Comprehensive evaluation of purine removal and nutritional quality of adzuki beans by acid-assisted hydrothermal treatment

Adzuki beans are rich in nutrients but high in purines, limiting their intake for patients with hyperuricemia. This study employed acid-assisted hydrothermal treatment (AHT) to remove purines from adzuki beans. The lower purine contents were found in adzuki bean treated with hydrochloric acid (37.72 mg/100 g), phosphoric acid (42.22 mg/100 g), and citric acid (68.75 mg/100 g), representing removal rates of 72.26%, 70.43%, and 49.45% respectively, while their processing losses were acceptable. Furthermore, low-purine adzuki bean powder exhibited lower purine release rate during in vitro digestion. AHT has improved the purine adsorption capacity of insoluble dietary fiber and enhanced the inhibitory effect of polyphenols on xanthine oxidase in adzuki beans. It also reduces the glycemic index of starch and improves protein digestibility in these beans. These enhancements have direct or potential therapeutic effects for treating hyperuricemia. Overall, AHT represents an effective approach for the processing of low-purine adzuki bean powder.