Preparation And Characterization Of Prolamin-based Coated Composite Particles For The Encapsulation And Delivery Of Resveratrol

Food proteins have been widely used as carrier materials for the encapsulation of bioactive ingredients because they are biodegradable,possess high encapsulation and loading capabilities.Prolamins are storage proteins found in endosperm of corn(zein),sorghum(kafirin),wheat(gliadin)and barley(hordein).Prolamins are structured to nanoparticle by facile antisolvent precipitation technique and the nanoparticles are widely used for the encapsulation of hydrophobic bioactives.The stability of prolamin nanoparticles is a matter of concern because of sensitivity of proteins to salts,pH,environment polarity and enzymes.Composite prolamin particles are developed to address the stability issues by coating prolamin particles with polysaccharides and proteins.The composite prolamin particles were used to improve the chemical stability,increase bioavailability and contribute to controlled release of encapsulated bioactive.Part 1:Kafirin nanoparticles in the absence and presence of beta-lactoglobulin(β-Lg)or casein were prepared and characterized in term of turbidity,size,ζ-potential.The particles stabilized by 2%β-Lg or 0.2%casein had the smallest size i.e.144 and 156 nm respectively and used for the encapsulation resveratrol.Encapsulation efficiency of resveratrol was between 67%and 76%in kafirin/milk protein particles and the highest in kafirin/casein particles.Loading capacity of resveratrol was lowest in kafirin/β-Lg followed by kafirin/casein and kafirin particles.Encapsulation in kafirin/milk protein particles improved total DPPH· scavenging capacity whereas screened out interaction of ABTS·+radical with resveratrol.Ultraviolet light stability of resveratrol ranked in order kafirin/casein>kafirin/[-Lg～kafirin.These results suggest that β-Lg-or casein-stabilized kafirin nanoparticles are promising systems for the encapsulation and protection of bioactive ingredients.Part 2:The aim of this study was to evaluate the effect of alginate/chitosan complex coating on the delivery of resveratrol encapsulated in zein particles.Resveratrol-loaded zein(RZ)particles had a particle size of～72 nm,ζ-potential of +15.01 mV and encapsulation efficiency>70%.RZ particles were coated with alginate/chitosan(Alg/Chi)complex layer at various polysaccharide concentrations.RZ-Alg/Chi spherical particles had the smallest size of 160.9 nm and ζ-potential of+43.01 mV at the concentration of either polysaccharide being 0.02%.FTIR and XRD results confirmed a change in the physical state of resveratrol and formation of the alginate/chitosan complexes.The Alg/Chi coating did not affect encapsulation efficiency of resveratrol but did improve the photostability,sustained release and bioaccessibility of resveratrol.Therefore,zein-alginate/chitosan particles could be the potential delivery system for polyphenols.Part 3:Hollow zein(HZ)and hollow zein-chitosan(HZ-CH)particles were prepared by using sodium carbonate(Na2CO3)as a sacrificial template.Particle size,PDI and ζ-potential of HZ particles were 65.57 nm,0.179 and-25.96 mV,respectively.Hollow zein-chitosan(HZ-CH)particles were assembled by coating HZ particle with 0.01-0.05%chitosan.The HZ-CH particles were positively charged and bigger in size as compared to HZ particles.Resveratrol as a model polyphenol was encapsulated in HZ-CH particles with an encapsulation efficiency and loading capacity of 91.29 and 14.49%correspondingly.Resveratrol-loaded hollow zein(RHZ)and hollow zein-chitosan(RHZ-CH)particles were bigger in size than the corresponding blank particles.Fluorescence results revealed the presence of resveratrol in hydrophobic zein shell.IR and XRD data showed that resveratrol transferred to an amorphous state in particles.The particles became smooth and less aggregated upon coating with chitosan.RHZ-CH particles showed better physical stability and protection of resveratrol at ambient and elevated temperatures as compare to RHZ during storage.DPPH· scavenging capacity of resveratrol was improved after encapsulation,but a reduction in ABTS scavenging was observed.A sustained release of resveratrol was found in RHZ-CH particles as compared to control and RHZ samples.Therefore,RHZ-CH particles could be used an efficient resveratrol delivery system for its application in functional foods.