Transforming traditional tarhana into a functional food: Impact of pulse flour substitution on nutritional and rheological properties

Abstract

The rising demand for functional food products has sparked interest in integrating pulse-based ingredients into traditional foods. This study investigated the effects of replacing 50 % of wheat flour (WF) with pulse flours, pinto bean flour (PBF), chickpea flour (CPF), yellow pea flour (YPF), and red lentil flour (RLF), on the physical, nutritional and functional properties of tarhana, a traditional fermented food from the Middle East and Southeastern Europe. Replacement of WF with pulse flours significantly (p < 0.05) enhanced the protein content of tarhana powders. Mineral analysis revealed significant increases in key micronutrients, such as Mg, P, Fe, and Zn, particularly in PBF and CPF-substituted formulations, contributing positively to the recommended dietary allowance of these minerals. The in-vitro protein digestibility (IVPD) of pulse flour-substituted tarhana remained above 78 %, with YPF-substituted tarhana demonstrating the highest IVPD (81.63 %). The replacement of WF with pulse flours also led to a significant (p < 0.05) increase in total phenolic content, with the highest levels observed in PBF-substituted tarhana (849.72 mg GAE/100 g db), along with enhanced antioxidant capacity. Phenolic profiling confirmed increased levels of key bioactive compounds, including catechin, myricetin, quercetin, and ferulic acid, in pulse flour-substituted tarhana powders. Rheology tests showed that replacement of WF with pulse flours significantly (p < 0.05) lowered the viscosity of tarhana soups. These findings highlight the potential of pulse flours to enhance the nutritional and functional properties of tarhana, transforming this traditional food into a nutritionally-denser, functional food.