James D. Oxley

Engineered Nanoscale Food Ingredients: Evaluation of Current Knowledge on Material Characteristics Relevant to Uptake from the Gastrointestinal Tract

The NanoRelease Food Additive project developed a catalog to identify potential engineered nanomaterials (ENMs) used as ingredients, using various food-related databases. To avoid ongoing debate on defining the term nanomaterial, NanoRelease did not use any specific definition other than the ingredient is not naturally part of the food chain, and its dimensions are measured in the nanoscale. Potential nanomaterials were categorized based on physical similarity; analysis indicated that the range of ENMs declared as being in the food chain was limited. Much of the catalogs information was obtained from product labeling, likely resulting in both underreporting (inconsistent or absent requirements for labeling) and/or overreporting (inability to validate entries, or the term nano was used, although no ENM material was present). Three categories of ingredients were identified: emulsions, dispersions, and their water-soluble powdered preparations (including lipid-based structures); solid encapsulates (solid structures containing an active material); and metallic or other inorganic particles. Although much is known regarding the physical/chemical properties for these ingredient categories, it is critical to understand whether these properties undergo changes following their interaction with food matrices during preparation and storage. It is also important to determine whether free ENMs are likely to be present within the gastrointestinal tract and whether uptake of ENMs may occur in their nanoform physical state. A practical decision-making scheme was developed to help manage testing requirements.

Overview of Microencapsulation Process Technologies

Over two dozen processes exist for the preparation of microcapsules. Common processes include atomization, spray coating, coextrusion, and emulsion-based systems. Examples of these four categories include spray drying, fluid-bed coating, vibrating nozzle coextrusion, and complex coacervation. These processes cover a wide range of particle sizes, payloads, morphologies, production capacities, cost, and materials. Collectively, the technologies enable the production of capsules from tens of nanometers to millimeters in diameter with payloads up to 99%. Microsphere matrix particles or core–shell microcapsules can be commercially produced at capacities of several tons per hour to encapsulate solids and liquids with a variety of shell materials. Proper process selection is dependent on the specific parameters of a designed microcapsule.