Dehusk Before Parboiling To Reduce Arsenic Levels In Rice

An international team of scientists showed that parboiling wholegrain rice reduced inorganic arsenic levels by 25 percent while more than doubling calcium content of the grains.

AsianScientist (Apr. 30, 2019) – In a study published in the journal Environmental Science & Technology, researchers in Bangladesh and Northern Ireland found that parboiling removes inorganic arsenic from rice while increasing the grains’ calcium content.

Contamination of rice with arsenic is a major problem in some regions of the world with high rice consumption. People in Bangladesh eat about a pound of rice per person per day, according to statistics from the International Rice Research Institute, placing Bangladeshis at risk for elevated exposure to inorganic arsenic.

Researchers in Bangladesh and Northern Ireland wondered whether the method of post-harvest processing of rice would affect the levels of inorganic arsenic in the grains. Typically, most rice in the country is parboiled, a process that involves soaking the rough rice (with husk intact) in water and then boiling it.

The researchers hypothesized that parboiling wholegrain rice (with the husk removed) would reduce the levels of different forms of arsenic compared with parboiling rough rice. The researchers tested their new processing method in 13 traditional, small-scale parboiling plants throughout Bangladesh.

The team used ion chromatography interfaced with inductively coupled plasma-mass spectrometry to analyze arsenic species in rice. They found that in untreated rough rice, inorganic arsenic is highly elevated in the bran compared with the husk, even after parboiling. On the other hand, parboiling wholegrain rice reduced levels of inorganic arsenic by about 25 percent in the final polished grains, while increasing calcium content of the grains by 213 percent.

However, the new method reduced potassium content of the grains by 40 percent. The researchers say that the potassium loss must be balanced against the advantages of reduced arsenic and increased calcium.

The article can be found at: Rahman et al. (2019) Modifying the Parboiling of Rice to Remove Inorganic Arsenic, While Fortifying with Calcium.


Source: American Chemical Society; Photo: Pexels.
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