As the Thai Dawk Mali (KDML105) rice variety is popular due to its high sensory after cook, there is an increase in
mixing the KDML105 rice with other rice varieties that leads to unqualified KDML105 milled rice products for export
and unqualified unmilled rice seeds for next plants. Instead of using traditional time consuming methods based on the
disintegration of the rice kernel in an alkali solution and the inspection of rice cooked in boiling water, this paper
proposes to analyze the milled rice powder dissolved in our alkali solution via a spectroscopic method. In our study, 0.1
g, 0.2 g, and 0.3 of milled rice powder from four Thai rice varieties, i.e., KDML105, Pathumthani1, Chainat1, and RD6,
are selected. Then each milled rice sample is ground and then dissolved in a 10% potassium hydroxide (KOH) solution.
At the specified minutes of dissolution, the relative optical transmission spectrum of the milled rice solution in a 500-800
nm wavelength is measured and only its first derivative is used for the identification of the KDML105 milled rice. We
find that the use of 0.10 g of the milled rice powder dissolved in our KOH solution for 10 minutes provides the lowest
false rejection rate of 15%, indicating that we have a faster approach with less amount of waste produced. With the 0.2-g
milled rice powder, 5 minutes of dissolution is needed but with a slightly higher false rejection rate of 18.3%.