Structures of the xyloglucans in the monocotyledon family Araceae (aroids).

MAIN CONCLUSION: The xyloglucans of all aquatic Araceae species examined had unusual structures compared with those of other non-commelinid monocotyledon families previously examined. The aquatic Araceae species Lemna minor was earlier shown to have xyloglucans with a different structure from the fucogalactoxyloglucans of other non-commelinid monocotyledons. We investigated 26 Araceae species (including L. minor), from five of the seven subfamilies. All seven aquatic species examined had xyloglucans that were unusual in having one or two of three features: < 77% XXXG core motif [L. minor (Lemnoideae) and Orontium aquaticum (Orontioideae)]; no fucosylation [L. minor (Lemnoideae), Cryptocoryne aponogetonifolia, and Lagenandra ovata (Aroideae, Rheophytes clade)]; and > 14% oligosaccharide units with S or D side chains [Spirodela polyrhiza and Landoltia punctata (Lemnoideae) and Pistia stratiotes (Aroideae, Dracunculus clade)]. Orontioideae and Lemnoideae are the two most basal subfamilies, with all species being aquatic, and Aroideae is the most derived. Two terrestrial species [Dieffenbachia seguine and Spathicarpa hastifolia (Aroideae, Zantedeschia clade)] also had xyloglucans without fucose indicating this feature was not unique to aquatic species.

Brown Algae Carbohydrates: Structures, Pharmaceutical Properties, and Research Challenges.

Brown algae (Phaeophyceae) have been consumed by humans for hundreds of years. Current studies have shown that brown algae are rich sources of bioactive compounds with excellent nutritional value, and are considered functional foods with health benefits. Polysaccharides are the main constituents of brown algae; their diverse structures allow many unique physical and chemical properties that help to moderate a wide range of biological activities, including immunomodulation, antibacterial, antioxidant, prebiotic, antihypertensive, antidiabetic, antitumor, and anticoagulant activities. In this review, we focus on the major polysaccharide components in brown algae: the alginate, laminarin, and fucoidan. We explore how their structure leads to their health benefits, and their application prospects in functional foods and pharmaceuticals. Finally, we summarize the latest developments in applied research on brown algae polysaccharides.

Reactive compatibilization of plant polysaccharides and biobased polymers: Review on current strategies, expectations and reality.

Our society is amidst a technological revolution towards a sustainable economy, focused on the development of biobased products in virtually all sectors. In this context, plant polysaccharides, as the most abundant macromolecules present in biomass represent a fundamental renewable resource for the replacement of fossil-based polymeric materials in commodity and engineering applications. However, native polysaccharides have several disadvantages compared to their synthetic counterparts, including reduced thermal stability, moisture absorption and limited mechanical performance, which hinder their direct application in native form in advanced material systems. Thus, polysaccharides are generally used in a derivatized form and/or in combination with other biobased polymers, requiring the compatibilization of such blends and composites. In this review we critically explore the current status and the future outlook of reactive compatibilization strategies of the most common plant polysaccharides in blends with biobased polymers. The chemical processes for the modification and compatibilization of starch and lignocellulosic based materials are discussed, together with the practical implementation of these reactive compatibilization strategies with special emphasis on reactive extrusion. The efficiency of these strategies is critically discussed in the context on the definition of blending and compatibilization from a polymer physics standpoint; this relies on the detailed evaluation of the chemical structure of the constituent plant polysaccharides and biobased polymers, the morphology of the heterogeneous polymeric blends, and their macroscopic behavior, in terms of rheological and mechanical properties.

Adhesion and micromechanical deformation processes in PLA/CaSO4 composites.

PLA/CaSO4 composites were prepared from uncoated and stearic acid coated filler particles in a wide composition range. The strength of interfacial adhesion was estimated quantitatively with three independent methods. Structure was characterized by DSC, XRD and SEM measurements, while mechanical properties by tensile and instrumented impact tests. The results proved that adhesion is twice as strong in composites prepared with the uncoated particles than in those containing the coated filler. Coating changes also local deformation processes around the particles. Although debonding is the dominating micromechanical deformation process in all composites, local plastic deformation is larger around coated particles. The extent of this deformation depends very much also on the local distribution of particles. The final properties and performance of the composites depend unambiguously on the micromechanical deformation processes occurring during loading, on debonding and the subsequent plastic deformation. Stearic acid used for the coating of the filler seems to dissolve in the polymer and locally change its properties.