Rice flour from four regions and how storage changes it
What it found
After 6 months of storage, rice flour from four Japanese regions had lower rapidly digestible starch and a lower estimated glycemic index.
The flour was tested in the lab, not in people.
What they found
Animal and lab studies
Starch digestibility
Rapidly digestible starch declined significantly in all samples. Changes in slowly digestible starch were insignificant, though regional variations were apparent.
Estimated glycemic index
The estimated glycemic index (eGI) decreased in all samples. Toyama showed the most significant drop, from 136.0 to 125.0.
Other findings
Moisture and protein
After 6 months of storage, moisture content increased across all samples. Crude protein content remained stable, with minor increases.
Lipid and starch
Apparent lipid content increased slightly in the Toyama sample. Total starch content increased in all samples.
Freshness indicators
pH and ΔE showed regional variations. Fukushima had the least degradation and Toyama the most.
What the authors conclude
“Reductions in eGI and the equilibrium concentration of starch hydrolysis after storage suggest that 'Udai21' aged rice flour may produce a slower postprandial glycemic response, likely due to the formation of amylose-lipid or amylose-protein complexes that increase resistance to enzymatic breakdown.”
Also in their conclusions
- They conclude that the regional origin of rice flour influenced its physicochemical properties and starch digestibility significantly.
- They suggest that reductions in eGI and the equilibrium concentration of starch hydrolysis after storage mean that 'Udai21' aged rice flour may produce a slower postprandial glycemic response, likely due to the formation of amylose-lipid or amylose-protein complexes that increase resistance to enzymatic breakdown.
- They say these results highlight the inherent variability in rice flour arising from natural compositional differences driven by environmental factors.
How it was done
The starch digestibility and glycemic responses of rice flour are influenced by intrinsic factors, such as its composition, and extrinsic factors, including storage. This study aimed to examine the impact of extrinsic factors on rice flour production.
They studied rice flour made from the same rice seeds ('Udai21') grown in four production areas: Fukushima, Tochigi, Toyama, and Yamagata prefectures. They stored the flour for 6 months under ambient conditions at 30 °C and measured its starch digestibility and glycemic properties.
What it can’t tell you
- We summarised it from the abstract only.
- This study was done in the lab, not in people, so it cannot show how the flour affects blood sugar in real life.
- It did not measure postprandial glycemic response in people, only estimated it from lab tests.
Who paid
- Funding
- Funded by 57th Leave a Nest Research Grant Suzumo Machinery Award (from the PubMed record).
- Authors work at
- Tokyo University of Agriculture and Technology, Japan; Federal Institute of Industrial Research, Nigeria; Utsunomiya University, Japan
The paper
- Title
- Influence of production area and storage on starch digestibility and glycemic properties of rice flour
- Type
- Study
- Evidence
- Animals and lab studies
- Summarised from
- Abstract only
- Cite
- Nwaeche CF, Saito T, Kitamura R, Tamura M (2026). Influence of production area and storage on starch digestibility and glycemic properties of rice flour. Journal of the science of food and agriculture. doi:10.1002/jsfa.70538PubMed 41794551DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error