Bioactive Polysaccharides from Seaweeds.

Bioactive compounds with diverse chemical structures play a significant role in disease prevention and maintenance of physiological functions. Due to the increase in industrial demand for new biosourced molecules, several types of biomasses are being exploited for the identification of bioactive metabolites and techno-functional biomolecules that are suitable for the subsequent uses in cosmetic, food and pharmaceutical fields. Among the various biomasses available, macroalgae are gaining popularity because of their potential nutraceutical and health benefits. Such health effects are delivered by specific diterpenes, pigments (fucoxanthin, phycocyanin, and carotenoids), bioactive peptides and polysaccharides. Abundant and recent studies have identified valuable biological activities of native algae polysaccharides, but also of their derivatives, including oligosaccharides and (bio)chemically modified polysaccharides. However, only a few of them can be industrially developed and open up new markets of active molecules, extracts or ingredients. In this respect, the health and nutraceutical claims associated with marine algal bioactive polysaccharides are summarized and comprehensively discussed in this review.

Optimization of energy recovery efficiency from sweet sorghum stems by ethanol and methane fermentation processes coupling.

Taken separately, a single sweet sorghum stem bioconversion process for bioethanol and biomethane production only leads to a partial conversion of organic matter. The direct fermentation of crushed whole stem coupled with the methanization of the subsequent solid residues in a two-stage process was experimented to improve energy bioconversion yield, efficiency, and profitability. The raw stalk calorific value was 17,144.17 kJ/kg DM. Fermentation step performed using Saccharomyces cerevisiae resulted in a bioconversion yield of 261.18 g Eth/kg DM, i.e. an energy recovery efficiency of 6921.27 kJ/kg DM. The methanogenic potentials were 279 and 256 LCH4/kg DM, respectively, for raw stem and fermentation residues, i.e. energy yields of 10,013.31 and 9187.84 kJ/kg DM, respectively. Coupling processes have significantly increased yield and made it possible to reach 13,309.57 kJ/kg DM, i.e. 77.63% of raw stem energy recovery yield, compared to 40.37% and 58.40%, respectively, for single fermentation and methanization processes.

Sweet sorghum stem is a viable feedstock source for efficient coproduction of ethanol and methaneSorghum stems calorific value determination revealed an energy potential of 17.15 MJ/kg DMEnergy recovery by single methanization yielded 18.03% more than ethanol fermentationCoupling processes has significantly increased energy recovery yield and profitability.

Plants arabinogalactans: From structures to physico-chemical and biological properties.

Arabinogalactans (AGs) are plant heteropolysaccharides with complex structures occasionally attached to proteins (AGPs). AGs in cell matrix of different parts of plant are freely available or chemically bound to pectin rhamnogalactan. Type I with predominantly ß-d-(1 â†’ 4)-galactan and type II with ß-d-(1 â†’ 3) and/or (1 â†’ 6)-galactan structural backbones construct the two main groups of AGs. In the current review, the chemical structure of AGs is firstly discussed focusing on non-traditional plant sources and not including well known industrial gums. After that, processes for their extraction and purification are considered and finally their techno-functional and biological properties are highlighted. The role of AG structure and function on health advantages such as anti-tumor, antioxidant, anti-ulcer- anti-diabetic and other activites and also the immunomodulatory effects on in-vivo model systems are overviewed.