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Role of Intestinal Microbiota in Ulcerative Colitis

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Theoretical part<br />

5. Production <strong>of</strong> prebiotics and novel prebiotic candidates<br />

5. Production <strong>of</strong> prebiotics and novel prebiotic candidates<br />

Non‐digestible poly‐ and oligosaccharides <strong>of</strong> various types are found as natural components <strong>in</strong><br />

fruit, vegetables, milk and honey (Crittenden and Playne, 1996). With the exception <strong>of</strong> soybean<br />

oligosaccharides (produced by direct extraction from soybean whey) and lactulose (produced by<br />

alkal<strong>in</strong>e isomerisation <strong>of</strong> lactose), most prebiotic oligosaccharides are manufactured us<strong>in</strong>g<br />

enzymatic processes (Crittenden and Playne, 1996;Rastall, 2007). They are either synthesized from<br />

monosaccharides (such as lactose and sucrose) by transglycosylation reactions or produced by<br />

controlled hydrolysis <strong>of</strong> polysaccharides, <strong>in</strong>clud<strong>in</strong>g starch, <strong>in</strong>ul<strong>in</strong> or xylan (Crittenden and Playne,<br />

1996;Grizard and Barthomeuf, 1999). In this chapter, the production <strong>of</strong> the classified prebiotic<br />

oligosaccharide, FOS, will be described, as well as the production <strong>of</strong> novel prebiotic candidates<br />

derived from pect<strong>in</strong>.<br />

5.1. Fructo-oligosaccharides<br />

FOS is found <strong>in</strong> several k<strong>in</strong>ds <strong>of</strong> plants and vegetables such as banana, onion, asparagus roots,<br />

artichokes, shallot, and wheat (Sangeetha et al., 2005). They are <strong>in</strong>dustrially produced <strong>in</strong> two ways<br />

lead<strong>in</strong>g to different products: either from <strong>in</strong>ul<strong>in</strong> (commercially recovered from chicory root and<br />

Jerusalem artichoke) by hydrolysis or from transfructosylation <strong>of</strong> sucrose (Grizard and<br />

Barthomeuf, 1999).<br />

In commercial <strong>in</strong>ul<strong>in</strong>, both l<strong>in</strong>ear cha<strong>in</strong>s <strong>of</strong> α‐D‐glucopyranosyl‐[β‐D‐fruct<strong>of</strong>uranosyl (l<strong>in</strong>ked 2→1)]n‐<br />

1‐D‐fruct<strong>of</strong>uranoside and β‐D‐fructopyranosyl‐[β‐D‐fruct<strong>of</strong>uranosyl (l<strong>in</strong>ked 2 →1)]n‐1‐D‐<br />

fruct<strong>of</strong>uranoside residues are <strong>in</strong>cluded. The number (n) <strong>of</strong> β‐D‐fruct<strong>of</strong>uranose units varies from<br />

two to more than seventy units (Roberfroid and Delzenne, 1998). The production <strong>of</strong> FOS from<br />

<strong>in</strong>ul<strong>in</strong> is a result <strong>of</strong> partial enzymic hydrolysis us<strong>in</strong>g <strong>in</strong>ul<strong>in</strong>ase (2,1‐β‐D‐fructan fructanohydrolase<br />

(EC 3.2.1.7)). This enzyme is specific for <strong>in</strong>ul<strong>in</strong> and catalyzes the breakdown <strong>of</strong> β‐D‐fructosidic<br />

l<strong>in</strong>kages <strong>in</strong> <strong>in</strong>ul<strong>in</strong> <strong>in</strong> an endo‐type manner. The majority <strong>of</strong> the hydrolysates (FOS: DP2–10; average<br />

DP5) are fruct<strong>of</strong>uranosyl residues, but a low proportion term<strong>in</strong>ates <strong>in</strong> glycosyl residues (Roberfroid<br />

and Delzenne, 1998;Grizard and Barthomeuf, 1999).<br />

The <strong>in</strong>dustrial production <strong>of</strong> FOS from sucrose uses ma<strong>in</strong>ly fructosyltransferase or β‐<br />

fruct<strong>of</strong>uranosidase from bacterial and fungal sources (Yun et al., 1997;Kim et al., 1998). FOS<br />

derived from sucrose all term<strong>in</strong>ate <strong>in</strong> glucosyl residues, and are thus non‐reduc<strong>in</strong>g. Additionally,<br />

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