Hot-Water Hemicellulose Extraction from Fruit Processing Residues.

Hemicelluloses are an abundant biopolymer resource with interesting properties for applications in coatings and composite materials. The objective of this investigation was to identify variables of industrially relevant extraction processes that increase the purity of hemicelluloses extracted from fruit residues. Our main finding is that extraction with subcritical water, followed by precipitation with alcohol, can be adjusted to yield products with a purity of at least 90%.

Does the Food Ingredient Pectin Provide a Risk for Patients Allergic to Non-Specific Lipid-Transfer Proteins?

Pectin, a dietary fiber, is a polysaccharide that is widely used in food industry as a gelling agent. In addition, prebiotic and beneficial immunomodulatory effects of pectin have been demonstrated, leading to increased importance as food supplement. However, as cases of anaphylactic reactions after consumption of pectin-supplemented foods have been reported, the present study aims to evaluate the allergy risk of pectin.

Processes involving selective precipitation for the recovery of purified pectins from mango peel.

Three methods for the recovery of purified pectins from directly dried mango peel were developed, using selective precipitation of mango pectin in propan-2-ol (IPA) of adequate volume concentrations for purification. Yields, composition, macromolecular and gelling properties of the resultant pectins were compared. Effluent analyses proved postextractive removal of fruit exudate arabinogalactans.

Efficient synthesis of building blocks for branched rhamnogalacturonan I fragments.

Starting from allyl 2-O-acetyl-3-O-benzyl-α-l-rhamnopyranoside (3), allyl (2,3,4,6-tetra-O-benzoyl-β-d-galactopyranosyl)-(1→4)-2-O-acetyl-3-O-benzyl-α-l-rhamnopyranoside (5) was synthesized under Helferich conditions. Module 5 was converted to 2,3,4,6-tetra-O-benzoyl-β-d-galactopyranosyl-(1→4)-2-O-acetyl-3-O-benzyl-α-l-rhamnopyranosyl bromide (8) which was then coupled with methyl (allyl 2,3-di-O-benzyl-β-d-galactopyranosid)uronate (11) to provide methyl (2,3,4,6-tetra-O-benzoyl-β-d-galactopyranosyl)-(1→4)-(2-O-acetyl-3-O-benzyl-α-l-rhamnopyranosyl)-(1→4)-(allyl 2,3-di-O-benzyl-β-d-galactopyranosid)uronate (14). Alternatively, module 5 was transformed into allyl 2,3,4,6-tetra-O-benzoyl-β-d-galactopyranosyl-(1→4)-3-O-benzyl-α-l-rhamnopyranoside (9) suitable as an acceptor for the glycosylation with methyl 4-O-acetyl-2,3-di-O-benzyl-α/β-d-galactopyranosyluronate N-phenyl trifluoroacetimidate (13) to yield allyl (methyl 4-O-acetyl-2,3-di-O-benzyl-α-d-galactopyranosyluronate)-(1→2)-[2,3,4,6-tetra-O-benzoyl-β-d-galactopyranosyl]-(1→4)-3-O-benzyl-α-l-rhamnopyranoside (15).

Synthesis of rhamnogalacturonan I fragments by a modular design principle.

The improved syntheses of methyl 2-O-acetyl-3-O-benzyl-alpha-L-rhamnopyranoside (12) and 1,2-di-O-acetyl-3-O-benzyl-alpha-L-rhamnopyranose (15), which were used as glycosyl acceptor and donor, respectively, are described. Glycosylation of the O-4 position of both rhamnose derivatives with 2,3,4,6-tetra-O-benzoyl-alpha-D-galactopyranosyl bromide (26) provided disaccharides 27 and 29. After partial deprotection of 27 and coupling of the resulting 28 with disaccharide 19, tetrasaccharide 31 was obtained.