A High-Throughput In Vitro Assay for Screening Rice Starch Digestibility

Area of Science:

• Agricultural Science
• Biochemistry
• Food Science

Background:

• Rising global obesity and chronic diseases necessitate dietary interventions, including the development of low-glycemic index (GI) foods.
• Rice is a staple food, but its rapid digestion can lead to adverse health outcomes.
• Current rice breeding programs lack efficient methods to identify varieties with slow starch digestion.

Purpose of the Study:

• To develop a high-throughput in vitro assay for screening cooked white rice digestibility.
• To evaluate the assay's efficacy in differentiating rice genotypes based on starch hydrolysis rates.

Main Methods:

• An in vitro digestion assay was developed and optimized.
• Cooked white rice grains from different genotypes were subjected to the assay.
• Starch hydrolysis was measured at a specific time point (SH-60) to assess digestibility.

Main Results:

• The assay successfully differentiated the digestibility rates of three commercial rice genotypes (Doongara, Reiziq, Waxy).
• Further testing on eight genotypes confirmed that SH-60 values effectively distinguished low-digestibility (50-59%) from intermediate/high-digestibility (64-93%) rice.
• Doongara and YRL127 showed significantly lower starch hydrolysis at 60 minutes.

Conclusions:

• A novel high-throughput in vitro assay can accurately screen rice for slow starch digestibility.
• This method can significantly aid rice breeding programs in developing varieties with improved postprandial glycemic responses.
• Application of this assay can contribute to public health by facilitating the creation of healthier rice options.