Abstract: The invention concerns a process for preparing particles, which particles contain one or more spaces in which a gas phase is present which comprises at least one active ingredient, in particular at least one aroma, flavor or precursor for an aroma or flavor, and which space or spaces are at least substantially surrounded by an enveloping phase which at ambient temperature is at least substantially solid and at least substantially impermeable to the active ingredient, comprising allowing the gaseous active ingredient to migrate from or through the enveloping phase into the space or spaces at a temperature at which the enveloping phase is permeable to the gaseous active ingredient; and then cooling the particles to a temperature at which the enveloping phase of the particles is at least substantially impermeable to the active ingredient in the particles.