This study aimed to investigate the impact of various ratios (0/100, 5/95, 10/90, and 15/85) of ground psyllium fiber on the quality attributes of rye bread (overbake, specific volume, porosity of the crumb acc. Mohs’s scale, crust and crumb color, texture profile analysis (TPA)). The tested fiber consisted of a mixture of 80% psyllium seeds (Plantago psyllium) and 20% psyllium husk (Plantago ovata Forsk). While both species share similar advantages, they also possess unique properties that warrant the development of a comprehensive blend. The effects on rye bread's chemical composition (moisture, total protein, ash, TDF content), total polyphenolic content (TPC), and antioxidant activity (ABTS, FRAP) were also evaluated. Two types of rye flour (type 580 and 720) and two dough preparation methods (single-phase with paste rye sauer light and two-phase - Dethmold's method) were used in the study.
The inclusion of psyllium fiber in rye bread resulted in an increase in the overbake of bread from 59.4 to 71.8 %, total protein from 8.0 to 9.7 g/100 g d.m., ash from 0.65 to 1.04 g/100 g d.m., and TDF content from 8.9 to 19.0 g/100 g d.m.. Psyllium fiber addition also led to a two-fold improvement in antioxidant activity and an increase in TPC from 35.5 to 109.1 mg GAE/100 g d.m., as well as enhanced porosity of the crumb from 7.1 to 7.6 points on the Mohs' scale. However, it caused a decrease in specific loaf volume by 10%, springiness by 3.5%, chewiness by almost 12%, and gumminess of the crumb by 8.1%. Darkening of the crust (reduction of the L* value from 34.5 to 30.8) and crumb (reduction of the L* value from 55.0 to 34.3) was observed as well.
Notably, the results indicated that a 10% share of psyllium fiber can be considered as a recommended share of this functional ingredient, promoting health benefits, without negatively affecting the physical and sensory qualities of rye bread. The psyllium fiber can be considered as a functional ingredient enhancing the nutritional value of rye bread without compromising its overall quality.
