Bio-active compounds, their antioxidant activities, and the physicochemical and pasting properties of both pigmented and non-pigmented fermented de-husked rice flour

The aim of this study was to determine the effect of both the Solid State Fermentation (SSF) technique and the use of Rhizopus oligosporus on the physicochemical changes of fermented de-husked rice flour. Three varieties of de-husked rice, i.e., Mentik Wangi Susu (non-pigmented), red Cempo Merah, and black Jowo Melik (pigmented) were fermented using Rhizopus oligosporus. Fermentation was performed at room temperature with a fermentation time of 0, 24, 48, and 72 hours. The analyzed parameters were proximate composition, bio-active compounds, and pasting profile. The results showed an increase in flour pasting profile, ash, protein, and fat content after the fermentation. The total availability of the total phenolic content (TPC) and antioxidant capacity were also increased. The highest TPC (0.37 mg GAE/g) and antioxidant capacity (1.43 mg TEAC/g) were obtained in the Jowo Melik variety at 72 hours of fermentation. In contrast, anthocyanin and carbohydrate contents decreased as fermentation time increased. The highest anthocyanin content of 0.53 mg/g (after 24-hour fermentation) was obtained in the Jowo Melik variety. In conclusion, 72-hour-fermented black rice flour (Jowo Melik) has a higher potential to be developed as a functional food.