Capital Rice, Thailand's leading organic rice producer and distributor, has teamed with the National Innovation Agency (NIA) and Siam Waterflame Co in adopting a system in which nitrogen is used to eradicate weevils in grain.
Science and Technology Minister Peeraphan Palusuk (centre) join rice executives in testing the technology to use nitrogen to kill rice weevils. SOMCHAI POOMLARD
The system will replace the existing method in which carbon dioxide is used in the vacuum packing process.
The new method is considered safe for consumers and will keep organic rice free from any chemicals.
"Using nitrogen will significantly help to reduce time and expense in eradicating the insects," said deputy managing director Wanlop Pichpongsa.
Insects such as weevils multiply rapidly, especially on chemical-free rice. Lengthy storage will see the insects breed. If rice is stored for about three months, the average number of weevils is 23 per kilogramme but would likely be significantly higher if rice is kept longer.
For regular rice, methyl bromide gas is applied to fumigate the grain when stockpiled. This gas is the most inexpensive, costing only 2-5 baht a tonne and effective in killing the insects, even their eggs and cocoons.
However, Thailand will ban the gas in 2015, joining 177 other countries, in order to reduce ozone layer depletion. Some developed countries stopped using methyl bromide in 2005.
Samrit Jeang, the managing director of Siam Waterflame, said many rice firms back then turned to phosphine, which was also cheap at 12 baht a tonne of rice and could get rid of weevils after 5-7 days of fumigation.
For organic rice, carbon dioxide is pumped into containers to weaken and kill the insects. The method costs about 110 baht/tonne and takes as long as 15 days to kill weevils.
With the new method, oxygen levels in a container will be reduced to 0.5% with nitrogen taking up the rest. Normal air consists of 21% oxygen, 78% nitrogen and 1% of other gases.
"The insects and eggs are eradicated within a week," Mr Samrit said.
It is also a cheap process, as the cost of the gas is about 10 baht per tonne of rice.
The system has been tested over the past two years and monitored by the Agriculture Department.
The NIA has also provided financial backing for the new system as part of its attempts to promote innovation in rice cultivation and the production and export of organic rice.
Thailand produced about 69,000 tonnes of organic rice last year, of which 6,000 tonnes were exported for 243 million baht.