Cheaper production of Xylitol

XYLITOL, a white, crystalline sugar substitute, is a naturally occurring carbohydrate sweetener classified amongst the sugar alcohols or polyols. While sorbitol dominates the global polyols market, Xylitol comes second in terms of production.  Xylitol and Sorbitol have similar end uses. However, Xylitol is priced far higher than Sorbitol due to greater costs of production. In the wake of increasing Xylitol demand owing to perceived health benefits, research has been conducted to ascertain the possible development of a cost effective method for production. This article thus reviews the feasibility of two suggested alternatives to conventional Xylitol production – use of switchgrass and sugarcane bagasse as feedstock.

Using sugarcane bagasse as feedstock can lower production costs of Xylitol

The global sweetener and sugar substitute market, of which Xylitol and Sorbitol occupy a significant share, is expected to grow at a CAGR of 4.5% to a value of US$13.7 billion by 2018. While Sorbitol dominates the global polyols market, Xylitol comes second, and accounts for a 14.9% share of the market and 2013 production estimate of 223,950 MT. 

The issue

Xylitol is produced from both wood and corn-cob. It is manufactured by Chinese suppliers from corn-cob, while other suppliers mainly manufacture Xylitol from wood. The price of wood Xylitol is estimated at around 12,000 USD/MT which is very expensive owing to high feedstock prices. The price of Chinese corncob Xylitol is around 3,200 USD/MT. While the latter is cheaper, this is still higher than Sorbitol prices which are around 750-850 USD/MT in both the US and China.

Xylitol and Sorbitol are substitutes utilized by the chewing gum industry and pharmaceuticals. Considering that there is a growing demand for Xylitol due to its perceived health benefits, there will be pressure on the part of procurement companies to choose it over Sorbitol. This could lead to higher annual spending unless alternate cost effective ways of Xylitol production is introduced, to bring the prices down.

Two papers have been published on alternate cost-effective methods of Xylitol production. This article reviews these methods and determines which one is the most feasible in the context of Xylitol procurement. This may help indicate the future direction of the Xylitol supplier market.

Proposed alternatives to conventional Xylitol production

Method 1 – Use of switchgrass as feedstock:  The first method is suggested by Neeru et al. (2013) in “Biological production of Xylitol from corn husk and switchgrass”. Xylitol was produced by biological reduction using Yeast strain Pichia stiptis CBS 5773 after extracting xylose from hemicellulose raw materials like corn husk and switchgrass. The authors noted that the bioconversion pathway appears to be an effective alternative for Xylitol production. Using raw materials like switchgrass with high xylose content will reduce production costs.

Method 2 – Use of sugarcane bagasse as feedstock: The second method is suggested by Canilha et al. (2013) in “Bioconversion of Hemicellulose from Sugarcane Biomass into Sustainable Products”. The authors opine that hemicellulose fractions of sugarcane bagasse can be utilized to produce Xylitol employing microbes like Pichia, Candida and Debaromyces with good yields.

Feasibility analysis of proposed methods for Xylitol production

Feasibility analysis of method 1: Neeru et. al (2013) propose the production of Xylitol using switchgrass as substrate. But there are certain disadvantages in that switchgrass is bulky, making it cumbersome to transport. Hence, production costs may not be reduced by a large margin. Furthermore, Knoxville news reports that in Loudon County, DuPont, one of the major wood Xylitol manufacturers, had given contracts to switchgrass farmers in partnership with Genera Energy, a private company created by the University of Tennessee Research Foundation to build a test production facility. However, as of 2013, four of 61 contracted farmers have pulled out of the switchgrass production. So, investigation on the use of switchgrass feedstock has stagnated and is not likely to progress greatly in the near future.

Feasibility analysis of method 2: Canilha et al. (2013) recommends sugacane bagasse as alternate feedstock. This method seems to be the most feasible since yield of Xylitol from sugarcane bagasse is 23.1%, which is comparable to the yields of corncob (21.6%) and wood (21.9%). Sugarcane bagasse is a waste product like corncob. Hence, it is possible that cost of production will be as cheap as that of corncob Xylitol.

Conclusion

There is tremendous potential for the production of Xylitol from sugarcane bagasse. India and Brazil are the major producers of bagasse. Comparable yields of Xylitol with wood and corncob, possibility of integrating Xylitol production with biofuel production and abundant availability of bagasse feedstock could see India and Brazil emerging as potential suppliers of Xylitol a decade from now. Hence, the method suggested by Canilha et al. (2013), ie, using sugarcane bagasse as feedstock, is more feasible.

*Govindarajan Parthasarathy is research analyst – crops at Beroe Inc.