The addition of tiger nut by-product improved the physical, nutritional and safety quality of gluten-free cookies

Abstract

The purpose of this study is to investigate the quality attributes of gluten-free cookies from sorghum flour and tiger nut pomace (TNP). Flour blends containing sorghum and TNP at 0, 5, 10, 15 and 20% were evaluated for functional and dough textural properties, while the cookies were evaluated for proximate, physical, bioactive, microbial storage and sensory properties. Addition of TNP significantly (p<0.05) increased flour bulk density (0.74–0.84 g/ml), WAC (1.31–1.97 g/g), OAC (1.57–2.00 g/g), swelling capacity (15.33–25.18 ml), but decreased foam capacity (12.05–9.98%) and foam stability (85.56–80.76%). Meanwhile, the cookie sample had a lower moisture content (3.58–3.71%), improved protein (0.91–3.02%), fat (19.72–31.87%), ash (3.27–5.02%) and total dietary fibre (1.84–10.28%) content. Physical parameters of hardness (5.12–10.23 N), weight (10.17–13.05 g) and thickness (6.56–8.03 mm) improved in composite cookies, with a reduction in diameter (46.91–42.67 mm) and spread ratio (7.15–5.13). The total phenolic content (0.689–0.741 mg GAE/g) and antioxidant capacity (10.33–14.61 μmol TE/g) increased, while the microbial population was reduced to a non-detectable level after storage for 28 days. The sensory scores were slightly higher than the control sample. The use of TNP as a functional ingredient in gluten-free cookies is technically feasible, especially for people with coeliac disease.