Cellulose might be suitable for making the eco-friendly fuel, bioethanol, report scientists in Japan. 

Cellulose, a fibre found in all plant material, is the most abundant biomass in the world. But researchers say its resistance against chemical and enzymatic hydrolysis and its insolubility in most solvents has so far limited its use as a source of biofuel. 

Shigeru Deguchi of the Japan Agency for Marine-Earth Science and Technology, Yokosuka, and colleagues have now discovered that cellulose can form a gel, just like starch, which is commonly used in biofuel production. The researchers found that cellulose undergoes a transformation from a crystalline form to an amorphous gel-like one, in water at high temperature and pressure. 

Starch forms a gel when heated in water to around 70 degrees Celsius. This process is illustrated by the changes seen when cooking starchy foods like pasta. Gelatinisation is a key step for converting starch into glucose, which can then be fermented to make bioethanol. Until now it had been thought that cellulose could not gelatinise, because its crystalline structure is more stable than starch. 

Vic Morris, from the Institute of Food Research, Norwich, UK, said Deguchi's findings could lead to new ways of using cellulose as a carbon source for fermentation. 'In this context it would be interesting to see whether similar transitions are observed in the less-pure preparations present in biomass,' said Morris. 

Deguchi added, 'a trick has to be found to induce the transformation at milder conditions before the finding leads to actual application.' 

Sarah Corcoran