A method of producing sialyloligosaccharides a sialyloligosaccharides-containing source that also contains carbohydrates and minerals. The process includes subjecting the source to a temperature of from about 67° C. and (i) filtration with a heat-resistant filter at a temperature of about 35 to about 95° C. to produce a first retentate and first permeate, or (ii) centrifugal separation to produce a light phase and a heavy phase and filtration of the light phase at a temperature of about 50 to about 70° C. to produce a first retentate and first permeate, (b) nanofiltration of the first permeate, or nanofiltration and diafiltration of the first permeate, to produce a second retentate and second permeate, and (c) concentration of the second retentate, to produce a sialyloligosaccharide-containing extract. Additionally, the invention relates to a sialyloligosaccharide-enriched composition comprising at least 3′-sialyllactose and 6′-sialyllactose and its use in, for example, nutritional and infant formulas, and for maintaining or improving cognitive function.