Involved in the hydrolysis of the galactomannan, it splits alpha-linked galactose moieties. It is particularly suitable for the hydrolysis of guar gum to a gum with improved gelling properties. Preferentially cleaves alpha-1,6 glycoside linkages. Hydrolysis of terminal, non-reducing alpha-D-galactose residues in alpha-D-galactosides, including galactose oligosaccharides, galactomannans and galactolipids. Belongs to the glycosyl hydrolase 27 family.