Physical and Chemical Properties of Gluten-Free Biscuits Incorporated With Purple Sweet Potato Flour

Gluten-free products have gained increased attention due to the growing prevalence of gluten sensitivity and celiac disease. This study is aimed at developing gluten-free biscuits by replacing corn flour (CF) with purple sweet potato flour (PSPF) at levels of 0%-50% and at investigating the effects on physical properties, bioactive compounds, antioxidant activity, nutritional composition, and sensory evaluation. The results showed that increasing PSPF significantly enhanced (p < 0.05) the levels of bioactive compounds and antioxidant activity. The PSPF50 sample exhibited the highest total phenolic content (302.58 μg GAE/g dw) and flavonoid content (974.86 μg QE/g dw), compared to the control sample, which contained only 5.34 μg GAE/g dw and 27.78 μg QE/g dw. The antioxidant inhibition activities of 84.08% (DPPH) and 93.39% (ABTS) at 0.5 mg/mL represented 3.7-fold and 3.8-fold increases over the control. PSPF50 also showed higher protein content (2.20%) and dietary fiber (4.43%) than the control sample (0.32% and 0.52%, respectively). Significant changes were also observed in the spread ratio (8.82-12.02) and the density (0.86-1.54 g/cm³). Sensory evaluation indicated that the PSPF30 sample received the highest scores for all attributes, with ratings in the excellent range. Both lower and higher substitution levels led to a significant decline in acceptance (p < 0.05). In conclusion, PSPF enhances both the nutritional and functional properties of gluten-free biscuits. Substituting 30% PSPF was found to provide the best balance of sensory quality and industrial applicability.