Hi Vincent, if when you say safe you mean inflammable, there are many refrigerant gases that are inflammable and that can be used for extraction purposes. Hydrofluorocarbons (HFCs) are used for this purpose but it's illegal to knowingly vent some of them into the atmosphere. It might be a good idea to contact the makers of Jungle Essence to find out which gas it is that they use. It may be R-134a, which is inert and doesn't harm the ozone layer. It's one of the more commonly used HFCs for extraction purposes. As you know, Butaflors are made with butane. Extracts made with HFCs are called Florasols. They actually call both the extracts and the HFCs themselves Florasols, infact.
To be honest, I'd forget about supercritical extraction if I were you. N-butane's critical point is 152 °C. You'd destroy the more heat sensitive aroma compounds at that temperature. Not only that but you'd need a heavy duty tank to withstand the pressure. I'd suggest that the makers of Jungle Essence are actually being a little dishonest. To my knowledge there aren't any liquid gases that have a critical point anywhere near room temperature and at "low pressure". Even R-134a has a critical point of 101 °C. The gases with critical points even close to room temperature, have vapor pressures far too high for them to be contained within the canister shown within the video. A heavy duty tank would be required to withstand the pressures involved.
That's not to say that a solvent in a closed system, under relatively low pressure wouldn't still extract more efficiently than if it were in an open vessel. It would but not as efficiently as if it were supercritical. Closed systems tend to be expensive and most people lack the engineering experience to safely make their own. A Thermos is a practical and affordable alternative for the amateur perfumer.
I haven't extracted from fruit before, so you'll have to try it for yourself. I'd recommend that you use a Thermos to begin with, before investing heaviliy in a closed system. If the fruit smells extremely bland after extraction (upon returning to ambient temperature and being freshly cut), then you know that it's been extracted thoroughly enough. I hope that this was helpful.
Edited by Pears - 9/15/13 at 4:46am