Effect of hydroxytyrosol, Moringa, and spirulina on the physicochemical properties and nutritional characteristics of gluten-free brownies

Brownies, enriched with fiber and Moringa oleifera, hydroxytyrosol (HXT), and spirulina (encapsulated and nonencapsulated), and dietary fiber using psyllium were elaborated. For that, a commercial control (CTRL) and an experimental control (CTRL) (without antioxidants) were compared. Color, nutritional composition, pH, antioxidant capacity, total phenolic compounds, as well as sensory properties were evaluated. The results showed the brownies developed with psyllium and the different extracts increased total dietary fiber compared to CTRL Commercial and CTRL, with E-spirulina (14.93 g/100 g) and Moringa (11.91 g/100 g) being the most prominent samples. However, with regard to soluble fiber, the highest content of NE-spirulina and the lowest content of HXT were observed. In addition, brownies enriched with extracts showed higher antioxidant capacity and higher phenolic compounds than controls, with HXT standing out at 299.25 μM Trolox/g in ABTS, 1470.08 μM Trolox/g in DPPH, and 18.15 μM Trolox/g in FRAP. However, a high level of phenolic compounds was found in E-Spirulina (604.71 mg/L). In reference to fatty acids, monounsaturated fatty acids (MUFA) (70%) were the predominant fatty acids, followed by polyunsaturated fatty acids (PUFA) (19%) and saturated fatty acids (SFA) (10%). Glutamic acid and asparagine were the predominant amino acids. As for mineral content, N-spirulina and E-spirulina were the brownies with the highest iron bioaccessibility; Si, Na, B, Al, P, Fe, Zn, Bi, Ca, Cu, Mg, Mn, Rb, S, and Sr being the most abundant elements in the brownies of this study. In addition, the HXT and Moringa samples scored higher in overall acceptability compared to the controls. The findings suggest that the incorporation of psyllium, quinoa flour, and antioxidant extracts in brownies could be a viable approach to produce a healthy brownie enriched with fiber, antioxidants and, therefore, considering the nutritional, physicochemical, and organoleptic characteristics, HTX is the ideal compound to enrich bakery products.