Author : Yuanjie Pan
Release : 2015
Genre :
Kind : eBook
Book Rating : 485/5 ( reviews)
Book Synopsis Encapsulation Systems for Enhanced Oxidative Stability and Controlled Release of Encapsulants by : Yuanjie Pan
Download or read book Encapsulation Systems for Enhanced Oxidative Stability and Controlled Release of Encapsulants written by Yuanjie Pan. This book was released on 2015. Available in PDF, EPUB and Kindle. Book excerpt: Ability of encapsulation systems to improve oxidative stability of the encapsulated bioactives and control the release of these compounds during digestion is critical for shelf-life of products and enhanced bioavailability of the encapsulated bioactives. The objectives of this study were to evaluate: (a) the effect of chemical and physical properties of the core and interface of encapsulation systems in influencing the oxidative stability of the encapsulated compounds, and (b) the influence of interfacial composition on dynamics of the interface during simulated intestinal digestion and the correlation of structural changes in interface with the release of free fatty acids. In this research, design of the interface of the encapsulation systems to improve the oxidative barrier properties includes engineering chemical and physical properties of the interface. Oil-in-water emulsion was selected as a model encapsulation system for encapsulating hydrophobic bioactive compounds. Chemical properties of the interface were engineered using localization of antioxidants at the interface by selecting emulsifiers with antioxidant properties and chemical conjugation of antioxidants to the interfacial layer. Physical properties of the interface were modified using a layer-by-layer coating approach at the emulsion interface. To evaluate the influence of core properties of the encapsulation systems in influencing oxidative stability of bioactives, encapsulation systems were designed using both lipid and protein cores. In the case of lipid core encapsulation systems, oil-in-water emulsion, solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs) were evaluated. In the case of protein core particles, zein protein core particles were synthesized and the oxidative barrier properties of these particles were compared with emulsions. Oxidative barrier properties of the encapsulation systems were simulated by measuring the rate of reaction of peroxyl radicals generated in the aqueous phase with the encapsulated radical sensitive dye in the core. The results of peroxyl radical permeation were compared to the stability of encapsulated model bioactives in encapsulation systems. Structure changes of the interface of encapsulation systems during simulated intestinal digestion were measured using a Fluorescence Resonance Energy Transfer (FRET) based real-time method and these changes were correlated with the release of free fatty acids. Role of biopolymer coatings at the interface in influencing the structure changes of interface during intestinal digestion was evaluated. The results of this research demonstrate the advantage of localization of antioxidant at the interface using emulsifiers with antioxidant properties and localizing a model antioxidant at the interface by chemical conjugation of the antioxidant to the interfacial layer in reducing permeation of radicals and oxidation of a model encapsulated bioactive. However, short chain polymer coatings at the interface of encapsulation systems had limited impact on improving the oxidative stability of the model encapsulated bioactive. Zein colloidal particles had improved oxidative stability against radical induced oxidation compared to oil-in-water emulsions. Neither zein colloidal particles nor oil-in-water emulsions were capable of limiting oxygen induced oxidation. By comparing the oxidative stability of encapsulated bioactives in SLNs and NLCs, the results suggest that the intra-particle distribution of the encapsulated bioactive affected their oxidative stability. Oxidative stability of the encapsulated bioactive improved as the proportion of liquid lipid within particles increased in NLCs. FRET method was effective in measuring the real-time changes in the interface during digestion without separation the encapsulation systems. Results from the FRET measurements were correlated to the release of free fatty acids. The results demonstrate that the disruption of phospholipids at the interface and the displacement from the interface was instantaneous upon addition of bile salts. Moreover, addition of a second layer of polymers at the interface could decrease the extent of interface disruption by bile salts and pancreatic lipase and the release of free fatty acids during intestinal digestion. Overall, the results of this research provide a quantitative framework to engineer the interface and core of encapsulation systems and evaluate their oxidative barrier properties and also enable detailed understanding of real-time dynamics of interface of encapsulation systems during simulated intestinal digestion. This comprehensive approach can enable rational design and engineering of encapsulation systems for extended oxidative stability and controlled release of encapsulated bioactives.
