Methods suitable for selecting optimal defoamers for use in fermentation processes are described wherein the methods comprise: (a) determining an amount of each of two or more defoamers which provides a requisite dynamic surface tension of at most 50 mN/m at a particular frequency in a fermentation medium; and (b) selecting the defoamer which provides the requisite dynamic surface tension at the lowest amount. Methods for controlling foam by determining and adjusting dynamic surface tension are also described.