Microencapsulation of phenolic extracts in calcium alginate beads for nutraceutical applications
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abstract
Bioactive ingredients are generally prone to degradation, both during storage and food processing, as
many of them are physically, chemically and/or enzymatically instable leading to their degradation or
transformation with the consequent loss of bioactivity. To overcome these limitations
microencapsulation emerges as a reliable response to protect and stabilize bioactives (or extracts
containing them), also offering the possibility of a controlled or targeted delivery [1].
The encapsulation materials, productive process, microcapsule’s morphology and ultimate application
conditions are the most important factors to be taken into account when des igning a novel
microencapsulated product, together with stability and functional properties issues. Moreover, to obtain
a successful product, the achievement of high encapsulation yields, process and release profile
reproducibility and overcome microcapsule’s aggregation, should be guaranteed.
For food applications the used materials must be considered “generally recognized as safe” (GRAS )
and be, preferably, biodegradable. Both EU through the EFSA and the US through FDA have many
strict rules about material usage for food applications. In this context, the most commonly used materials
are natural or natural-derived polymers. Among them, carbohydrate polymers (e.g. starch and cellulose
and their derivatives), plant exudates and extracts (e.g. gum, galactomannans, pectins and soybean
polysaccharides), marine extracts (e.g. carrageenan and alginate), microbial and animal derived
polysaccharides (e.g. xanthan, gellan, dextran and chitosan) and proteins were tested for these
purposes. In what concerns microencapsulation processes, a set of techniques are available (e.g.,
coacervation, extrusion, emulsion based process, liposomes etc.). Nevertheless, spray -based
processes are the most commonly used by academia and industry. They present the advantages of
being flexible and economically competitive, allowing a continuous production [2].
In this work the use of microencapsulation to protect natural extracts will be demonstrated with a case
study comprising the development of a nutraceutical formulation based on gelatine incorporating
alginate microspheres enriched with bioactive phenolic extracts obtained from wild Fragaria vesca L.
