Alternatively, the pressure vessel can additionally be designed as a pressure intensifier. The pressure vessel is built to withstand a certain amount of pressure and temperature, and contains the packaged food product and pressurization fluid. Pressure vessel sizes are defined by the volume of fluid that the vessel can hold, and can range from several milliliters for research units to several hundred liters for commercial units. The pressurization fluid is typically water, and is added to the pressure vessel to eliminate air pockets between the packages of food. Once the pressurization fluid is added, the hydraulic pressure intensifier and pump are used to increase the pressure inside the cell and the pressure is transmitted through the pressurization fluid through the packaging material to the food itself. As the pressure is applied uniformly over the whole surface of the food product, the shape of the food is maintained.