Yeast extract as a NaCl replacer in Lavash flat bread: effects on dough rheology, sensory and textural properties, and microbial stability

The high level of dietary salt is a public health concern, motivating development of salt-reduction strategies for staple foods. This study evaluated replacing sodium chloride (NaCl) with yeast extract (YE) at 0%, 25%, 50%, 75%, and 100% of the original NaCl level (1.5 g/100 g flour) in Lavash flat bread. Proximate composition, dough rheology, color, microstructure [Scanning Electron Microscopy (SEM)], molecular interactions [Fourier-Transform Infrared Spectroscopy (FTIR)] and crystalline structure [X-Ray Diffraction ( XRD)], microbial stability, textural, and sensory acceptability were evaluated. Protein concentration increased from 11.70% to 13.04% at complete replacement. Increasing YE substitution progressively weakened dough rheology; energy decreased from 84 to 18 cm² and resistance to extension from 369 to 91 BU at 135 min, while farinograph stability decreased from 7.18 to 3.00 min and degree of softening increased from 41 to 93 FU. FTIR indicated increased short-range starch ordering, while XRD showed greater intensity of the ∼13° crystalline peak at higher YE levels. In a 12-assessor sensory panel, no significant differences were observed in color, odor, flavor, or overall acceptability; texture differed significantly, with lower scores at complete replacement.Total viable count increased from 123.33 to 3440 CFU/g and yeast/mold counts from 20 to 990 CFU/g at day 0, although all observed counts remained below applicable microbiological limits; counts decreased after 90 days of frozen storage. Overall, partial NaCl replacement with YE, particularly up to 75%, maintained favorable sensory characteristics and increases protein content, while higher replacement levels progressively weakened dough rheological properties. YE may therefore be a feasible partial NaCl-reduction ingredient for Lavash under the conditions studied.