The procedure uses the osmotic dehydration of food by means of a controlled alternating change of pressures in order to improve the exchanges of water and solutes between the food and a surrounding liquid medium. Vacuum is used to drive the air out of the pores and refill them at the end of the process; the changes in pressure are used as a means of pumping the solution inside the pores, it being possible to carry out said pumping once (in general in the case of preserves) or repeatedly (in the case of salting food); the duration of each vacuum pulse is 1/2 or less than the duration of the process, which is between 1 and 10 hours, with working temperatures of between 8 and 20°C lower than in the case of conventional processes as well as times which are 2 to 4 times shorter, thereby providing a considerable improvement in terms of maintaining the taste, aroma and nutritional components. Equipment for carrying out the process is also described.