The invention relates to a composition comprising: at least one aliphatic polyester (A) comprising diols containing at least ethylene glycol, 1,4-butanediol or mixtures thereof and diacids containing at least succinic acid, adipic acid or mixtures thereof; at least one starch (B); at least one organic plasticiser (C) for starch; optionally, an additional polyester or a mixture of additional polyesters (D) different from polyester (A). The composition is characterised in that it also comprises citric acid (E), the amount by weight of citric acid varying between 0.01 and 0.45 parts per 100 parts of the total dry weight of (A), (B), (C) and (D).