Primary stages study for lignocellulosic biomass thermal degradation

La biomasse est une source d'énergie renouvelable qui capte et stock le CO2. Les objectifs de ce travail ont été d'étudier les comportements thermiques de la biomasse et de ses constituants (cellulose, hémicellulose et lignine). Nous nous sommes plus particulièrement intéressés aux mécanismes de dégradation thermique des polymères naturels survenant en premier dans les traitements thermiques(les mécanismes primaires). Ce travail a été réalisé dans le cadre de l'ACI "Biomasters" avec le soutien du crédit mutuel. Les comportements thermiques de différentes biomasses et de ses constituants ont été étudiés en utilisant la thermogravimétrie (ATG), la pyrolyse couplée à la spectrométrie de masse (Py-SM) et la pyrolyse couplée à la chromatographie gazeuse avec détection par spectrométrie de masse(Py-CG/SM). Nous avons montré, par ATG, que les comportements thermiques des constituants sont sensiblement différents et précisé leurs rôles dans la dégradation thermique. Nous avons aussi montré l'impossibilité de proposer des lois prévisionnelles du comportement thermique d'une biomasse sur la base des résultats obtenus pour ses constituants. En Py-SM nous avons développé une méthode permettant de mettre en évidence les fragments moléculaires les plus représentatifs de la dégradation thermique. Ceci nous a permis de préciser les constituants les plus sensibles à l'action de catalyseurs métalliques. L'analyse Py-CG/SM des mélanges a montré que les compositions des vapeurs dans les mélanges sont proches de lois d'addition simples. Nous terminons notre travail par une application de la pyrolyse / gazéification du Miscanthus pour la production d'un gaz à bonne valeur énergétiqueBiomass is a renewable energy source, which collect and stock CO2. The objectives of this work were to study the thermal behavior of natural biomass and its components (cellulose, hemicellulose and lignin). We were particularly interested in the thermal degradation mechanisms of natural polymers arising, first, during heat treatments (primary mechanisms). This work was carried out with in the framework of the ACI "Biomasters" with the support of Credit Mutuel. The thermal behaviors of biomass and its components were studied by using thermogravimetry (TGA), pyrolysis coupled with mass spectrometry(Py-MS) and pyrolysis coupled with gas chromatography with detection by mass spectrometry (Py-GC/MS). The thermal behaviors of biomass components were shown, by TGA, to be appreciably different and their roles were specified in thermal degradation. We also showed the impossibility of proposing estimated laws of biomass thermalbehavior on the basis of the main component TGA results. With Py-MS, we developed a method allowing to highlight the most representative molecular fragments evolved during biomass thermal degradation. This enabled us to specify the most sensitive components towards metallic catalystaction. The Py-CG/SM analysis of the mixtures showed that vapor compositions in the mixtures are close to simple laws of addition. We complete our work by an application of pyrolysis/gasification of Miscanthus for the of a sas with valu

Strategies for increasing lipid accumulation and recovery from

Microbial-based biodiesel is produced by transesterification of lipids extracted from microbial cells, and is considered as a potential replacement of fossil fuel due to its advantages in reducing greenhouse gas emissions. Yarrowia lipolytica is one of the most studied oleaginous yeasts able to produce lipids under some fermentation conditions and is considered as a potential industrial host for biodiesel production. Several approaches have been evaluated to increase the economical attraction of biodiesel production from Y. lipolytica lipids. In this review, we highlighted the different strategies reported in the literature, allowing this yeast to achieve high lipid accumulation. These include metabolic engineering strategies, the use of low-cost effective substrates, and the optimization of the cultivation conditions for higher lipid productivity and less operating cost. We also summarized the most effective cell disruption technologies that improve the extraction efficiencies of lipids from Y. lipolytica

Theoretical analysis of the "green" synthesis of aniline by reduction of nitrobenzene

Recently a new chemical production means was proposed for producing aniline by reducing nitrobenzene in a much more environmentally friendly way (Tadrent et al., 2018). In particular, activated carbon and water are used instead of hydrogen on a metal catalyst without a precise detail of the process. In the present paper, a theoretical analysis is proposed based on a step by step thermodynamic examination of elementary reactions. It is found that the Haber mechanism is theoretically possible but that due to the size of the pores of the carbon, inside which the reduction occurs, only the smallest molecules can move so that the “direct” path is favored. This can explain why the yield is rather good

Valorization of Brewers’ Spent Grains: Pretreatments and Fermentation, a Review

Brewers’ spent grains constitute a valuable byproduct of the beer industry. They are characterized by a rich nutritional composition consisting of around 70% lignocellulosic fibrous material, 20% proteins, 10% lipids, in addition to vitamins, minerals, amino acids, and phenolic compounds. These spent grains are produced in large amounts all through the year, are cheap, and lack economically feasible applications. Nowadays, 70% of these spent grains are used as animal feed, 10% are used for biogas production, and the remaining 20% are disposed in landfills. Due to the aforementioned facts, alternative uses of the brewers’ spent grains are highly sought-after. In fact, this nutrient-rich industrial by-product makes it a very good candidate for valorization through biotechnological processing, particularly microbial fermentation. After applying the needed pretreatments, using brewers’ spent grains as a substrate in submerged and solid-state fermentation of different microorganisms leads to the production of various value-added compounds such as organic acids, amino acids, volatile fatty acids, enzymes, vitamins, second-generation biofuels and other products

