Optimization of the use of teff [eragrostis tef (zuccagni) trotter] flour in nutritional enrichment of flour tarhana

This study investigated the effects of using gluten-free and nutrient-rich ancient grain teff flour to enhance the nutritional and functional properties of tarhana, a traditional fermented cereal-yogurt product. Teff flour was substituted for wheat flour at levels of 0%, 20%, 40%, 60%, 80%, and 100% to produce tarhana, and the response surface methodology identified an optimal blend containing 63.27% wheat flour and 36.73% teff flour. Tarhana samples, including the control (100% wheat flour), the optimal blend, and 100% teff flour, were evaluated through chemical, physical, microbiological, functional, and sensory analyses, with tests repeated on days 1 and 90 following a 90-day storage period. The incorporation of teff flour increased dietary fiber from 4.18 to 16.11 mg g⁻¹, iron content from 20.15 to 61.26 mg kg⁻¹, phenolic compound content from 206.07 to 314.08 mg GAE kg⁻¹, and antioxidant activity from 47.53% to 62.07%. Fermentation reduced phytic acid content to 0.00-3.00 mg g⁻¹, thereby enhancing mineral bioavailability, while probiotic lactic acid bacteria (6.25-6.87 log CFU g⁻¹) reinforced tarhana's gut health-supporting and immune-enhancing properties. The addition of teff flour increased water (0.65-0.89 ml g⁻¹) and oil absorption capacities (0.66-0.82 ml g⁻¹), although oil absorption capacity decreased during storage. Sensory analyses revealed that the optimal blend scored highly in taste (8.67), consistency (9.00), and overall acceptability (8.67), but the 100% teff flour tarhana received lower preference due to its darker color tone (L* 74.11). Low pH (4.47-4.65) and moisture content (6.97-8.21%) contributed to pathogen resistance. Teff flour improved the functional properties of tarhana. However, further optimization studies are required to enhance sensory attributes and storage stability.