Over the past three decades, the twin-screw extrusion technology has played an important and decisive role in the innovation and development of flavors encapsulation. This continuous process can treat a wide variety of materials to develop aromatic compounds with high added value.
Flavors are expensive and sensitive products (volatile, sensitive to light, easily oxidized and reactive) used as additives in the food industry in particular. To maintain their integrity and stability as long as possible, aromatic molecules must be protected – they are said to be « encapsulated » – in an envelope that is being further dissolved under certain conditions (solvent, temperature, ..) and releases flavors in the destination medium.
What is flavor encapsulation?
Encapsulation or micro encapsulation of flavors consists in protecting a flavoring agent or a mixture of molecules with a dedicated envelope. Encapsulation can limit the degradation or loss of flavor during the various product processes and storage. The envelope can also provide functional properties, such as a controlled release of aromatic molecules in a given environment like water (if flavored tea), mouth (solid food: candy, toothpaste, ..) or spray .
The encapsulation of flavors via twin screw melt extrusion:
The remarkable properties of distributive and dispersive mixing of the twin screw extruder are used to encapsulate flavors continuously.
The matrix powder is first metered into the extruder and then conveyed and mixed by the screws. By use of viscous dissipation and controlled heating, the powder is melted and transformed into a viscous dough. Aromatics, usually in liquid form, are then accurately introduced into a barrel module during the process: the screw configuration is adjusted to disperse the small droplets of liquid flavors into the molten matrix and distribute them regularly throughout the mass. Temperature and screw shear should be controlled to secure the new homogeneous mixture at a specific and stable viscosity and avoid aggregation of the small droplets.
Clextral process expertise is specially developed for this application, on the technical aspect (control of extrusion parameters, construction of the machine and peripheral equipment, screw geometry and die …) as well as for process knowledge: residence time, flavors injection levels, raw materials…
Applications of encapsulated flavors
Extruded encapsulated flavors are used as ingredients in the food industry for applications such as rapid preparations for desserts, cakes and biscuits, tea bags, loose tea, coffee, instant drinks and confectionery. They are also used to incorporate active ingredients in tablets by direct compression or in cosmetic products for instance.
By extension, the encapsulation technique can be applied to many polymers, various compounds and oxidation-sensitive or heat-sensitive molecules and active substances (vitamins, drugs, bacteria) …
The advantages of twin-screw extrusion for encapsulating flavours
- Continuous and precise processing with reduced manufacturing costs without producing effluents
- A secured and easily installed compact processing unit
- A wide range of flavors and combinations of matrices
- Excellent dispersion in the protective matrix
- Ability to control the flavors dispersion parameters
- Highly-efficient protection, enabling long storage and shelf life (2 to 3 years)