Abstract: A process and apparatus are provided for controlling the temperature of various phases in the winemaking process by means of a heat-exchanging fluid circulating in at least one flexible exchanger, the thermoregulating action of which is exerted in a horizontal plane to favor stratification of the temperatures.The apparatus comprises at least one removable heat exchanger consisting of a flexible or semirigid tubular structure made of a neutral material whose density is less than the density of the winemaking juice. The structure is placed in a horizontal plane in the winemaking vat.