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Prospects of Utilization of Various Solid Agro Wastes for Making Value Added Products for Sustainable Development
Published in Gunjan Mukherjee, Sunny Dhiman, Waste Management, 2023
J. Sharon Mano Pappu, Sathyanarayana N. Gummadi
Xylitol (C5H12O5), a five-carbon polyol with a molecular weight – 152.15 g mol–1, is considered as a naturally occurring polyalcohol in which each carbon atom in its chain has a hydroxyl group attached to it. The major characteristic of xylitol is its sweetening capacity comparable to sucrose while exhibiting one-third of calories lesser than that of sucrose (10 for xylitol vs. 16 J g–1 for sucrose) (Nayak et al. 2014). Another benefit of xylitol is its high endothermic heat (145 J g–1) which presents a cooling effect after ingestion (Mussatto and Roberto 2003). Xylitol, a sugar alcohol, can be readily applied in food industries as it does not affect the nutritional value of protein as it is not involved in Maillard reaction.
Nanocatalysts from Biomass and for the Transformation of Biomass
Published in Vanesa Calvino-Casilda, Antonio José López-Peinado, Rosa María Martín-Aranda, Elena Pérez-Mayoral, Nanocatalysis, 2019
The second most abundant carbohydrate after D-glucose, xylose, can be hydrogenated to produce xylitol, which is employed in food, cosmetic and pharmaceutical industries. Similar to the case of glucose, Raney-type nickel catalysts have been used industrially for the hydrogenation of xylose; however, they suffer from deactivation, produced by leaching and surface poisoning. As a consequence, other alternative catalysts have been tested in the reaction. Some examples are Ru/SiO2 and Ru/ZrO2, affording a 99.9% yield to xylitol and a 1 wt % Ru/(5 wt % NiO−TiO2) catalyst, with a yield of 99.7%. Pt NPs (1.3 nm) on MWCNTs were also used for the hydrogenation of xylose to xylitol with 100% conversion of xylose and 99.3% selectivity to xylitol, compared to commercial Pt/C, Ru/C and Raney Ni catalysts (Nakagawa and Tomishige 2010).
Biodegradation of Hemicelluloses
Published in Jean-Luc Wertz, Magali Deleu, Séverine Coppée, Aurore Richel, Hemicelluloses and Lignin in Biorefineries, 2017
Jean-Luc Wertz, Magali Deleu, Séverine Coppée, Aurore Richel
As substrates, hemicelluloses are readily available for the production of value-added products such as bioethanol, xylitol, lactic acid, and 2,3-butanediol.5,6 Xylitol is commonly used as a sweetener; lactic acid is used as a monomer for PLA (polylactic acid); and 2,3-butanediol as a precursor for the manufacture of a range of chemical products such as methyl ethyl ketone, gamma-butyrolactone, and 1,3-butadiene.7 Xylitol can be produced either by chemical synthesis or by fermentation. Industrially, it is produced by catalytic hydrogenation of xylose.8 Intensive research efforts in the last 25 years have led the way for the successful conversion of hemicelluloses into fermentable constituents by pretreatment technologies and engineered hemicellulases. A major challenge is the isolation of microbes with the ability to ferment a broad range of sugars and withstand fermentative inhibitors that are usually present in hemicellulosic sugar syrup.
Improved xylitol production by the novel inhibitor-tolerant yeast Candida tropicalis K2
Published in Environmental Technology, 2022
Anup Kumar Singh, Ajay Kumar Pandey, Mohit Kumar, Tanushree Paul, Naseem A. Gaur
Xylitol, a naturally occurring polyalcohol, has a similar sweetness as table sugar with 40% less calorie content (2.4 cal/g for xylitol vs. 4 cal/g for sucrose) [8]. Xylitol has wide application in various industries, such as pharmaceuticals, nutraceuticals, food and beverage etc., thus counted as one of the various high-rated global bio-products in an expeditiously growing global market, which is further expected to cross nearly USD 1.37 billion by 2025 [9]. Although several artificial sweeteners are available in the market (acesulfame potassium, etc.), xylitol has added benefits in terms of its ability to reduce cavities and strengthen tooth enamel [10]. Currently, most of the xylitol available in the market is produced through a chemical conversion process wherein D-xylose is converted to xylitol under elevated temperature and pressure with the help of a nickel catalyst. This method is cost-intensive, generates hazardous materials and carries a potential risk of contamination [11]. In this regard, xylitol production via the microbial route is very attractive and significant.
Bioconversion study for xylitol and ethanol production by Debaryomyces hansenii: aeration, medium and substrate composition influence
Published in Preparative Biochemistry & Biotechnology, 2022
Soledad Mateo, Gassan Hodaifa, Sebastián Sánchez, Alberto J. Moya
Several yeasts have been used to obtain current products of interest by microbiological processes. In this sense, xylitol could be considered as natural sugar alcohol[1] with aggregated-value and interesting properties for products applications[2] and enormous benefits for health. It can be used as a diabetic sweetener since its metabolism does not require insulin intake.[3] Otherwise, xylitol owns a considerable anti-cariogenic power because of not being employed by a microorganism of oral flora; it avoids acids generation that could attack the dental enamel.[4] Apart from that, it has advantageous sweetening properties similar to sucrose[5] and fair low caloric content. For all these reasons, xylitol has currently a wide range of applications: bakery products, jams, jellies, chewing gum, pharmaceutical and oral hygiene products as well as for chemical polymer synthesis. Theoretically, xylitol obtainment could be carried out by natural extraction from specific foods,[6] catalytic hydrogenation methods from commercial D-xylose or fermentation processes using microorganisms. The biological production route appears as a consequence of different alternative researches to solve some of the drawbacks of chemical synthesis by reducing routines, such as both high pressures and temperatures as well as the high cost of catalytic processes.
Improvement of enzymatic bioxylitol production from sawdust hemicellulose: optimization of parameters
Published in Preparative Biochemistry & Biotechnology, 2021
Islam S. M. Rafiqul, Abdul Munaim Mimi Sakinah, Abdul Wahid Zularisam
Worldwide xylitol is industrially manufactured by a chemical hydrogenation of pure xylose obtained from hard woods and agri-residues.[4,6–8] However, the high production cost of this method and the necessity to minimize the environmental impact, caused by the use of toxic nickel catalyst, and high temperature and pressure, have led to extensive exploration of alternative routes for producing xylitol. Microbiological xylitol production from LCBs has been extensively investigated as an alternative to the chemical route.[9–12] The advantages of the fermentation process over chemical ways are its cheaper production cost due to the non-necessity of extensive xylose purification and low environmental impact.[4,10] The application of this process on an industrial level is time-consuming, being associated with some preparatory activities like sterilization and regular inoculum development involving input of energy, labor, and time, leading to decreased productivity.[4,11] The chemical process has a yield of about 80% of the initial xylose,[6,7] and for the microbial fermentation route, 65–85% of yield has been reported.[4,7,13,14] However, the lower xylitol bioconversion rate and downstream processing problem are still a challenge to establish a feasible, low-cost, and large-scale technology.