Development and Evaluation of Gluten-Free Rice Biscuits: Impact on Glycaemic Index and Bioactive Compounds

Biscuits are widely consumed snacks traditionally made from wheat flour, which poses challenges for individuals with gluten intolerance and/or diabetes due to their high glycaemic index (GI). This study explored the production of gluten-free biscuits using rice flour from two varieties, Type III (Basmati) and Ariete (Long A), incorporating varying proportions of rice bran as a substitute for milled and brown rice flour. Results show that biscuits made with rice bran had lower starch digestibility and reduced GI (57.06-62.75) compared to control biscuits (66.23-66.95). Rice bran also increased bioactive compounds, such as phytic acid (0.16 to 1.96 g/100 g), γ-oryzanol (0.20 to 86.56 mg/100 g), and γ-aminobutyric acid (6.78 to 16.23 mg/100 g), known for their benefits to diabetes metabolism. Physicochemical analysis further revealed higher protein (6.49%) and lower starch content (30.07%) in rice bran biscuits than in control biscuits (4.20% and 47.38%, respectively). The control biscuits exhibited the highest spread ratio (5.90 and 6.35) and the Ariete variety produced less brittle biscuits (168.30 N), although the addition of bran increased brittleness under cutting force (54.55 N). Sensory evaluation of four rice biscuit formulations showed no significant differences in consumer preferences, regardless of flour type, bran proportion, or rice variety. Among the formulations, the Type III biscuits with an equal blend of milled flour and rice bran stood out, offering improved nutritional quality and a promising option for gluten-free, low-GI diets for consumers seeking healthier alternatives. This formulation also proved a strong balance across key nutritional and bioactive parameters, when compared to a commercial wellness biscuit.