Improving The Stability And Bioaccessibility Of Lycopene Emulsion By Polyphenol-protein-polysaccharide Conjugates

Lycopene possesses anti-oxidant,anti-inflammatory,and anti-cancer properties.However,its polyunsaturated characteristics results in its low solubility and poor bioavailability,and easily being degraded under pressure of light,oxygen,heat and p H,which limits its application in food,medicine and cosmetics industries.Delivery system,built by encapsulation,could improve the stability and biological accessibility of lycopene.Therefore,Bovine Serum Albumin(BSA),Chlorogenic Acid(CA)and Dextran(DEX)were selected as raw materials,and encapsulation wall materials,binary(CA-BSA,BSA-DEX)and ternary((CA-BSA)-DEX)covalent complexes,were prepared through alkali treatment and Maillard reaction.Emulsion delivery system rich in lycopene was prepared through ultra-high pressure homeginazition.The structure and functional properties of conjugates were revealed,and also the stability,antioxidant activity and biological accessibility of emulsion system were discussed.Results of SDS-PAGE electrophoresis and Fourier transform infrared spectroscopy(IR)showed that CA/DEX covalent bound with BSA and subsequently reduced the amount of free amino groups in BSA and resulted in the maximum grafting degree of CA-DEX-BSA being 31.45%;IR and fluorescence spectroscopy results showed CA/DEX covalently binding with BSA irreversibly changed BSA’s secondary structure and tertary structure,lowered the hydrophobicity of BSA;The emulsifying property and stability of BSA were modified by CA and DEX and subsequently increased to 85.86±1.19 m~2/g and50.75±1.87 min,respectively.The foamability was significantly reduced to 66.12±1.21%,but foam stability was significantly enhanced.Droplet size,potential and retention rate of lycopene were analysised.It was found that the encapsulation rate of lycopene emulsion stabilized by(CA-BSA)-DEX covalent complex could reach to 70.85±1.52%,but its particle size was only 175.2±1.21 nm The sucrose stability and ionic strength stability of BSA stabilized system modified by polyphenols were higher than those of pure protein stabilized system,and the emulsion system of(CA-BSA)-DEX covalent complex is more stable.When the emulsion was stored at different p H and temperature,the degradation rate of lycopene was lower in acidic environment and low temperature,and the particle size of the emulsion modified by polysaccharide changed little and was more stable.The antioxidant activity experiment showed that the covalent complex with polyphenols had stronger DPPH radical scavenging ability,ABTS+radical scavenging ability and reducing power.The simulated gastrointestinal experiment showed that with the digestion process,the particle size of emulsion increased gradually,and the particle size of BSA stabilized lycopene emulsion changed the most.The retention rate of lycopene in emulsion system with(CA-BSA)-DEX covalent complex was the highest,that is,the highest biological accessibility.