Release of nano-encapsulated flavour compounds in designed food gels

In spite of the advances in flavour research, the prediction and control of flavour performance in complex food systems is still limited. In recent years, an aspect is receiving a growing attention: the structural organization of the food matrices in relation to flavour binding, release and flavour perception. The perception of the release of a lipophilic aroma compound widely used in food and non-food fields, R-(+)-limonene, was evaluated in this work by means of an electronic nose when using agar gel as encapsulating medium. Stability in encapsulation is reached if the aroma does not show a tendency to migrate from a phase to the other. Encapsulation and/or nano-encapsulation are successful solution to the problem. To that purpose, in this work cyclodextrins (CD) were used as emulsion stabilizers: CD were enclosed in the system where they act as the shell material protecting limonene. The expected functional properties were achieived due to cyclodextrins hydrophobic nano-cavity and hydrophilic external surface. CD-flavour complexes were included in the gel phase. Agar gels were produced at different concentrations ranging from 0.2 to 1% (w/v). Mechanical and rheological properties of the soft materials were evaluated. The perception of the flavour release from the agar/limonene systems was quantified by means of the electronic nose: the results of tweak evaluations are here presented. The cyclodextrin/limonene complexation was carried out according to the paste method. Few preliminary results of the analytical gas-cromatographic head space analysis of the CD-mediated aroma release are finally presented, showing the considerable effect of the cyclodextrins as emulsifying agents.