Objective & Methodology
The primary objective of this study was to assess the effect of tap water on the lactic acid bacteria (LAB) population of traditional and mature sourdough, and the establishment of the LAB community during sourdough preparation. Ten tap waters from Italian regions known for their cultural heritage in leavened baked goods were used to refresh a traditional Apulian sourdough or to start a firm (type I) sourdoughs. The same type and batch of flour, recipe, fermentation temperature, and time were used, with water being the only variable parameter. Parameters measured included pH, LAB cell density, and species composition.
Key Findings
Tap waters from different regions showed significant differences in their chemical and microbiological properties
During the nine-day propagation of the traditional Apulian sourdough, the LAB cell density remained stable and LAB species composition hardly changed regardless of the tap water used to refresh it.
All the tap waters tested were suitable to prepare sourdough. Indeed, the pH dropped below 4.5 after two to four fermentations, indicating successful fermentation. These pH values limit the growth of many microorganisms that typically contaminate cereal-based doughs, such as members of the Enterobacteriaceae family.
The type of tap water used to start new sourdough affected the assembly of the LAB biome . Principal Components Analysis showed that the LAB population in sourdoughs and the chemical and microbiological features of the water partly overlapped, suggesting a correlation between water characteristics and sourdough microbiota.
The LAB population in the sourdoughs and the chemical and microbiological features of the tap water used for their preparation partly overlapped, indicating that some minerals, such as magnesium, potassium, sodium, and sulphate, drive the establishment and assembly of the sourdough LAB biota.
Some tap waters harbored additional strains of LAB, including Pediococcus pentosaceus s1, besides the common strains of L. plantarum and L. sanfranciscensis.
Tap water also affected the hardness, gumminess, and chewiness of breads made using the traditional and mature sourdough. Positive correlations were found between bicarbonate concentration in water and bread textural features, while negative correlations were observed with chloride.
The study found that different pH values during early fermentations were influenced by the pH and buffering capacity of the water, as well as the specific effects of minerals on LAB metabolism. Minerals such as sulphate, sodium, potassium, and magnesium also played a role in the fermentation process.
Discussion
The study underscores the importance of water as a variable in sourdough preparation. By understanding the influence of different tap waters on the LAB community and bread texture, bakers can optimize their sourdough fermentation process. The findings also highlight the role of minerals in driving the establishment and assembly of the sourdough LAB biota.
Future Research Directions
Mineral Effects:
Investigate the specific effects of different minerals on LAB metabolism and sourdough fermentation.
Texture Optimization:
Develop models that incorporate water characteristics to enhance bread texture and consumer acceptance.
Q&A
What was the main objective of the study?
The main objective was to assess the effect of tap water used for refreshment on the LAB population of a traditional and mature sourdough and the effect of tap water used to start a sourdough type I on the establishment of the LAB community.
How many tap waters were used for the study, and what criteria were used for their selection?
Ten tap waters from Italian regions known for their cultural heritage in leavened baked goods were used.
What parameters were measured in the study?
Parameters measured included pH, LAB cell density, and species composition. The texture of breads made with the different sourdoughs were evaluated too.
How does tap water affect sourdough characteristics?
Tap water affects the pH levels, LAB population when it is used to start a new sourdough. Bread texture is affected too.
What role do minerals in tap water play in sourdough fermentation?
Minerals such as sulphate, sodium, potassium, and magnesium influence LAB metabolism and the establishment of the sourdough LAB biota, affecting the fermentation process and bread characteristics.
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