Development of gluten-free tarhana formulations: Part II. Utilization of legume composite flours and baker's yeast

Many gluten-free foods are prepared from starch-rich ingredients with low protein and fiber content, resulting in poor nutritional and functional quality. In this study, five different composite legume flours which are prepared from different levels of chickpea, lentil, common bean, soybean and lupin flours were used at 75% level in gluten-free tarhana formulations to improve nutritional quality. Also, effect of baker's yeast (Saccharomyces cerevisiae) at different levels (2.5% and 5.0%) on physicochemical and sensory attributes of the samples con-taining composite flours was investigated. The inclusion of composite flours (75%) resulted in lower L* and hue values in tarhana than gluten-free sample without composite flour. The viscosity of tarhana soup containing "25% chickpea+50% lentil" composite flour (F2) was similar to traditional wheat tarhana soup (p > 0.05). The utilization of composite flours containing "50% chickpea+25% lentil" (F1), F2, and "25% chickpea+25% lentil+25% common bean" (F3) in tarhana revealed comparable oil absorption capacity to wheat tarhana. Be-sides, pH and foaming capacity values of the samples containing composite flours were greater than wheat tarhana and gluten-free tarhana without composite flour. The addition of composite flours elicited markedly higher ash, protein, fat, and mineral content. While phytic acid concentration of tarhana enhanced with the incorporation of composite flour, the use of 5.0% yeast considerably decreased phytic acid content and enriched ash, protein, total phenolic content, Ca, Cu, K, Mg, and P concentrations of tarhana in comparison with tarhana containing 2.5% yeast. The inclusion of F1, F2, and F3 elicited acceptable sensory scores in tarhana. It was concluded that gluten-free tarhana prepared from legume composite flours (especially F1, F2, and F3) + 5.0% yeast could offer a nutritious and acceptable alternative for gluten-free diet with greater protein and mineral contents. Based on the findings, further studies may evaluate the use of hydrocolloids to improve the techno-logical and sensory properties of functional tarhana formulations developed in this study.