Foaming is a general problem in the manufacturing of fatty polyamides. It is mainly affected by the mixing rate and reaction temperature. The effect of the reaction temperature and rate of mixing on foaming are investigated. Time minimization for the polyamidation reaction to prevent foaming is performed. The process constraints are the rate of temperature increase and the rate of the production of water. It is found that with an increase in the mixing rate, foaming starts at lower temperatures and with a decrease in the mixing rate, foaming only starts at high temperatures. For each mixing rate, with an increase in the temperature, the duration of foaming is shorter because the increase in the rate of foaming ends. Temperature profiles with time for different mixing rates are generated, and it is found that the reaction time decreases with increasing mixing rate. The generated temperature profiles are verified experimentally, and no foaming is observed. (c) 2005 Wiley Periodicals, Inc.