Bioavailability of Glucosinolates and Their Breakdown Products: Impact of Processing

Glucosinolates are a large group of plant secondary metabolites with nutritional effects, and are mainly found in cruciferous plants. After ingestion, glucosinolates could be partially absorbed in their intact form through the gastrointestinal mucosa. However, the largest fraction is metabolized in the gut lumen. When cruciferous are consumed without processing, myrosinase enzyme present in these plants, hydrolyzes the glucosinolates in the proximal part of the gastrointestinal tract to various metabolites such as isothiocyanates, nitriles, oxazolidine-2-thiones and indole-3-carbinols. When cruciferous are cooked before consumption, myrosinase is inactivated and glucosinolates transit to the colon where they are hydrolyzed by the intestinal microbiota. Numerous factors such as storage time, temperature, and atmosphere packaging, along with inactivation processes of myrosinase are influencing the bioavailability of glucosinolates and their breakdown products. This review paper summarizes the assimilation, absorption, and elimination of these molecules, as well as the impact of processing on their bioavailability

Valorization of Brewers’ Spent Grains: Pretreatments and Fermentation, a Review

Brewers’ spent grains constitute a valuable byproduct of the beer industry. They are characterized by a rich nutritional composition consisting of around 70% lignocellulosic fibrous material, 20% proteins, 10% lipids, in addition to vitamins, minerals, amino acids, and phenolic compounds. These spent grains are produced in large amounts all through the year, are cheap, and lack economically feasible applications. Nowadays, 70% of these spent grains are used as animal feed, 10% are used for biogas production, and the remaining 20% are disposed in landfills. Due to the aforementioned facts, alternative uses of the brewers’ spent grains are highly sought-after. In fact, this nutrient-rich industrial by-product makes it a very good candidate for valorization through biotechnological processing, particularly microbial fermentation. After applying the needed pretreatments, using brewers’ spent grains as a substrate in submerged and solid-state fermentation of different microorganisms leads to the production of various value-added compounds such as organic acids, amino acids, volatile fatty acids, enzymes, vitamins, second-generation biofuels and other products

Optimization of <i>cis</i>-9-Heptadecenoic Acid Production from the Oleaginous Yeast <i>Yarrowia lipolytica</i>

Odd-chain fatty acids (OCFA) have been studied for their therapeutic and nutritional properties, as well as for their potential use in the chemical industry for the production of biofuel. Genetic modification strategies have demonstrated an improved production of OCFA by oleaginous microorganisms. In this study, the production of OCFA-enriched lipids by fermentation using a genetically engineered Yarrowia lipolytica strain was investigated. The major fatty acid produced by this strain was the cis-9-heptadecenoic acid (C17:1). Its biosynthesis was optimized using a design of experiment strategy involving a central composite design. The optimal responses maximizing the cell density (optical density at 600 nm) and the C17:1 content (%) in lipids were found using 52.4 g/L sucrose, 26.9 g/L glycerol, 10.4 g/L sodium acetate, 5 g/L sodium propionate, and 4 g/L yeast extract. Under these conditions, in a 5 L scale bioreactor, the respective contents of lipids and C17:1 in culture medium were 2.52 ± 0.05 and 0.82 ± 0.01 g/L after 96 h fermentation. The results obtained in this work pave the way toward the process upscale of C17:1 and encourage its industrial production

Water-soluble polysaccharides and hemicelluloses from almond gum: Functional and prebiotic properties

International audienceThis paper describes the extraction of polysaccharides (AGP) and hemicelluloses (AGH) from almond gum by hot water and alkaline solution, respectively. Structural and functional properties of the extracted polymers were then determined. For this purpose, infrared spectroscopy was first used to characterize functional groups of both polymers. The molecular weights of AGP and AGH were then determined using high performance size exclusion chromatography, resulting in 5.72×106g/mol and 5.39×106g/mol, respectively. Monosaccharide composition of both polymers was assessed using gas chromatography. The analysis of the functional properties showed that AGP and AGH had high water-holding (11.36g/g and 6.3g/g, respectively) and fat-binding (5.35g/g and 2.7g/g, respectively) capacities, with good emulsion properties. The prebiotic properties of AGP and AGH were then evaluated using in vitro fermentation by Bifidobacterium adolescentis and Lactobacillus acidophilus. Both polymers showed suitability for in vitro fermentation, suggesting thus their prebiotic nature. The obtained results demonstrated the promising potential of AGP and AGH for different applications in food industry