The invention relates to a process for producing expandable pelletized material which comprises polylactic acid which comprises the following steps: a) melting and incorporation by mixing of polylactic acid, one or more further polymers, a diepoxide or polyepoxide, and one or more additives, b) incorporation by mixing of an organic blowing agent into the polymer melt by means of a static or dynamic mixer at a temperature of at least 140° C., c) discharging through a die plate with holes, the diameter of which at the exit from the die is at most 1.5 mm, and d) pelletizing the melt comprising blowing agent directly downstream of the die plate, and under water, at a pressure in the range from 1 to 20 bar. The invention further relates to expandable pelletized material which comprises polylactic acid and which is obtainable by said process.