Bacillus species fermentations combined with sourdough alter bread function and flavour

A peer‑reviewed study in European Food Research and Technology tested Bacillus spp. fermentations paired with sourdough and found strain- and dose-specific tradeoffs: B. amyloliquefaciens Fad We and B. velezensis FUA2155 at 2.5% produced the highest volume in white loaves but altered flavour enough to reduce consumer acceptance at that dose. The EFRT excerpt reports the work screened seven Bacillus strains, then selected those two “to evaluate their dose‑dependent effect (2.5-0%) on volume and crumb hardening in white flour and 20% bran recipes.”

The EFRT summary gives clear white‑bread gains: “In white bread, both strains resulted in the highest volume when used at 2.5% and crumb hardening was delayed. The softest crumb was obtained with 2.5% B. velezensis.” Those same formulations changed sensory profiles; the paper states that “Bacillus ferments altered the odour and taste profiles of sourdough bread and decreased consumer acceptance in white sourdough bread at a dose of 2.5%.” The report notes that reduced acceptance “was not observed at a lower dosage or in bran breads.”

Effects were different in a 20% bran formula. The EFRT text records: “In bran bread, only 2.5% B. amyloliquefaciens increased volume and crumb hardening was delayed the most by the sole use of sourdough.” That contrast suggests bran inclusion or sourdough alone can mask off‑flavours while preserving anti‑staling benefits.

Context from related work helps explain mechanisms behind these outcomes. A pearl millet sourdough study funded by the Agricultural Biotechnology Research Institute of Iran (grant 3-05-0551-88020) found sourdoughs lowered dough pH, raised titratable acidity and H2O2, increased elasticity and specific volume, and that loaves fermented with Lactobacillus brevis showed the largest gains in loaf height, porosity and moisture retention. Industry R&D at Lesaffre’s Center of Excellence highlights the same principle for preservatives, Lesaffre cites research arguing that “sourdough is one of the best alternatives to chemical preservatives(2)”, and notes co‑fermentations and biodiversity screening to find bacteria that produce antimicrobial compounds.

The EFRT paper’s bibliography points to broader debate: some work examines Bacillus as beneficial fermentation microbes, while other studies address Bacillus‑caused ropy spoilage, indicating a narrow path between benefit and risk. The EFRT conclusion captures that balance: “In conclusion, Bacillus spp. can have a beneficial impact in bread volume and staling delaying when used in controlled conditions and its effect on taste and odour are masked by proper dosing and the use of other ingredients.”

Key follow‑ups remain: the full EFRT methods to confirm what “2.5%” denotes, details of the sourdough composition used, sensory panel size and scoring, and microbial safety screening. If those details confirm scalable dosing and safety, the paper points to a practical route, use controlled Bacillus ferments at lower doses or in bran formulations to gain volume and slow staling without sacrificing flavour.