Process for the production of a packaged product, preferably of a packaged food product or of a packaged product to be used for cosmetics/phytocosmetics, characterized in that it comprises the sequence of the following phases: a) provide a product to be packaged; b) bringing said product to be packaged, which has been provided, at a temperature of 60-65°C; c) partially filling with said product, which is at a temperature of 60-65°C an envelope of flexible and expandable material: d) creating a vacuum inside said envelope; e) sealing said envelope after the previous vacuum creation phase; f) thermally treating the envelope thus obtained, and partially filled with said product, by successive sub-phases comprising: 1. a first heating sub-phase to bring the envelope to a temperature of about 80°- 95°C, 2. a second sub-phase of maintaining the envelope at the aforementioned temperature of about 80°- 95°C reached in the previous sub-phase, and 3. a third cooling sub-phase of the envelope to bring it to a temperature equal to or lower than about 14°C, said process being characterized in that, during the sub-phase f2) of said thermal treatment phase, the pressure externally exerted on said envelope, which is partially filled by said product, remains always lower than the pressure present inside the envelope, thus allowing said envelope to vary its internal volume during said thermal treatment phase, and being further characterized in that: - during the heating sub-phase f1), the pressure inside the envelope increases, passing from a first initial value, in which it substantially balances the pressure external to the envelope, to a second value that is greater than external pressure, - during the maintenance sub-phase f2) of the heating temperature, the pressure outside the envelope remains always lower than the pressure that is present inside it, during the rapid cooling sub-phase f3), the pressure inside the envelope varies and decreases, passing from said second value, which has been reached and maintained during the previous sub-phases, to a value in which substantially balances the external pressure, and - during the heating sub-phase f1), the envelope, partially filled and occupied with the food, increases its internal volume from an initial value to a second value which is greater than the initial one, and thus passes from an initial condition to a dilated/expanded condition, - during the maintenance sub-phase f2) of the heating temperature, the envelope, partially filled with the food, maintains the volume inside at said second value, which it is greater than the initial one, and thus maintains its achieved dilated/expanded condition, - during the rapid cooling sub-phase f3), the envelope, partially filled and occupied with the food, decreases its volume which passes from said second value to the initial value, thus passing from the dilated/expanded condition to the initial condition. a) provide a product to be packaged; b) bringing said product to be packaged, which has been provided, at a temperature of 60-65°C; c) partially filling with said product, which is at a temperature of 60-65°C an envelope of flexible and expandable material: d) creating a vacuum inside said envelope; e) sealing said envelope after the previous vacuum creation phase; f) thermally treating the envelope thus obtained, and partially filled with said product, by successive sub-phases comprising: 1. a first heating sub-phase to bring the envelope to a temperature of about 80°- 95°C, 2. a second sub-phase of maintaining the envelope at the aforementioned temperature of about 80°- 95°C reached in the previous sub-phase, and 3. a third cooling sub-phase of the envelope to bring it to a temperature equal to or lower than about 14°C, 1. a first heating sub-phase to bring the envelope to a temperature of about 80°- 95°C, 2. a second sub-phase of maintaining the envelope at the aforementioned temperature of about 80°- 95°C reached in the previous sub-phase, and 3. a third cooling sub-phase of the envelope to bring it to a temperature equal to or lower than about 14°C, - during the heating sub-phase f1), the pressure inside the envelope increases, passing from a first initial value, in which it substantially balances the pressure external to the envelope, to a second value that is greater than external pressure, - during the maintenance sub-phase f2) of the heating temperature, the pressure outside the envelope remains always lower than the pressure that is present inside it, - during the heating sub-phase f1), the envelope, partially filled and occupied with the food, increases its internal volume from an initial value to a second value which is greater than the initial one, and thus passes from an initial condition to a dilated/expanded condition, - during the maintenance sub-phase f2) of the heating temperature, the envelope, partially filled with the food, maintains the volume inside at said second value, which it is greater than the initial one, and thus maintains its achieved dilated/expanded condition, - during the rapid cooling sub-phase f3), the envelope, partially filled and occupied with the food, decreases its volume which passes from said second value to the initial value, thus passing from the dilated/expanded condition to the initial condition.