Abstract: A process for the preparation of particulate acylated biopolymer comprising anhydroglucose units that comprises several steps. First, dispersing an amount of particulate non-surface modified biopolymer comprising anhydroglucose units in an amount of a liquid alkenyl carboxylatein order to form a first dispersion. Then, adding a catalytic composition to the first dispersion such a to form a second dispersion, heating the second dispersion to a temperature above ambient temperature, and cooling the second dispersion to ambient temperature. Thereafter, the obtained particulate acylated biopolymer is isolated. The amount of a liquid alkenyl carboxylate corresponds to a molar excess of alkenyl carboxylate, the molar excess being defined with respect to the moles of anhydroglucose units comprised in the amount of the particulate non-surface modified biopolymer. The catalytic composition comprises an amount of one, or two or more, non-nucleophilic bases.