The invention provides methods and devices for heating or cooling viscous materials such as meat emulsions useful for producing food and other products. The devices include a heat exchanger comprising a first plate, a second plate attached to the first plate, and a first spacer and a second spacer arranged between the first plate and the second plate. The first plate, the second plate, the first spacer and the second spacer define a temperature controlled passage for a product to pass through the heat exchanger. The heat exchanger further includes a third plate attached to the second plate, and a third spacer and a fourth spacer arranged between the second plate and the third plate. The second plate, the third plate, the third spacer and the fourth spacer define another temperature controlled passage for a second product to pass through the heat exchanger.
