A comprehensive review on the controlled release of encapsulated food ingredients; fundamental concepts to design and applications

Poly(D,L-lactic-co-glycolic acid) (PLGA) is the most frequently used biodegradable polymer in the controlled release of encapsulated drugs. Understanding the release mechanisms, as well as which factors that affect drug release, is important in order to be able to modify drug release. Drug release from PLGA-based drug delivery systems is however complex. This review focuses on release mechanisms, and provides a survey and analysis of the processes determining the release rate, which may be helpful in elucidating this complex picture. The term release mechanism and the various techniques that have been used to study release mechanisms are discussed. The physico-chemical processes that influence the rate of drug release and the various mechanisms of drug release that have been reported in the literature are analyzed in this review, and practical examples are given. The complexity of drug release from PLGA-based drug delivery systems can make the generalization of results and predictions of drug release difficult. However, this complexity also provides many possible ways of solving problems and modifying drug release. Basic, generally applicable and mechanistic research provides pieces of the puzzle, which is useful in the development of controlled-release pharmaceuticals. Copyright © 2011 Elsevier B.V. All rights reserved.

The fabrication of carvacrol-loaded chitosan nanoparticles was achieved by a two-step method, i.e., oil-in-water emulsion and ionic gelation of chitosan with pentasodium tripolyphosphate. The obtained particles possessed encapsulation efficiency (EE) and loading capacity (LC) in the ranges of 14-31% and 3-21%, respectively, when the initial carvacrol content was 0.25-1.25 g/g of chitosan. The individual particles exhibited a spherical shape with an average diameter of 40-80 nm, and a positively charged surface with a zeta potential value of 25-29 mV. The increment of initial carvacrol content caused a reduction of surface charge. Carvacrol-loaded chitosan nanoparticles showed antimicrobial activity against Staphylococcus aureus, Bacillus cereus and Escherichia coli with an MIC of 0.257 mg/mL. The release of carvacrol from chitosan nanoparticles reached plateau level on day 30, with release amounts of 53% in acetate buffer solution with pH of 3, and 23% and 33% in phosphate buffer solutions with pH of 7 and 11, respectively. The release mechanism followed a Fickian behavior. The release rate was superior in an acidic medium to either alkaline or neutral media, respectively.

There is a need for edible delivery systems to encapsulate, protect and release bioactive and functional lipophilic constituents within the food and pharmaceutical industries. These delivery systems could be used for a number of purposes: controlling lipid bioavailability; targeting the delivery of bioactive components within the gastrointestinal tract; and designing food matrices that delay lipid digestion and induce satiety. Emulsion technology is particularly suited for the design and fabrication of delivery systems for lipids. In this article we provide an overview of a number of emulsion-based technologies that can be used as edible delivery systems by the food and other industries, including conventional emulsions, nanoemulsions, multilayer emulsions, solid lipid particles, and filled hydrogel particles. Each of these delivery systems can be produced from food-grade (GRAS) ingredients (e.g., lipids, proteins, polysaccharides, surfactants, and minerals) using relatively simple processing operations (e.g., mixing, homogenizing, and thermal processing). The structure, preparation, and utilization of each type of delivery system for controlling lipid digestion are discussed. This knowledge can be used to select the most appropriate emulsion-based delivery system for specific applications, such as encapsulation, controlled digestion, and targeted release.