Fruit purees are very difficult to pasteurize/sterilize because of their viscosity. The high viscosity makes the uniform heating of the entire product very difficult in a short amount of time.
To be sure of the uniformity of the heating tubular heat exchangers are used, but the high pressure drops in the pipes limit the speed of the product in the system with unavoidable over-heating of the surface of the product flowing in the pipes.
The WAVE is heating instantaneously and uniformly the product in a short pipe ensuing the best sterilization/pasteurization process.