Abstract: In the process for the concentration of volatiles-bearing products by a low-temperature, short-time, multi-effect evaporation method, a forward feed of the product and vapor occurs so that at least from a given stage of evaporation, each subsequent stage of evaporation is carried out at a lower temperature. The volatile constituents, removed with the vapor from one or more effects and subsequently condensed and recovered, are combined with the partially concentrated product before a final stage or stages of evaporation at a temperature lower than that at which they were originally distilled off. Thus a more highly volatile fraction is again removed with the vapor in the said final stage or stages of evaporation.