New Bioethanol Production Method Increases Food Yield

Oct 12, 2012
Motohiko Hamada, Nikkei Automotive Technology

Japanese researchers developed a "reversed production process" that produces sugar and ethanol in reverse order for the first time in the world.

The new process was developed by researchers of Asahi Group Holdings Ltd and the Kyushu Okinawa Agricultural Research Center of Japan's National Agriculture and Food Research Organization (NARO).

The process enables to produce energy without reducing the amount of food production. What we call "bioethanol that does not compete with food" is produced from an inedible plant. But the process can offer a new type of energy source.

Sugarcane contains two types of sugars. One is sucrose, which is a material for table sugar, and the other is reducing sugar, which cannot be used as a material for table sugar. Reducing sugar also prevents crystallization of sucrose.

Therefore, the researchers developed an yeast that transforms only reducing sugar to ethanol to produce ethanol first and make table sugar with the remaining sucrose later. Traditionally, table sugar is produced first, and ethanol is produced by using its by-product. This time, by reversing the order, it became possible to increase the amount of produced table sugar.

When six sugarcane juices with different densities of reducing sugar were fermented by using the new yeast, sucrose was not decomposed or consumed and almost all of the reducing sugar was consumed to form ethanol in all the juices. More than 90% of the ethanol contained in the fermented juices was recovered in the condensation process of sugar solution, which precedes the crystallization process.

In a crystallization test that followed, it was found that the yield of table sugar drastically increased, compared with the traditional method. Especially, four times more table sugar was recovered from a juice containing an amount of reducing sugar equivalent to the amount contained in a certain kind of sugarcane having a large amount of biomass.