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Food grade nano-capsules show formulation potential

By Nathan Gray , 25-Oct-2010
Last updated on 25-Oct-2010 at 13:37 GMT

Nano-capsules that can modulate the release of the incorporated substances may have applications in the formulation of functional foods, as well as relevance in food preservation and storage, according to new research.

The study new study, published in LWT - Food Science and Technology, suggests the optimal formulation for nano-capsules for the use in food formulation, using the emulsification diffusion method (EDM).

“It has been shown that the EDM is an excellent option to prepare nano-capsules from food ingredients with the potential implications that this system can have in food technology due to its capsular structure,” wrote the resarchers, led by Dr. M. Zambrano-Zaragoza from the Universidad Nacional Autónoma de México.

They added that for food technologies, nano-capsules show an advantage over other nano-particulate systems as they have an oil core that can exhibit a polyfunctional behaviour.

New possibilities

Nanotechnology has opened a host of new possibilities in the field of food formulation, preservation, and storage. In particular, the structure of nano-capsules makes them particularly appealing for food development.

In food technology, a nano-capsule envelope can serve as a protective barrier, that may preserve the functionality and bioavailability of food additives, or act as “an insulating membrane to prevent incompatibilities”, noted the researchers.

They added that, currently, nanotechnology research in food has focused on the development of new packaging materials, nutraceuticals, and antimicrobial agents, with very little focus on the improved formulation, preservation and storage of foods.

The oily core of nano-capsules can be an active oil or can serve as a vehicle to contain different substances, particularly food additives and dietary supplements such as flavours, probiotics, sweeteners, nutraceuticals, pigments, antimicrobials, antioxidants, or any other materials requiring encapsulation, stated the authors.

According to the authors, the emulsification diffusion method (EDM), developed for the encapsulation of drugs, may be attractive to design and produce nano-capsules with potential food applications.

The new research evaluated the potential use of the EDM to prepare nano-particles from acceptable food-grade materials, focusing on the optimal to produce food-grade nano-capsules for the potential use in food formulation.

Nano- production

The optimal conditions for the production of nano-capsules were at a sheer rate of 10,917 s-1, with 0.5 grams per litre of polyvinyl alcohol and 256 mg of poly-e-caprolactone. This gave a predicted particle size 250 nm, with a density of 021 grams per cm3, a polydispersion index of 0.045, and zeta potential of -20.02.

Particle size increased with a decrease of shear rate and an increase of polyvinyl alcohol concentration above 0.5g/L, with a maximum particle size of 1880 nm produced at a sheer rate of 138 s-1 and 0.9 g/L of polyvinyl alcohol.

“Formation of nano-capsules with DL-a-tocopheryl acetate and β- carotene confirmed the versatility and reproducibility of the EDM when batches with different materials are prepared under optimal conditions,” stated the authors.

Future formulation

“We think that the EDM is a good option to prepare harmless and safe food nanosystems in particular biodegradable nano-capsules,” wrote the researchers.

They added that keeping the same preparation conditions, the formation of nano-capsules is also possible from other food oily materials with similar characteristics.

Source: LWT - Food Science and Technology

Published online ahead of print, doi: 10.1016/j.lwt.2010.10.004

“Optimization of Nanocapsules Preparation by the Emulsion-Diffusion Method for Food Applications”

Authors: M.L. Zambrano-Zaragoza, E. Mercado-Silva, E. Gutiérrez-Cortez, E. Castaño-Tostado, D. Quintanar-Guerrero

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