Improvement of a previously described method of purification of α-galactosides, members of the raffinose family of oligosaccharides (RFOs), has been developed for lupins. The considerable amount of sucrose present in the RFO preparations obtained by the previous method has been removed by modifying the purification stage on diatomaceous earth and charcoal. The present method allows for the preparation of high-purity RFOs containing ∼99.4% of RFOs in the form of a white fine powder, which provides new perspectives for the production of pure α-galactoside preparations for their use as prebiotics in functional foods.