Study On Casein And Zein-based Carriers For The Co-encapsulation Of Bioactive Components

It has been reported that a combination of multiple bioactive components may produce an effect greater than the sum of individual effects.Moreover,there appear to be interesting market opportunities for functional foods fortified with a range of bioactive components.However,bioactive components with different solubility cannot be incorporated into food systems directly.Meanwhile,many bioactive components exist some limitations in oral-delivery applications,because they are sensitive to environmental factors,such as light,oxygen,and heat,and prone to oxidation and degradation during the processing,storage,and digestion.The design and development of edible carriers that could encapsulate multiple components is a useful method to overcome these limitations.Carriers with sophisticated structures,such as water-in-oil-in-water emulsions,biopolymer-based vesicles,have been widely used in the co-encapsulation of bioactive components with different solubility.However,these sophisticated carriers are limited in the food industry due to complicated preparation and physical instability.Although the simple structure carriers possess some advantages including high physical stability and simple preparation conditions,there are only a few studies available for the co-encapsulation of multiple bioactive components in carriers with the sample structure.In this study,food proteins were used as encapsulation materials to fabricate the O/W emulsions?lipid-based delivery system?and nanoparticles?lipid-free delivery system?by combining multiple properties of protein and selecting suitable preparation methods.The possibility of co-encapsulating multiple bioactive components with different solubility in the simple structure carriers was investigated.The location,partition,chemical stability,biological activities,and controlled release properties of co-encapsulated bioactive components were investigated.1.Co-encapsulation of trans-and cis-resveratrol using?-casein complexes and micelles.?-Casein can bind and encapsulate small-molecular-weight bioactive components by the formation of molecular complexes and micelles.The possibility of co-encapsulating trans-and cis-resveratrol in molecular complexes and micelles,and the protective effect of co-encapsulation on both isomers were evaluated.?-Casein could bind trans-and cis-resveratrol simultaneously to form protein-diligand complexes,which was independent of the sequence of two isomers addition.?-Casein could self-assemble into micelles at above its concentration of 20?M and pH 7.0,which could encapsulate both trans-and cis-resveratrol.The encapsulation efficiency of both isomers increased as the protein concentration increased.The maximum encapsulation efficiency of trans-and cis-resveratrol was 69%and 57%,respectively.The formation of?-casein-resveratrol complexes did not change the microenvironment of both isomers.The microenvironment of both isomers changed from the hydrophilic environment to the hydrophobic environment when the polyphenols were encapsulated into the micelles.The?-casein-resveratrol complex did not affect the isomerization of trans-resveratrol to cis-resveratrol,while?-casein micelles could delay the photo-isomerization of trans-isomer to cis-isomer.Both?-casein-ligand complexes and micelles could provide a protective effect on trans-and cis-resveratrol against degradation,but?-casein-ligand complexes showed a better protective effect on both isomers than did?-casein micelles in long-term storage.2.Co-encapsulation of?-tocopherol and resveratrol using O/W emulsions stabilized by sodium caseinate.Base on the ligand-binding and self-assembling properties,sodium caseinate-resveratrol complex particles were fabricated.The O/W emulsions stabilized by sodium caseinate-resveratrol complex particles were obtained by using high-pressure homogenization,which was used to co-encapsulate?-tocopherol and resveratrol.The impact of gum Arabic and pectin on the co-encapsulation,location,partition,protection,and behavior in the gastrointestinal tract was evaluated.Sodium caseinate-stabilized emulsions had a bimodal size distribution.The size and?-potential of emulsified droplets were 643 nm and-36 mV,respectively.?-Tocopherol was encapsulated in the inner oil phase of emulsions with an encapsulation efficiency of 92.4%.The total encapsulation efficiency of resveratrol within emulsions was 65%.The encapsulation efficiency of resveratrol in the surface layer of emulsified droplets and the aqueous phase was 44.4%and 20.6%,respectively.The surface protein percentage and concentration,and encapsulation efficiency of resveratrol increased as the concentration of gum Arabic or pectin increased.When the concentration of pectin was1.0%,the encapsulation efficiency of resveratrol reached the maximum value of 91.8%.Co-encapsulation could improve the chemical stability of?