Xylitol production by fermentation from discarded biomass is one of the most valuable renewable chemicals

Xylitol occurs naturally in small amounts in plums, strawberries, cauliflower, and pumpkin; humans and many other animals make trace amounts during metabolism of carbohydrates.

• Ur-Rehman, S.; Mushtaq, Z.; Zahoor, T.; Jamil, A.; Murtaza, M.A. (2015). “Xylitol: A review on bio-production, application, health benefits, and related safety issues”. Critical Reviews in Food Science and Nutrition. 55 (11): 1514–1528. doi:10.1080/10408398.2012.702288. PMID 24915309. S2CID 20359589.

Unlike most sugar alcohols, xylitol is achiral.

• Wrolstad, Ronald E. (2012). Food Carbohydrate Chemistry. John Wiley & Sons. p. 176. ISBN 9780813826653. Retrieved 20 October 2012 – via Google Books.

Most other isomers of pentane-1,2,3,4,5-pentol are chiral, but xylitol has a plane of symmetry.

Industrial production starts with lignocellulosic biomass from which xylan is extracted; raw biomass materials include hardwoods, softwoods, and agricultural waste from processing maize, wheat, or rice. The xylan polymers can be hydrolyzed into xylose, which is catalytically hydrogenated into xylitol. The conversion changes the sugar (xylose, an aldehyde) into the primary alcohol, xylitol. Impurities are then removed.

• Ur-Rehman, S.; Mushtaq, Z.; Zahoor, T.; Jamil, A.; Murtaza, M.A. (2015). “Xylitol: A review on bio-production, application, health benefits, and related safety issues”. Critical Reviews in Food Science and Nutrition. 55 (11): 1514–1528. doi:10.1080/10408398.2012.702288. PMID 24915309. S2CID 20359589.

The mixture is often processed by standard industrial methods; industrial fermentation involving bacteria, fungi, or yeast, especially Candida tropicalis, are common, but are not as efficient.

• Ur-Rehman, S.; Mushtaq, Z.; Zahoor, T.; Jamil, A.; Murtaza, M.A. (2015). “Xylitol: A review on bio-production, application, health benefits, and related safety issues”. Critical Reviews in Food Science and Nutrition. 55 (11): 1514–1528. doi:10.1080/10408398.2012.702288. PMID 24915309. S2CID 20359589.
• Jain, H.; Mulay, S. (March 2014). “A review on different modes and methods for yielding a pentose sugar: Xylitol”. International Journal of Food Sciences and Nutrition. 65 (2): 135–143. doi:10.3109/09637486.2013.845651. PMID 24160912. S2CID 39929588.

According to the US Department of Energy, xylitol production by fermentation from discarded biomass is one of the most valuable renewable chemicals for commerce, forecast to be a US$1.4 billion industry by 2025.

• Felipe Hernández-Pérez, Andrés; de Arruda, Priscila Vaz; Sene, Luciane; da Silva, Silvio Silvério; Kumar Chandel, Anuj; de Almeida Felipe, Maria das Graças (16 July 2019). “Xylitol bioproduction: State-of-the-art, industrial paradigm shift, and opportunities for integrated biorefineries”. Critical Reviews in Biotechnology. 39 (7): 924–943. doi:10.1080/07388551.2019.1640658. ISSN 0738-8551. PMID 31311338. S2CID 197421362.