Enhancement of Functional, Structural, and Bioactive Properties of Tarhana through Rheum ribes (Işkın) Fortification

This study evaluated the impact of incorporating Rheum ribes L. (Işkın) at different levels (5–20%) on the chemical, functional, structural, and sensory properties of tarhana. The incorporation of Rheum ribes L. exerted a pronounced influence on the compositional and functional attributes of the tarhana formulations. Notably, substantial elevations were detected in total phenolic content and overall antioxidant capacity, accompanied by significant increases in key bioactive constituents such as gallic acid, caffeic acid, ferulic acid, quercetin, luteolin, and catechin hydrate (p < 0.05). Parallel to these biochemical enhancements, the levels of essential minerals including potassium, magnesium, calcium, and phosphorus also rose markedly following enrichment. Insights obtained from FTIR spectroscopy revealed that Rheum ribes L. supplementation induced meaningful alterations in the interactions among proteins, carbohydrates, and phenolic molecules, indicating a more organized and cohesive structural arrangement within the tarhana matrix. Sensory assessments further demonstrated that formulations containing 10–15% Rheum ribes L. achieved the highest acceptability scores, suggesting that this concentration range offers an optimal balance between nutritional enhancement and sensory integrity. Collectively, these outcomes underscore the potential of Rheum ribes L. fortification to substantially improve the nutritional profile, bioactive composition, and consumer appeal of traditional tarhana, thereby reinforcing its value as a promising functional fermented food.