Valorization of brown alga Saccharina japonica holdfasts using subcritical water hydrolysis and it's application for functional rice enhanced α-glucosidase inhibitory activity

This study focused on the valorization of the roots of Saccharina japonica (brown algae) using subcritical water extraction (SSE) and hot water extraction (SHW). The quantities of bioactive compounds from both extracts were also analyzed. The antioxidant and α-glucosidase inhibitory activities of these extracts were evaluated under various extraction conditions. The IC₅₀ value for the SSE extract ranged from 0.81 to 8.80 mg/mL, indicating its potential biological activity. The extracts were then applied to functional rice to reduce its glycemic index. The fortification process extended the hydrolysis time of the functional rice, leading to an increase in slowly digestible starch and resistant starch compared to the control sample. As a result, the hydrolysis index of the functional rice decreased to 43.73 %, while the control sample (instant rice) had a hydrolysis index of 99.80 %. The findings of this work suggest that SSE and SHW techniques can be effectively employed in the production of functional rice with a lower glycemic index. This could appeal to health-conscious consumers, offering a nutritious alternative to traditional rice products.