Development of oleaster-enriched functional bread using mechanically aerated frozen dough: Nutritional enhancement, rheological properties, and process optimization

Background: Oleaster (Elaeagnus angustifolia L.) fruit is a promising plant ingredient for functional bakery products because its incorporation can enhance the nutritional profile of cereal-based foods. However, using oleaster fruit powder in mechanically aerated frozen dough is technologically challenging because the gas-cell structure forms before freezing and, in the absence of yeast fermentation, cannot be restored after thawing. Therefore, functional enrichment must be coordinated with processing conditions to maintain dough structure and final bread quality. Objective: This study aimed to develop oleaster-enriched functional bread using mechanically aerated frozen dough and to determine the appropriate level of oleaster fruit powder and processing conditions that provide nutritional enhancement while maintaining rheological, structural, and sensory quality. Methods: Wheat flour was replaced with oleaster fruit powder at 10%, 20%, and 30%, and the formulations were initially evaluated to select an appropriate enrichment level. The selected 20% formulation was then investigated using a 2⁴ full-factorial design that varied whipping speed (450 and 900 rpm), whipping time (3 and 7 min), microwave thawing time (4 and 8 min), and freezing temperature (−38 and −14 °C). Dough rheological and deformation properties, bread quality characteristics, nutritional composition, and sensory acceptability were evaluated. Results: Of the substitution levels tested, 20% oleaster fruit powder provided the best balance between enrichment and technological performance. Processing conditions substantially affected the properties of mechanically aerated frozen dough and the resulting bread. Among the treatments tested, Sample No. 7, produced at 900 rpm with 3 min of whipping, 4 min of microwave thawing, and freezing at −38 °C, demonstrated the best overall technological response. It achieved a specific loaf volume of 242 ± 4 cm³/100 g, crumb porosity of 57.7 ± 1.0%, elastic deformation (H₃) of 0.914 ± 0.028 mm, and overall sensory acceptability of 4.90 ± 0.06. Oleaster-enriched bread also had higher protein and dietary fiber contents ( up 9.7 ± 0.2 and 7.2 ± 0.2 g/100 g, respectively). Novelty of the Study: This study combines oleaster fruit powder enrichment with mechanical dough aeration and frozen storage. Unlike conventional fermented bread, this approach uses a yeast-free dough. The study demonstrates that a 20% oleaster substitution can be paired with coordinated control of aeration, freezing, and microwave thawing to produce nutritionally enriched bread while maintaining acceptable structural and sensory characteristics. Conclusion: Oleaster fruit powder can be incorporated at 20% into mechanically aerated frozen bread to enhance its nutritional profile while maintaining satisfactory technological and sensory properties when processing conditions are properly controlled. Rapid freezing at −38 °C, combined with high-speed, short-duration aeration and 4 min of microwave thawing, yielded the best results among the tested treatments. These findings support the use of oleaster fruit powder as a plant-based functional ingredient and provide a technological basis for developing nutritionally enhanced frozen bakery products without added baker’s yeast. Keywords: Elaeagnus angustifolia L.; oleaster fruit powder; functional bread; functional food; dietary fiber; mechanically aerated dough; frozen dough; nutritional enrichment; dough rheology; processing optimization.