[Food preservation through combined processes].
Food preservation by combined processes is based on the combination of two or more existing preservation methods with the objective of developing milder preservation procedures. Currently two combined processes (CP) deserve a special attention, the preservation of food by high pressures (HP) and the preservation of food with the combined use of heat and ultrasounds under pressure (Mano-Thermo-Sonication). In the preservation by HP, the food, at room temperature or at very mild temperature, is held during relatively long periods under very high pressures (100-1000 MPa) to inactivate its enzymes and/or microorganisms. This procedure has proved to be effective to inactivate vegetative cells but much less effective to inactivate most enzymes and bacterial spores. Several kinds of food preserved by this method have already been launched into the market. In Mano-Thermo-Sonication (MTS Process) microorganisms and enzymes are inactivated by a combined heat/ultrasounds treatment under pressure. By this method, the lethality of heat treatments at the same temperature is highly increased. Therefore, the intensity of heat treatments can be drastically reduced. Heat resistance of spores is reduced by a factor of 1/10 and that of enzymes and vegetative cells is reduced by a factor of 1/50 approximately. The applicability of this procedure is currently being investigated.