Scientists expand encapsulation methods for bioactives

By Stephen Daniells

- Last updated on GMT

Related tags: Nutrition

Canadian scientists have developed a new encapsulation method using
chitosan and alginate to stabilize micronutrients and protect them
during passage through the stomach.

Under extreme conditions the stability of vitamin C, beta-carotene and the iron compound, ferrous fumarate, was greatly increased by encapsulation in the new functionalized beads, report the researchers in the Journal of Agricultural and Food Chemistry​. "This study demonstrated that encapsulation had an excellent capacity to protect bioactive molecules against temperature, humidity, and acidic conditions and allowed a controlled release of these compounds during gastrointestinal transit,"​ wrote the researchers, led by Monique Lacroix from the Institut National de la Recherche Scientifique (Institut Armand-Frappier) in Laval, Canada. "Therefore, the potential use of this new encapsulation method could be further explored and could be of great interest for cosmetic, pharmaceutical, and food uses." ​ Microcapsules are tiny particles that contain an active agent or core material surrounded by a shell or coating, and are now increasingly being used in food ingredients preparation. The technology can be used to deliver a host of ingredients - flavours, oils, peptides, amino acids, enzymes, acidulants, colours and sweeteners - in a range of food formulations, from functional foods to ice cream. As such, encapsulation of sensitive ingredients has become one of the most important and innovative applications in the food industry. "An ideal encapsulation system for micronutrients is to reduce the reactivity of the micronutrient in relation to the outside environment: it would have a maximal stability in acidic pH and resist extreme moisture conditions,"​ explained the researchers. New development ​ Alginate and chitosan are already employed for encapsulation since they can form gels in the presence of mineral ions like calcium, state the researchers in background information in the article. "Nevertheless, gel erosion is an important problem of alginate beads because it accelerates the release of the encapsulated substance,"​ they added. Lacroix and co-workers successfully developed the new encapsulation matrix consisting of alginate and chitosan by functionalising the non-toxic, biodegradable, and biocompatible polymers by a chemical reaction - acylation - with palmitoyl chloride. The functionalised beads were compared with normal alginate-chitosan beads. Acylation of the polymers led to the formation of palmitoylated alginate in the core of the beads and palmitoylated chitosan on the external layer. This increased the elasticity and water impermeability of the beads. In order to test the applicability of the new encapsulation method, the researchers conducted a release study in a solution that resembled gastrointestinal conditions. The functionalised encapsulated beads were "not susceptible to enzymatic and acidic attacks during transit in the stomach,"​ they stated. Moreover, a controlled release of the micronutrients was observed for the functionalised beads with slower release between 30 min and two hours, compared to the normal beads, and faster release between two and four hours. Source: Journal of Agricultural and Food Chemistry​ Published online ahead of print, ASAP Article, doi: "Alginate and Chitosan Functionalization for Micronutrient Encapsulation" ​Authors: J. Han, A.-S. Guenier, S. Salmieri, M. Lacroix

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