Oligoxyloglucan-reducing end-specific xyloglucanase involved in degradation of xyloglucans. Releases the first two glycosyl segments from oligoxyloglucans. Active against cotton xyloglucan, tamarind xyloglucan and tamarind xyloglucan oligomers (Probable). Hydrolysis of cellobiose from the reducing end of xyloglucans consisting of a beta-(1->4)-linked glucan carrying alpha-D-xylosyl groups on O-6 of the glucose residues. To be a substrate, the first residue must be unsubstituted, the second residue may bear a xylosyl group, whether further glycosylated or not, and the third residue, which becomes the new terminus by the action of the enzyme, is preferably xylosylated, but this xylose residue must not be further substituted. Optimum pH 3.0. Optimum temperature is 42 degrees Celsius. Belongs to the glycosyl hydrolase 74 family.