Effects of Brown Seed Coat Retention and Thermal Processing on Nutritional Composition, Bioactive Compounds, Antioxidant Activity, and Functional Properties of Jackfruit Seed Flour

Jackfruit seed is an underutilized by-product with potential as a functional ingredient. This study investigated how brown seed coat retention and thermal processing affect the color, nutritional composition, β-glucan content, bioactive profiles, antioxidant activity, and functional properties of jackfruit seed flour. Seeds were processed as raw, boiled, or steamed samples, with or without the brown seed coat retained, using rice and wheat flours as references. Brown seed coat retention reduced lightness and increased redness. Jackfruit seed flour generally showed higher ash, protein, and fiber contents than reference flours, while seed coat retention further enhanced fiber content. β-glucan content ranged from 56.11 to 286.71 mg/g. Brown seed coat samples showed the highest TPC, TFC, and antioxidant activity, followed by brown seed coat-retained flour samples. Thermal processing reduced bioactive compounds and antioxidant activity; however, steaming better retained bioactive compounds, antioxidant activity, and β-glucan content in brown seed coat-retained flour than boiling. Heatmap analysis revealed cinnamic acid, gentisic acid, myricetin, and quercetin as major compounds. Functional analysis showed higher WSI and WHC than reference flours, while OHC and WSC were generally comparable. These findings suggest the potential of brown seed coat-retained jackfruit seed flour for further development as a functional ingredient.