-tocopherol during storage anddigestion,and the addition of gum Arabic or pectin could further enhance the storage stability of?-tocopherol and resveratrol.The addition of gum Arabic?0.1%?1.0%?and pectin?0.1%?could improve the bioaccessibility of?-tocopherol and resveratrol.However,pectin at the concentration of 0.5%?1.0%decreased the bioaccessibility of both bioactive components significantly.3.Co-encapsulation of?-tocopherol and resveratrol using zein nanoparticles.To investigate the possibility of co-encapsulating multiple bioactive components with different solubility,zein nanoparticles prepared by the anti-solvent method were used to co-encapsulate?-tocopherol and resveratrol.Zein nanoparticles had a size of 80 nm with a narrow size distribution.The encapsulation efficiency of?-tocopherol and resveratrol was 99%and 67%,respectively.?-Tocopherol was located in the inner core of zein nanoparticles with a hydrophobic environment,and resveratrol was located between the hydrophobic core and surface of zein nanoparticles with a less hydrophobic environment.The co-encapsulation could shield the antioxidant activity of?-tocopherol and resveratrol.Co-encapsulation of?-tocopherol and resveratrol within zein nanoparticles could provide a protective effect on the bioactive components and eliminate the negative effect of?-tocopherol on the chemical stability of resveratrol.4.Co-encapsulation of peppermint oil and resveratrol using O/W emulsions stabilized by zein-pectin complex particlesTo further investigate the possibility of co-encapsulating bioactive components with different solubility,based on the above results,resveratrol-loaded zein-pectin complex particles prepared by using the anti-solvent method were used to stabilize the O/W emulsions,which was used to co-encapsulate peppermint oil and resveratrol.Size and?-potential of zein-pectin particles varied from 140 nm to 240 nm and-27 mV to-35 mV,respectively.The three-phase contact angle of zein-pectin nanoparticles varied from 63°to 78°.The encapsulation efficiency of resveratrol in zein-pectin nanoparticles ranged from 72%to 76%.Peppermint oil emulsions stabilized by zein-pectin particles had a size of 529 nm to 709 nm and?-potential of around-40 mV.The addition of pectin could improve the physical stability of peppermint oil emulsions during the storage.The encapsulation efficiency of peppermint oil and resveratrol was 88%and 99%,respectively.The encapsulation efficiency of resveratrol in the aqueous phase and emulsified droplets varied from 18%to 33%and 66%to82%,respectively.As the concentration of pectin increased,the competitive adsorption between free pectin molecules and zein-pectin nanoparticles was observed,resulting in the formation of a mixed surface layer.This could also change the partition of resveratrol in emulsions.A combination of peppermint oil and resveratrol showed synergistic antibacterial effects.Co-encapsulation of peppermint oil and resveratrol could enhance their antibacterial activity.Increasing the pectin concentration could improve the chemical stability of resveratrol and peppermint oil and prolong the antimicrobial efficiency of emulsions during storage.5.Co-encapsulation of curcumin and catalase using zein-chitosan complex nanoparticles.Protein-based nanoparticles have some limitations in the colon-specific delivery,such as the instability in the gastrointestinal environment and the fast release of bioactive components.To overcome these limitations,chitosan-sodium tripolyphosphate?CS-TPP?nanoparticles were prepared to co-encapsulate curcumin?CUR?and catalase?CAT?.Then,zein-chitosan?ZC?nanoparticles were prepared by co-axial electrospraying using CS-TPP nanoparticles as the core and zein solutions as the shell layer.The mean size,PDI,and?-potential of CUR-CAT-co-loaded CS-TPP nanoparticles were 235 nm,0.291,and+17 mV,respectively.The ZC complex nanoparticles showed a narrow size distribution with around 250 nm.The ZC nanoparticles could internalize into Caco-2 cells via macropinocytosis and clathrin-mediated endocytosis,and significantly increase the uptake efficiency of CUR and CAT with 15.2%and 17.5%,respectively.CUR-CAT-co-loaded ZC nanoparticles could protect Caco-2 cells against H₂O₂-induced oxidative damage via significantly decreasing intracellular ROS generation.The initial burst release was not observed in simulated gastro-intestinal fluids.The cumulative release of CUR and CAT was 36%and 25%in simulated gastro-intestinal fluids,respectively.Both CUR and CAT showed a sustained-release profile in simulated colon fluids.The final cumulative release percentage of CUR and CAT was above 90%.