Testing the Genetic Purity of Riceberry Rice

Riceberry: the name is the cause. Before it was ‘Hom Nin’, now ‘Riceberry’

Riceberry is a pure hybrid of Khao Dawk Mali 105 and Hom Nin non-glutinous rice, born with such deliciousness that people forget they are eating brown rice, which has set off a fight over the ‘name’. Today there are black rice varieties like Riceberry, namely Hom Nin (the male parent), Sukhothai black rice, Surin black jasmine rice (Surin Rice Research Center) and so on.

Genetic purity testing of 10 Riceberry samples on the market by the DNA Technology Laboratory, Kasetsart University, found that only 5 samples were Riceberry with purity of 95% or more, while the samples that failed the standard had other rice varieties mixed in at 6–100%. If more samples were randomly tested, a greater variety of adulteration would likely be found.

Figure 1: Example of testing Riceberry for adulteration, finding that 5 of the 10 samples passed the criterion (purity equal to or greater than 95%). The black non-glutinous rice most often mixed into Riceberry is mostly Hom Nin.

To give consumers confidence in choosing high-nutrition organic rice and rice products, there is an ongoing market research project to develop a quality certification mark for high-nutrition organic rice called Thanyaosot, or Rice ‘O’ Sod. Products receiving this quality mark must be controlled in production from paddy in farmers' fields to bagged rice reaching consumers. The Thanyaosot quality mark has now been registered as a series trademark at the Department of Intellectual Property, Ministry of Commerce. The measures required of products bearing the Thanyaosot standard mark are: 1) the rice is grown by certified organic farming; 2) rice genetic purity of more than 95%; 3) primary processing measures, from a mill that meets GMP standards and is tested for contamination by microorganisms, toxins and heavy metals; 4) packaging measures, requiring the packing room to meet HACCP standards; 5) nutritional value must be checked regularly and the label on the rice bag kept as current as possible.

Figure 2: Trademark registered with the Trademark Office, Department of Intellectual Property, Ministry of Commerce

Testing rice genetic purity

As for rice genetic purity, the ‘Thanyaosot’ standard requires that rice certified as Riceberry have genetic purity equal to or greater than 95%, with rice samples sent for genetic analysis according to the standard of the DNA Technology Laboratory, Kasetsart University, Kamphaeng Saen Campus.

Approach to developing rapid adulteration testing methods

So that there is a laboratory able to provide rice DNA identity testing services specifically for the Bureau of Commodity Standards, Department of Foreign Trade, as a reference lab, Kasetsart University saw fit to establish a laboratory for analyzing the DNA identity of Thai rice to test the purity of Thai rice for export and to trace fragrant rice from neighboring countries that may compete with Hom Mali rice. The laboratory operates as a “project under cooperation between the Department of Foreign Trade and Kasetsart University”. In the future Riceberry will likely be an important export rice in the rapidly expanding health market, so a method for testing Riceberry adulteration has also been developed.

Method

1. Survey and group the cultivated rice with potential to be mixed with Riceberry into groups by outstanding traits, namely color, grain size, photoperiod sensitivity and so on
2. Search for genetic codes unique to the rice of each group, starting from the existing DNA identity database of the DNATEC laboratory, searching research for the genetic codes of these rice varieties, and searching for the DNA codes of target genes likely to distinguish varieties 
3. Search for suitable analysis technology that lowers cost and handles more samples quickly and accurately, improving from the DNA extraction step, the polymerase chain reaction (PCR) and analysis, with greater emphasis on automation
4. Design a new laboratory to match the new technology being developed until the best method meeting the target is obtained