Abstract— This study aimed to quantify flavonoids and polyphenols among 10 different rice varieties, ranging from white to brown rice, and to describe gene expression profiles related to their biosynthesis. The study analyzed the total phenolic content (TPC), total flavonoid content (TFC), and total anthocyanin content (TAC) of 10 rice varieties at HATRI.

The results showed that the TPC of brown and white rice from different varieties differed significantly (p < 0.05). The measured TPC in brown rice was significantly higher (118.98–206.06%) than in white rice. The highest TPC in brown rice was found in black rice (771.15 mg/100 g).

The TFC of brown and white rice from different varieties also differed significantly. The TFC of brown rice ranged from 178.74 to 526.65 mg/100 g, while that of white rice ranged from 85.41 to 432.15 mg/100 g. Brown rice had a 10%–20% higher total flavonoid content than white rice. However, the difference between brown and white rice was smaller in the OM5451 and HATRI 722 varieties.

The content of free and bound anthocyanins in the rice fractions of ten different genotypes ranged from 15.32 to 183.05 mg and from 6.18 to 24.16 mg Cy3-GE/100 g DM, respectively. The highest anthocyanin concentrations were found in the free form. Black rice (HATRI 40) showed the highest anthocyanin content (234.62 mg Cy3-GE/100 g DM), followed by the HATRI 11 variety (73.88 mg Cy3-GE/100 g DM) and white rice (50.42 mg Cy3-GE/100 g DM).

This study enriches the understanding of bioactive compounds in rice and provides a solid foundation for improving these compounds in functional rice products in Vietnam.

 

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