The invention concerns a process to convert di-rhamnolipid to mono-rhamnolipid comprising the following process steps: (a) contact of a starting di-rhamnolipid material with an -L-rhamnosidase enzyme which is immobilised on a support; (b) separation of the produced mono-rhamnolipid from the reaction medium and/or side products; wherein the -L-rhamnosidase enzyme does not have -D-glucosidase activity.

Methods for the enzymatic modification of saponins produced in plant cell culture, products made thereby, uses of said products and also to other associated aspects. The saponins may be obtained from plant cell culture extracts of Quillaja species, such as extracts of Quillaja saponaria Molina.