The present invention relates to a method of dehydrating pieces of intact plant or animal tissue, said pieces containing at least 30 wt. % of water, the method comprising (i) contacting the pieces of intact tissue with a pressurized gas to reduce the water content of the pieces by at least 50%, said pressurized gas having a pressure of at least 0.5×Pc and a temperature of at least Tc&minus；60° C., Pc representing the critical pressure of the gas and Tc representing the critical temperature of the gas, and (ii) separating the pressurized gas from the dehydrated pieces, wherein at least 80 wt. %, preferably at least 90 wt. % of the matter removed by the gas from the pieces of intact plant or animal tissue is water. The invention also provides a method of dehydrating a material containing at least 30 wt. % of water, using a method as described before, followed by drying the separated pressurized gas by contacting said pressurized gas with a water absorbent water adsorbent； and recirculating the dried pressurized gas to the partially dehydrated material.
