Sucrosyl oligosaccharides represent the major portion of the so-called primary oligosaccharides, recently defined (Kandler and Hopf 1980a) as those oligosaccharides which are synthesized in vivo by the action of a glycosyl transferase from a mono- or oligosaccharide and a glucosyl donor. They occur freely in significant amounts in plants and are of metabolic relevance, whereas the so-called secondary oligosaccharides arise by the hydrolysis of higher oligosaccharides, polysaccharides, or heterosides and are usually not accumulated in the plant tissue. In all known cases the biosynthesis of the sucrosyl oligosaccharides is brought about by the transfer of a galactopyranosyl, glucopyranosyl, or fructofuranosyl residue to either the glucosyl or fructosyl moiety of sucrose. A survey of the mode of attachment of these residues to sucrose is shown in Fig. 1. The degree of polymerization (DP) normally ranges from three to nine. A set of homologous oligosaccharides is usually designated a series or family, e.g., the raffinose series (family) etc.