Farbication Of Zein Colloid Particles And Their Applications

Zein, the main corn protein, contains over50%hydrophobic amino acids. Zein is notsoluble in water, and its usage in food industry was usually limited. Zein contains sharplydefined hydrophobic and hydrophilic domains at its surface, and is capable of self-assemblyto form a wide variety of mesostructures. Therefore, zein is a good candidate for fabricatingnaturally renewable films and/or colloidal particles as vehivles for actives, edible films aswell as Pickering emulsifier in view of due to its biocompatibility, biodegradability andmucoadhesive ability. The objective of this work was to modify zein colloids particles via theinteraction of zein and chitosan, to explore their possible application in nutrition delivery,Pickering emulsifier, and edible films. The main results are as following：Fabrication and characterization of zein/SBP complex particles. We prepared zein/SBPcomplex particles with particle sizes300–400nm via a simple antisolvent procedure. Storagestability, and loading capacity and delivery for curcumin, as well as in vitro gastrointestinaldigestion of zein/SBP colloid particles were extensively evaluated. Zein/SBP complexparticles were stable at high salt and various pH ranges from2.0to10.0. These complexparticles possessed strong loading capacity (above50%) and high encapsulation efficiency(above90%) for curcumin. Meanwhile, zein/SBP complex particles had strong anti-digestionin in vitro gastrointestinal tract, and can be used for colon-specific drug delivery. This kind ofcolloid particles facilitated to the design of functional food formulation.Fabrication and characterization of Pickering emulsions stabilized by Zein/CH complexparticles. The effects of the ratios of zein/CH, pH values and ion strength on Pickeringemulsion formation and physical stability were carefully explored. The interaction betweenzein and chitosan induced the flocculation of zein colloid particles, the three-phase contactangles of zein complex particles were close to90owhen the zein/CH ratios were10:1and20:1. These complex particles can be used as particle emulsifier to fabricate super-stablePickering emulsions over9month storages. The possible formation pathway can be attributedto the CH-induced ridge flocculation of zein colloid particles at the oil/water interface and theformation of multi-layer framework of zein colloid particles at the oil/water interface. Thiskind of interface fabric contributed to the high resistance of the formed Pickering emulsions to coalescence and Oswald ripening.Fabrication of curcumin-loaded zein/CH complex particles with double functions,Pickering emulsions were fabricated via corn oil and alga oil as oil phase. Microstructure,storage and oxidant stability of Pickering emulsion were extensively investigated. Curcuminloading did not change the wettability of zein/CH complex particles, which were also suitableto produce stable Pickering emulsions. Primary (lipid hydroperoxides) and secondary oxidantproducts (malondialdehyde, MDA) of Pickering emulsions after thermally acceleratedoxidation were monitored, and hexanal was measured using GC-MS techniques. Pickeringemulsion stabilized by curcumin-loaded zein/CH complex particles present super antioxidantcapacity, the primary products was significantly lower than the antioxidant emulsions viatargeted accumulation of resveratrol via during the complete stevioside micelles stabilized bycompetitive absorption of soy protein isolate (SPI) and stevioside (STE). CLSM indicatedthat the absorption and accumulation of zein/CH complex particles at the oil/water interface,and targeted accumulation of cucurmin at the interfaces was achieved via Pickeringemulsifier (zein/CH complex particles).Novel zein-sodium caseinate nanoparticles-stabilized emulsion films were fabricated viamicrofluidic emulsification (ZPE films), or in combination with solvent (ethyl acetate)evaporation techniques (ZPE-EA films). Some physical properties, including tensile andoptical properties, water vapor permeability (WVP) as well as microstructure of ZP-stabilizedemulsion films were evaluated and compared with SC emulsion (SCE) films. ZP-andSC-stabilized emulsion films exhibited a completely different microstructure, nanoscalar lipiddroplets were homogeneously distributed in ZPE film matrix and interpenetrating protein-oilcomplex networks occurred within ZPE-EA films, whereas SCE films presented aheterogeneous microstructure. The different stabilization mechanisms against creaming orcoalescence during the film formation accounted for the preceding discrepancy of themicrostructures between ZP-and SC-stabilized emulsion films. Interestingly, ZP-stabilizedemulsion films exhibited a better water barrier efficiency, the WVP values were only4050%of SCE films. The structural characteristics gave ZPE and ZPE-EA films improvedwater barrier capability, moderate mechanical resistance and extensibility, and hightransparency.