Preparation And Application Of Zein/Carboxymethyl Dextrin Composite Nanoparticle Particles On Pickering Emulsions

Pickering emulsion is the emulsion stabilized by solid particles,which is resistant to coalescence and has strong stability.Pickering emulsion can be used as a delivery carrier for active substances and has the potential to become functional food ingredients of new generation.Zein is a kind of amphiphilic hydrophobic proteins,which exhibits excellent biocompatibility and can be self-assembled to form nanoparticles as emulsifiers for Pickering emulsions.However,single protein solid particle stabilized emulsion is easy to aggregate and stratify,and difficult to be applied in food systems.In this study,carboxymethyl dextrin was used to regulate the wettability of zein to construct composite nanoparticles with controllable hydrophobicity,which were used to stabilize Pickering emulsion,and emulsion gel was designed by using carrageenan combined with covalent cross-linking,which was used as a fat substitute in sausage production.1.Zein/carboxymethyl dextrine nanoparticles(ZCPs)were prepared based on the electrostatic interaction between zein and carboxymethyl dextrin.The structure of ZCPs was characterized by X-ray diffraction,fluorescence spectra,fourier transform infrared spectra and transmission electron microscopy.The results showed that ZCPs with negatively charged and the smallest particle size(212 nm)were formed when the mass ratio of zein to carboxymethyl dextrin(CMD)was 2:1.ZCPs formed were spherical.The results were also proved that the electrostatic interaction and hydrogen bonding were the main driving forces for the formation of nanoparticles.At the same time,ZCPS exhibited excellent stability of p H and ionic strength.2.Pickering emulsion was stabilized with ZCPs as particle stabilizers.The contact angle of ZCPs was 89.1~o when the mass ratio of zein to CMD was 2:1,which could stabilize Pickering emulsions.The particle size of emulsion drops decreaseed with the increase of particle concentration and increases with the increase of oil phase fraction.ZCPs stabilized Pickering emulsions at various particle concentrations and oil fractions were stable during long-term storage.The rheological measurements indicated that the viscosity and gel-like structure were relied on ZCPs concentrations and oil volume fractions.Confocal laser scanning microscope showed that ZCPs formed the densely layer around the oil droplets.ZCPs stabilized Pickering emulsions significantly inhibited lipid oxidation compared to zein nanoparticles stabilized emulsions.In vitro digestion study suggested that the bioaccessibility and stability of curcumin in ZCPs stabilized Pickering emulsions were higher than those in bulk oil and zein nanoparticles stabilized emulsions.3.The Pickering emulsion stabilized by zein/carboxymethyl dextrin nanoparticles was transformed into emulsion gel by carrageenan binding covalent cross-linking.The texture,WHC and freeze-thaw stability of the emulsion gels increased after crosslinking.The confocal laser scanning microscope and scanning electron microscopy suggested that droplet clusters could be observed in gel with higher concentration of emulsion.The rheological measurements indicated that the viscosity and gel-like structure of the emulsion gel were determined by crosslinking agent and emulsion concentration.The photothermal stability of curcumin was significantly enhanced after crosslinking.In vitro digestion study suggested that the bioaccessibility of curcumin in emulsion gel crosslinked was lower compared to emulsion gel without crosslinking agent.4.Pork back fat in sausages was replaced with emulsion gel containing curcumin.The effects of emulsion gel and curcumin on the properties of sausages were assessed.Emulsion gels increased L*and decreased a*of sausages.Curcumin increased b*of sausages.Emulsion gels and curcumin was no significant different in p H values of sausages.Emulsion gels improved hardness and viscoelasticity of sausages.Curcumin had no significant effect on the texture of sausage.After adding emulsion gels and curcumin,the cooking loss of sausages was significantly decreased and antioxidant activity was significantly increased.