Oligosaccharides are increasingly recognized as dietary-based tools for modulation of the colonic microflora toward a purportedly healthier community structure (Fuller and Gibson 1998). Because they are carbohydrates, their incorporation into foods and drinks like biscuits, cereals, infant formula feeds, carbonated drinks, juices, table spreads and confectioneries has been the chosen way of administration (Crittenden and Playne 1996). Dietary ingredients that can potentially provide beneficial physiological advantages beyond basic nutrition are termed functional foods. For oligosaccharides, this usually involves selectively increasing the levels of gut bifidobacteria and lactobacilli, preferably at the expense of less desirable organisms such as

Escherichia coli

, clostridia and proteolytic bacteroides. This selective fermentation is known as the prebiotic concept (Gibson and Roberfroid 1995).