Salt reduction in bread – Sourdough as a promising solution

The dietary intake of sodium chloride (NaCl) has increased considerably over the last few decades due to changes in the human diet leading to an increase in a number of diseases including hypertension and other cardiovascular health problems [1]. Numerous international health agencies, as well as the food industry, have now recommended a NaCl intake level of about 5–6 g daily, approximately half the average current daily consumption level. Cereal products, and in particular bread, are a major source of NaCl in the human diet of industrialised countries [2]. Therefore, any reduction in the concentration of NaCl in bread would have a major impact on global health. However, NaCl is a critical ingredient in bread production, and its decrease can have a deleterious effect on the production process. This includes an impact on dough handling as well as final bread quality characteristics, such as shelf-life, bread volume and sensory characteristics. In the present study, the impact of NaCl reduction on the dough characteristics was assessed using fundamental and empirical rheological analyses as well as the influence of salt reduction on yeast regarding the aroma profile during proofing. Furthermore, the quality characteristics of the breads were assessed as well as the analyses of the major bread aroma compounds using GC2-MS. Decreasing NaCl addition from current usage levels (1.2 %) 0.6 %, 0.3 % and 0.0 % reduced the dough resistance to extension, extensibility and complex modulus without affecting the ratio of liquid to solid behaviour. An increasing amount of NaCl of 2.0 %, 3.0 % and 4.0 % Changes in gas holding capabilities of doughs with NaCl concentrations between 0.0% and 4.0 % were observed, however affecting the final bread quality for NaCl levels > 0.6 % only. The incorporation of sourdough fermented with Weisella cibaria MG1 and Lactobacillus reuterii FF2 at levels of 10–20 % compensated changes in bread volume and structure. Decreasing amounts of NaCl resulted in major changes regarding microbial shelf-life as well as the analysed aroma compounds. Depending on the amount of NaCl the shelf-life was shortened by 1 to 2 days (NaCl < 1.2 %) and prolonged by 1 to 2 days (NaCl > 1.2 %) respectively. The addition of sourdough fermented with the specific Lactobacillus amylovorus DCM 19280 producing antifungal compounds at a level of 5 % could compensate the lack of salt whereas the addition of 20 % prolonged the shelf-life up to 14 days independent of the NaCl concentration. Differences of aroma profiles could be determined using GC2-MS analyses. The analysis was focused on the compounds which are synthesised through the Ehrlich pathway by yeast cells. With increasing amounts of NaCl in the dough less aroma compounds could be detected. Overall, breads produced with reduced amounts of NaCl (0.3 % and 0.6 %) were found to be comparable to the control (1.2 % NaCl) in terms of dough and bread characteristics and baking performance whereas sensory attributes and aroma profiles showed clear differences between the NaCl concentrations. Sourdough was assesse