Merilyn Manley-Harris

Di-d-fructose dianhydrides and related oligomers from thermal treatments of inulin and sucrose

Thermal treatment of anhydrous, acidified sucrose or inulin yields caramels containing monosaccharides and oligomers, predominantly dianhydrides and higher oligomers derived by the addition of glycosyl residues to dianhydrides. Fourteen dianhydrides, most of which comprise two fructose moieties, have been identified by mass spectroscopy of the per-O-trimethylsilyl ethers. Thirteen of these dianhydrides have been isolated and characterized; five of the dianhydrides are novel compounds and one of these is a glucose-fructose dianhydride. The dianhydrides and related oligomers are thought to have a prebiotic effect by stimulating the proliferation of bifidobacteria in the large intestine.

A novel fructoglucan from the thermal polymerization of sucrose

Abstract The heating of anhydrous, amorphous, acidified sucrose produces a novel fructoglucan in ≈30% yield; it contains d -fructose and d -glucose in a ≈1:2 ratio. It is highly branched and of relatively low molecular weight; gel-permeation chromatography indicates an average dp ≈25. Methylation analysis was complicated by acid degradation of the methylated fructose units under conditions for hydrolysis of glucopyranoside linkages. Parallel application of three different, hydrolytic regimes indicated linkages predominantly through O-6 of glucopyranoside and O-1 of fructofuranoside residues. Most of the nonreducing end groups are glucopyranose and both single and double branch-points are present. The fructoglucan is similar in molecular size and architecture to a commercial glucan, Polydextrose™, which finds extensive use as a noncalorific food-bulking agent.

Formation of trisaccharides (kestoses) by pyrolysis of sucrose

Amorphous sucrose, containing citric acid as catalyst, undergoes thermolysis at 100 degrees to yield fructofuranosyl cation and D-glucose. The cation reacts with unchanged sucrose to form all three of the known kestoses, and also their alpha-fructofuranosyl anomers. Two of the latter are resistant to invertase hydrolysis. A new fructosylglucose disaccharide is also formed.

Di-d-fructose dianhydrides from the pyrolysis of inulin ☆

Inulin was pyrolyzed in air to produce di-D-fructose dianhydrides (DFDAs) in approximately 26% yield, three of which were identified by MS, NMR, and comparison with literature data. The mass spectra of the per-O-trimethylsilyl derivatives of the DFDAs are discussed. A mechanism is proposed for the formation of DFDAs from inulin during pyrolysis.

Structural studies by NMR spectroscopy of the major oligomers from alkali-degraded arabinoigalactan from Larix occidentalis

Abstract Oligomers with terminal metasaccharinic acid residues have been derived from branches on the main chain of arabinogalactan by alkaline degradation. The major oligomers present have been studied by NMR. Individual oligomers existed as epimeric pairs in the approximate ratio 1.5:1. This study confirmed the presence of branches consisting of a single β- d -Ga1 p residue, of two or three β- d -Gal p residues linked (1→6) or of two β-D-Ga1 p residues linked (1→6) with the proximate residue further substituted at O-3 by an α- L -arabinofuranosyl residue.

Stereoselective thermal transfer of fructose from sucrose to cyclodextrins

Branched cyclodextrins (CDs) have been formed by the thermal transfer of a fructosyl group from sucrose to O-6 of one of the glucose residues of cyclomaltohexa- and hepta-ose (alpha-CD and beta-CD). In each case the fructosyl group adds almost entirely in the beta configuration. The resultant fructosylcyclodextrins (Fru-CDs) show increased solubility in water and, in the case of Fru-beta-CD increased ability to solubilize sparingly soluble compounds by inclusion, relative to the parent cyclodextrins. However, the Fru-CDs have similar abilities to form complexes as their respective parent CDs. Fru-CDs act as inhibitors of invertase.

Anhydro sugars and oligosaccharides from the thermolysis of sucrose

Thermolysis of anhydrous, amorphous, acidified sucrose results in polymerization initially involving the fructosyl cation and later the glucosyl cation. Monomeric and dimeric anhydro sugars form during the thermolysis and are incorporated into the fructoglucan polymer.