Alpha-galactosidase involved in the degradation of simple oligosaccharides like melibiose, raffinose and stachyose, and of polymeric galacto(gluco)mannans. Hydrolysis of terminal, non-reducing alpha-D-galactose residues in alpha-D-galactosides, including galactose oligosaccharides, galactomannans and galactolipids. Optimum pH is 3.5-4.5. Belongs to the glycosyl hydrolase 27 family.