The definition of dietary fiber – discussions at the Ninth Vahouny Fiber Symposium: building scientific agreement

A definition for dietary fiber was adopted in June 2009 by the Codex Alimentarius Commission based on the recommendation for endorsement of the Codex Committee on Nutrition and Foods for Special Dietary Uses (CCNFSDU) in November 2008. The definition listed three categories of carbohydrate polymers that are not hydrolyzed by the endogenous enzymes in the small intestine of humans. However, the definition left the inclusion of carbohydrates with degrees of polymerization (DP) in the range of 3 and 9 to the discretion of national authorities and left the ‘physiological effect(s) of benefit to health’ as undefined. The ILSI Europe and ILSI North America's committees on dietary carbohydrates organized a forum at the Ninth Vahouny Fiber Symposium in 2010 to discuss these implementation issues with the objective of building scientific consensus on how to resolve them. The results of this session are encouraging and indicated that the scientific community agrees on maintaining a worldwide consensus regarding the inclusion of non-digestible carbohydrates with ≥DP3 as dietary fiber and on a core, non-exhaustive list of beneficial physiological effects that dietary fibers have. These results are consistent with previous worldwide agreements

(1R,2R,3S,6aS,7R,8R,9S,12aS)-1,2,3,7,8,9-Hexahydroxy­perhydro­dipyrido[1,2-a:1′,2′-d]pyrazine-6,12-dione

The crystal structure of the title compound, C12H18N2O8, exists as O—H⋯O hydrogen-bonded layers of mol­ecules running parallel to the ab plane. Each mol­ecule is a donor and acceptor for six hydrogen bonds. The absolute stereochemistry was determined by the use of d-glucuronolactone as the starting material

Nitrogen Leaching from Cattle, Sheep and Deer Grazed Pastures in New Zealand

The impacts of intensified grazing in New Zealand are being reflected in declining quality of groundwater, streams and lake water. Manipulation of ratios of grazing animal species may be one way farmers can reduce nitrogen (N) emissions to ground water. The present research quantifies nitrate and ammonium leaching losses from rotationally grazed sheep, cattle and deer pastures in a common environment

(S)-3-Dimethyl­amino-2-{(4S,5R)-5-[(R)-2,2-dimethyl-1,3-dioxolan-4-yl]-2,2-dimethyl-1,3-dioxolan-4-yl}-2-hydroxy­propanoic acid

The Kiliani reaction on 1-de­oxy-(N,N-dimethyl­amino)-d-fructose, itself readily available from reaction of dimethyl­amine and d-glucose, proceeded to give access to the title β-sugar amino acid, C15H27NO7. X-ray crystallography determined the stereochemistry at the newly formed chiral center. There are two mol­ecules in the asymmetric unit; they are related by a pseudo-twofold rotation axis and have very similar geometries, differing only in the conformation of one of the acetonide rings. All the acetonide rings adopt envelope conformations; the flap atom is oxygen in three of the rings, but carbon in one of them. There are two strong hydrogen bonds between the two independent mol­ecules, and further weak hydrogen bonds link the mol­ecules to form infinite chains running parallel to the a axis

N-Benzyl-1,3-dide­oxy-1,3-imino-l-xylitol

The structure determination confirms the stereochemistry of the title compound, C12H17NO3, which contains a four-membered azetidine ring system. The absolute configuration was determined by the use of d-glucose as the starting material. In the crystal, O—H⋯O and O—H⋯N hydrogen bonds link the mol­ecules into layers in the ab plane

6-De­oxy-α-l-talopyran­ose

X-ray crystallography showed that the title compound, C6H12O5, crystallizes in the α-pyran­ose form with the six-membered ring in a chair conformation. The crystal structure exists as a three-dimensional hydrogen-bonded network of mol­ecules with each mol­ecule acting as a donor and aceptor for four hydrogen bonds. The absolute configuration was determined by the use of l-fucose as starting material

1-(1-Carboxy­methyl-1,4-anhydro-2,3-O-isopropyl­idene-α-d-erythrofuranos­yl)thymine

X-Ray crystallography unequivocally determined the stereochemistry of the thymine base in the title compound, C14H18N2O7. The absolute stereochemistry was determined from the use of d-ribose as the starting material. There are two independent mol­ecules in the asymmetric unit (Z′ = 2) which exist as N—H⋯O hydrogen-bonded pairs in the crystal structure

7-Azido-N,N-diethyl-4,5-O-isopropyl­idene-4-C-methyl-3,6-anhydro-7-de­oxy-d-glycero-d-manno-heptonamide

The reaction of 5-azido-5-de­oxy-2,3-O-isopropyl­idene-2-C-methyl-d-ribose with N,N-diethyl-2-(dimethyl­sulfuranyl­idene)acetamide gave the title compound, C15H26N4O5, as the major product arising from initial formation of an epoxide which was subsequently opened by intra­molecular attack of the free 4-hydroxyl group. X-ray crystallography confirmed the relative stereochemistry of the title compound and the absolute configuration was determined by the use of d-ribose as the starting material. The crystal structure contains chains of mol­ecules running parallel to the a axis, being linked by weak bifurcated O—H⋯(N,N) hydrogen bonds

1-De­oxy-d-galactitol (l-fucitol)

1-De­oxy-d-galactitol, C6H14O5, exists in the crystalline form as hydrogen-bonded layers of mol­ecules running parallel to the ac plane, with each mol­ecule acting as a donor and acceptor of five hydrogen bonds