Milk oligosacarides

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International Dairy Journal 16 (2006) 1334–1340 www.elsevier.com/locate/idairyj

Review

Milk oligosaccharides: Structural and technological aspects
R. MehraÃ, P. Kelly
Moorepark Food Research Centre, Teagasc, Fermoy, Co. Cork, Ireland Received 31 August 2005; accepted 29 May 2006

Abstract This review focuses on the more recent scientific information on composition andstructural aspects of human and bovine milk oligosaccharides (OS). Advances in high performance liquid chromatography and capillary electrophoresis techniques have been at the forefront in making available efficient analytical methods for OS quantification. More sophisticated tools are available to assist with structural characterisation of milk OS. Furthermore, the review deals with existing andemerging technologies that have a potential for use in large scale fractionation/enrichment of OS, leading to the production of fractions rich in milk OS for use as physiologically active health promoting ingredients in functional dairy foods. r 2006 Elsevier Ltd. All rights reserved.
Keywords: Milk oligosaccharides; Structure; Analysis; Production

Contents 1. 2. 3. Introduction . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Composition and structure of milk oligosaccharides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Analytical techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1. Methods for quantification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2. Methods for structural analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Methods for oligosaccharideproduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1334 1335 1335 1335 1337 1338 1338 1339

4. 5.

1. Introduction Complex oligosaccharides constitute a large portion of the total solids of human milk (Gopal & Gill, 2000). Human milk oligosaccharides perform biological functions that are closely related to their structural conformation. They contribute to the growth of beneficialintestinal flora in the colon, postnatal stimulation of the immune system, and provide defence against bacterial and viral infections by acting as competitive inhibitors for binding sites on the
ÃCorresponding author. Tel.: +353 25 42433; fax: +353 25 42340.

E-mail address: Raj.Mehra@teagasc.ie (R. Mehra). 0958-6946/$ - see front matter r 2006 Elsevier Ltd. All rights reserved.doi:10.1016/j.idairyj.2006.06.008

intestinal epithelial surface (Kunz, Rudloff, Baier, Klien, & Strobel, 2000). Compositional and structural analysis of the complex structural diversity of milk oligosaccharides necessitates the use of appropriate sophisticated and powerful analytical methods and equipment. Depending on the type, size, structure, and source of the oligosaccharides, numerous publications havebeen published on a variety of analytical techniques used to characterise oligosaccharide composition and structure. Compared with human milk/colostrum, the levels of oligosaccharides in milk of domestic mammalian animals (cows, sheep, and goat) are much lower (Urashima, Murata, & Nakamura, 1997). The low concentration of oligosaccharides present in

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