Antifungal lactic acid bacteria with potential to prolong shelf-life of low salt bread

Mean daily salt intakes of populations in developed countries are well in excess of dietary needs (ca. 3-4 g salt/day). Hypertension, a causal factor for cardiovascular diseases, was shown to be caused by increased amounts of sodium, which is mainly applied as sodium chloride (table salt). Up to 35 % of the daily salt intake is contributed by cereal products, in particular bread. Hence, low-salt bread is one of the most efficient ways to decrease the daily salt intake. The technological process of bread baking as well as some of the final quality characteristics of bread, in particular shelf‑life is influenced by salt reduction. Chemical preservatives, e.g. calcium propionate (CP) are commonly used as antifungal agents. Alternatively, sourdough can be used to retard mould growth. This work addresses the feasibility of salt reduction in wheat bread from 2.0 %* (standard) to 1.0 % (sodium‑reduced), 0.5 % (low‑sodium) and 0.0 % (sodium‑free) from shelf-life perspective. The results were compared to those obtained using 0.5 %* of CP and 20 %* of sourdough fermented by the antifungal strain L. amylovorus DSM 19280. The antifungal “in situ” tests were performed under bakery environmental conditions as well as using challenge tests against F. culmorum, A. niger and P. expansum. Mould growth on the bread slices was observed throughout 14 days of storage. For the environmental trials, a shelf-life of about 5 days was obtained for standard bread (2.0 % salt) while breads elaborated with lower salt concentration were spoiled after 3 days. Sourdough addition prolongs the shelf-life at least up to 12 days and the addition of 0.5 % CP prolonged the shelf‑life 10‑12 days compared to the respective controls without any significant differences regarding the salt levels. Concerning the fungal challenge tests, the spoilage was influenced, with different extent, by both salt level and the fungi tested. Generally, similar antifungal performance was observed in sourdough breads and CP breads when tested against the indicator moulds. The findings of this study indicate that addition of sourdough fermented with the antifungal L. amylovorus DSM 19280 can replace CP addition needed to assure the safety of low-salt bread.