Nutritional, functional and antioxidant evaluation of milk thistle (Silybum marianum) as a substitute for rice flour in gluten-free biscuits

Background: Rice gluten-free products, are perfectly suitable for all patients who are warned against consuming gluten, but these products lack important nutrients that may cause problems in body health. Therefore, milk thistle flour(MTF) is superior source for increasing the nutritional value of these products.
Methods: Proximate analysis, Mineral analysis, the nutritional profile of the biscuits, Antioxidant evaluation, Texture profile analysis, Color parameters and sensory evaluation were determined.
Results: Proximate analysis revealed that milk thistle flour contains significantly higher levels of protein, ash, fat, and dietary fiber compared to rice flour, with protein and iron contents being over three and seven times greater, respectively. Mineral analysis showed milk thistle’s superior content of calcium, potassium, magnesium, and phosphorus. Substitution with MTF led to notable improvements in the nutritional profile of the biscuits, including increased protein (from 6.73% to 7.91%) and fiber (from 2.32% to 2.90%). Antioxidant evaluation showed significantly higher total phenolic and flavonoid contents in milk thistle, alongside stronger DPPH scavenging activity and lower IC₅₀ values compared to rice flour. Texture profile analysis demonstrated that higher MTF inclusion increased hardness while decreasing fracturability and adhesiveness. Color parameters (ΔE*, a*, b*) and sensory scores declined with increasing MTF levels, particularly at 20–25% substitution, due to pigmentation and fiber content. However, lower substitution levels (5–10%) maintained favorable acceptability while enhancing nutritional and antioxidant value. These findings will be helpful in increasing the nutritional value of baked goods, especially gluten-free ones.