Characterization of the effect of low-concentration sodium selenite on the microstructure and quality of yeast-leavened steamed bread using X-ray computed tomography

Dough fermentation is an effective method for selenium conversion. This study investigated the effects of low Na₂SeO₃ concentrations on the morphology, texture, fermentation properties, Se species, Se bioaccessibility, and antioxidant capacity of two types of yeast-leaved steamed bread. The results indicated that Na₂SeO₃ did not significantly affect the specific volume; but it did result in increased hardness. X-ray computed tomography revealed that the center of steamed bread became denser owing to Na₂SeO₃, and the porosity was reduced by approximately half at the highest addition level, although the cell number remained relatively unchanged. The fermentation property test demonstrated that Na₂SeO₃ reduced the gas production rate in dough. The conversion rate of seleno-amino acids increased with the addition of Na₂SeO₃, reaching a maximum of over 7 %, as did the antioxidant capacity, although the Se bioaccessibility decreased. In conclusion, this Se-enriched steamed bread reveals its potential functional benefits as a staple food.