Alexander Navarrete

Encapsulation and Co-Precipitation Processes with Supercritical Fluids: Applications with Essential Oils

Essential oils have important commercial applications as preservatives and flavours, and more recently as natu- ral antimicrobial agents. These applications require a suitable formulation constituted by biodegradable compounds that protect the essential oil from degradation and evaporation at the same time that allows for a sustained release. Microcap- sules of biopolymers loaded with essential oils meet these requirements. Such microcapsules can be prepared with differ- ent processes such as spray-drying, freeze-drying and coacervation, and supercritical fluids are an advantageous medium for this purpose. Some supercritical fluid-based precipitation processes have already been applied to produce these micro- capsules. Amongst them, the results obtained with Particles from Gas Saturated Solutions (PGSS), PGSS-drying and Con- centrated Powder Form (CPF) processes are particularly promising. Recent developments in the preparation of formula- tions with supercritical fluids include the preparation of liposomes and micelles, which can be suitable carriers for essen- tial oils.

CHAPTER 8:Post‐extraction Processes: Improvement of Functional Characteristics of Extracts

The biological activity of natural extracts is not determined only by their chemical composition. Other parameters, such as the physical parameters of the product (particle size and morphology, crystalline/amorphous structure) as well as the combination of the active extract with carriers or co‐active materials, also play a major role. With this perspective, post‐extraction and formulation methods are described in this chapter. Elimination of residual solvents and other contaminants as required by the regulations for commercialization is discussed first. Particle reduction techniques are presented next, which are essential both for obtaining a desired product size and morphology, as well as for increasing the bioavailability of active compounds with limited solubility in water. Formulation processes, which are used to protect sensitive active compounds, or for providing additional functionalities to the product, are also presented. Finally, the formulation of a β‐carotene extract for application as a natural colorant in foods and beverages is presented as a case study. The techniques discussed include top‐down milling and homogenization processes, and bottom‐up crystallization, emulsion‐template, spray‐drying and supercritical fluid processes, for the production of micro‐ or nanoparticles, microcapsules or microcomposites, as well as multifunctional nanocarriers such as micelles or liposomes.