Unveiling the compositional remodelling of Arbutus unedo L. fruits during ripening

•The architecture of the cell wall of strawberry tree (Arbutus unedo L.) fruits, during four ripening stages, is herein elucidated for the first time.•Glucose and xylose are the major neutral sugars in the cell wall, similarly to other Ericaceae.•A. unedo fruits are unusually rich in lignin.•Multiple structures of aggregated sclereids are observed in the fruits, thus unveiling their peculiar gritty texture.•Sclereids are the source of high levels of xylose and lignin.