IIT-G develops new method to produce sugar substitute ‘Xylitol’ from sugarcane waste

Overcomes limitations of chemical methods of synthesis & time delays associated with conventional fermentation

 Indian Institute of Technology Guwahati (IIT-G) researchers have developed an ultrasound-assisted fermentation method to produce a safe sugar substitute called ‘Xylitol’ from sugarcane bagasse (the residue left after crushing of sugar cane). This method overcomes the operational limitations of chemical methods of synthesis and the time delays associated with conventional fermentation.

With increasing awareness of the adverse effects of white sugar (sucrose), not only for patients with diabetes but also for general health, there has been a rise in the consumption of safe alternative sweeteners. Xylitol, a sugar alcohol derived from natural products, has potential anti-diabetic and anti-obesogenic effects, is a mild prebiotic and protects teeth against caries.

The researchers first hydrolysed the hemicellulose in bagasse into five carbon (pentose) sugars such as xylose and arabinose.  For this, they chopped the bagasse into small pieces and treated them with dilute acid. The sugar solution was then concentrated and a form of yeast called Candida tropicalis was added to this to bring about fermentation.

Without ultrasound, only 0.53g xylitol was produced per gram of xylose, but on subjecting the process to ultrasound, the yield was 0.61g/gram of xylose.  This number translates to 170 g of xylitol per kilogram of bagasse. The yield could be further increased to 0.66g/gram of xylose and the fermentation time reduced to 15 hours by immobilising the yeast in polyurethane foam.

“The present research has been carried out on laboratory scale. Commercial implementation of sonic fermentation requires the design of high power sources of ultrasound for large-scale fermenters, which in turn requires large-scale transducers and RF amplifiers, which remains a major technical challenge” said Prof V.S. Moholkar, Department of Chemical Engineering, IIT Guwahati.

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