle size distribution becomes wider with decreased viscosity,but the storage modulus increases,and some of the proteins in the emulsion are polymerized together.The emulsion appears gelatinous.The emulsion at 85%(w/w)oil phase concentration will have a large number of proteins that do not take part in structuring.The proteins are randomly aggregated and separated from the oil phase,and the emulsion becomes unstable.2.Study on the effect of high-concentration EPI emulsion embedding curcumin on improving the bioavailability of curcuminBased on the high-concentration emulsion prepared in Chapter 1,the curcumin was dissolved into linseed oil by ultrasonic cell disruption to get a high concentration emulsion loaded with curcumin.At different curcumin concentrations(800,900,1000,1100,1200mg/L),the dispersity,antioxidant and bioacceptability of curcumin were studied by measuring solubility,DPPH clearance rate and bioacceptance(FB)of emulsion and gels.At 13,500 r/min homogenizer speed,6%(w/w)of egg white protein isolate and 75%(w/w)of oil phase concentration,solubility of curcumin in linseed oil was significantly increased and the DPPH clearance rate in the emulsion changed significantly when 800,900,1000,1100 mg/L curcumin was added.The content of curcumin increased obviously in the mixed micelle phase after the digestion of EPI emulsion.When the concentration of curcumin in the emulsion oil phase reaches 1200 mg/L,both the DPPH scavenging ability of the emulsion and the increase of the curcumin content in the mixed micelle phase after digestion are obviously slowed down because the solubility of curcumin in linseed oil is saturated.3-Application of curcumin-ovalbumin high-concentration emulsion in low-fat emulsified sausagesThe curcumin loaded EPI emulsion obtained in the previous two chapters was used as a fat substitute to replace 25%,50%,75%,100%of the pig's back fat during the processing of emulsified sausages,and evaluate water-holding capacity,color,texture characteristics and bioavailability(FB)of curcumin after digestion.The experimental results showed that the use of EPI high-concentration emulsion as a fat substitute will change the quality and characteristics of the emulsified sausages.As the proportion of fat substitutes increases,the cooking loss of the emulsified sausages is significantly reduced and the water retention is increased.In the determination of color,the L*value of emulsified sausages increased with the increase of emulsion replacement ratio,a*and b*was significantly different from the control group.Texture characteristics showed that 75%substitution ratio was the best.In the emulsified sausage digestion experiment,curcumin obtained from simulated digestion of linseed oil per unit mass was regarded as effective load standed.The results showed that bioavailability of the obtained curcumin is slightly lower than that of the second chapter gel,but higher than the high concentration emulsion of the EPI.Therefore,we infer that the gel structure can further protect the curcumin from being degradated during physiological operation.