Thailand’s Rice Science Centre has asked the government to review its plan to sell decade-old rice from the infamous rice pledging scheme and to allow researchers to analyse the grain to ensure consumer safety.
The centre cited a commentary by Professor Dr. Apichart Vanavichit, former director of the centre at Kasetsart University, and his staff, regarding the old rice and the issues to be considered before the rice is consumed by humans.
According to the opinion piece, the first consideration is how well the rice has been stored. It must have been stored in a cold and dry facility, away from sunlight and humidity. To maintain the quality in prolonged storage, the rice must also be stored where there is minimum oxygen.
Another consideration is that the rice must be checked for signs of degradation, such as a change in the colour, unusual smell, rice weevils or fungi. Rice which is kept for a long time will also lose its nutritional value, even though it might still be safe for consumption.
The third consideration are the multiple fumigations to which the rice has been exposed, which may pose a risk of chemical residues, such as methyl bromide and aluminium phosphide. Old rice may also contain toxins produced by fungi, such as aflatoxin and ochratoxin A, which are carcinogenic.
Grain which is kept for a long time may oxidise, resulting in residues called phosphorus-oxyacids and orthophosphate. These substances cannot be eradicated using heat or air circulation.
When aluminium phosphide (AIP) comes into contact with water, it will produce hydrogen phosphine (PH3), which can be absorbed through the stomach, leading to nausea, breathing difficulties and, in extreme cases, death.
