Combined effects of germination and parboiling on the nutrient bioavailability and glycemic index of selected indica rice varieties
Abstract The study examines the combined effects of germination and parboiling on starch digestibility, nutrient bioavailability, and glycemic index (GI) of five commercially significant South Indian Indica rice varieties: Pokkali, Kuruva, Kattuyanam, Jyothi, and Uma. The research assesses changes i...
Saved in:
| Main Authors: | , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Nature Portfolio
2025-07-01
|
| Series: | Scientific Reports |
| Subjects: | |
| Online Access: | https://doi.org/10.1038/s41598-025-97165-2 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| Summary: | Abstract The study examines the combined effects of germination and parboiling on starch digestibility, nutrient bioavailability, and glycemic index (GI) of five commercially significant South Indian Indica rice varieties: Pokkali, Kuruva, Kattuyanam, Jyothi, and Uma. The research assesses changes in the content of phenolics, flavonoids, and gamma-aminobutyric acid (GABA) induced by germination, followed by parboiling. Rice samples were subjected to various germination periods prior to parboiling, and their nutritional profiles and GI values were compared with those of rice that subjected to parboiling alone. The predicted GI was validated through oral glucose tolerance tests (OGTT) to measure physiological glycemic responses (SL-06/2023 and SL-07/2023 dated 11/01/2023). Additionally, C-peptide levels were assessed in healthy volunteers to further evaluate the antidiabetic potential. Results indicate that germination combined with parboiling significantly improved the phytochemical profiles of the rice varieties. The total phenolic content (TPC) was highest in the 48-hour germinated-parboiled Kattuyanam rice (224.0 mg GAE/100 g, p < 0.05), while other varieties also showed increased TPC after 48 h of germination. The total flavonoid content (TFC) and GABA were also elevated in the 48-hour germinated-parboiled Kattuyanam rice (590 mg QE/100 g and 513.2 mg/100 g, p < 0.05, respectively). All germinated-parboiled samples exhibited lower GI values, with Pokkali showing the lowest predicted GI (41.7). In vivo GI measurements validated the in vitro results, underscoring the benefits of germination before parboiling in enhancing nutrient bioavailability, starch digestibility, and reducing GI. These findings suggest that the combined germination and parboiling process could be an effective dietary intervention for glycemic control in type 2 diabetes management, highlighting its potential for improved nutritional and medicinal applications in rice. |
|---|---|
| ISSN: | 2045-2322 |