Amonh her many publications is the chapter 'Traditional Polish Breads' in the book 'Traditional European Breads' published in 2023 by Springer Publishing House. With this publication, Życie Uczelni felt compelled to talk to Professor Anna Diowksz about the role of bread in diet, the technology of sourdough production, and the impact of the collaboration between sourdough research centers in the COST project known by the acronym SOURDOMiCS, in which the Professor represented Poland on the Management Committee.
People have known bread for thousands of years. For a technology as traditional as bread making, what is there that can still be improved?
Indeed, bread has been with humankind since the dawn of time. Humans intuitively chose what was best for them. Bread not only satiates hunger. It is also a source of many nutrients.
Polish traditional bread has a distinctive taste and aroma that is hard to resist. Flavorful, crunchy crust and dense, springy crumb that keeps fresh for a long time are the qualities that most bakery products made in other parts of the world lack. This is explained by the fact that the production of bread in Poland is mostly involves mixed wheat-rye and rye breads and those are made with sourdough. This technology, although it has been evolved by generations of bakers, still poses a major challenge for the industry today.
What is a sourdough starter?
In very simple terms, it is fermented flour, in which, as a result of technological procedures that require quite a lot of skill, a specific microbiota is stabilized, usually consisting of a dozen or more strains of lactic bacteria and yeast.
It would be safe to say that it is not just your regular bread eater, but also many a baker who is not in the least aware that baker's sourdough was for millennia, until the advent of commercially produced baker's yeast, the only known raising agent for baked goods.
Well, then, since we now have baker's yeast, why should we bother with the sourdough?
With the introduction of baker's yeast in the second half of the 19th century, the multistage technology of sourdough bread production was almost completely superseded globally by the incomparably simpler and faster method of leavening dough with yeast.
The use of sourdough starter was now almost exclusively limited to small artisan bakeries in those areas of Europe where rye cultivation predominated, as sourdough fermentation-based technology remains a requirement for rye flour bread dough.
Sourdough bread is currently experiencing a revival, including in Western European countries. Why is that?
Catching the tide of increased demand for traditional foods are a growing number of producers who are reverting to the traditional ways of making food products. Sourdough bread is not unique to Poland. The classic French baguette, Italian ciabatta and a range of products from small bakeries, mainly in Mediterranean countries also fall within the sourdough category. And the taste value, in addition to the nutritional benefits of this type of bread, mean that the number of people who enjoy it is growing.
Would it be fair to say then that the quality of bread depends on the fermentation process?
Absolutely. The wide range of metabolites produced by lactic bacteria and yeast during the sourdough fermentation process helps to achieve a much richer flavor and aroma, since sourdough bread contains far more volatile compounds, which, improves palatability, whereas sourdough acidification promotes their retention. The artisan, local character of the production further enhances biodiversity of the microbiota of the produced sourdoughs, which has a direct impact on the variation in the bread produced.
With a technology that dates back to several thousand years ago, what is there to be still tinkered with?
It is not at all a mean feat to get a good quality sourdough starter. Production relies on the fermentation induced by microorganisms that originate mainly in the flour. Although the technology of making bread based on long-term spontaneous fermentation has, in principle, grown alike in every craft bakery, regional differences in the quality of the bread and even differences in the bread made by individual bakers are readily apparent. These differences are a result of the different flour used, the way multi-stage fermentation is carried out, and finally the environmental conditions.
Controlling this process is not a straightforward job, which is why bakery sourdough has become the subject of keen interest for researchers over the past decades, with the microbiota of sourdoughs taking the spotlight. The interactions between microorganisms, as well as between the microbiota and the raw material, the ingredients used and the technological parameters adopted influence to a large extent the properties of the leavening. To further the understanding of the complexity of these processes, highly specialized fields of knowledge such as genomics, metabolomics, proteomics, and biochemistry have evolved. They tend to focus on lactic bacteria, which play a crucial role in the fermentation process.
What you are trying to say is that the research on sourdough starters has quite a lot of range?
The topic of baker's sourdough starters is currently attracting a lot of attention. This subject was one of the main focuses of the COST project SOURDOMiCS, which is now drawing to a close, and in which I have had the honor of representing Poland on the Management Committee. The main goal of the project was to foster multilateral cooperation between sourdough research centers. It involved as many as 250 partners from 54 countries around the world. Moreover, more than 20 small and medium-sized enterprises and large manufacturers from Europe, Africa and the Americas were also engaged in its activities.
As is suggested by the name of the project, namely Sourdough biotechnology network towards novel, healthier, and sustainable food and bioprocesses, its thematic scope spanned bakery sourdough technology in the broadest sense, from sustainable grain production, through fermentation processes, to by-product management under the principles of circular bioeconomy.
What do researchers do when they study levain?
Project executors worked in teams that specialized in conventional and unconventional grain seed testing, sourdough microbiota screening, starter culture development, functional metabolite extraction, enzymatic process improvement, innovative product development, by-product management, food safety, consumer research, economic aspects, and sustainability.
Has the project met its objectives?
Although the carrying out of the 4-year project largely coincided with the pandemic, which significantly constrained the opportunities for direct contacts and limited the number of previously planned trainings, internships, and conferences, international research cooperation has nevertheless been established. It has already resulted in collaborative publications and books, including a compendium on traditional European breads, which includes a chapter on Polish bread.
Was the collaboration in the project representative also of research collaboration?
The very idea of COST projects in general does not actually involve research funding. Nevertheless, the large-scale efforts now underway geared toward the isolation and identification of sourdough-specific strains and the development of specialized biobanks where they are deposited are definitely a measurable result of focusing on sourdough starters.
It is important to understand that the appeal of traditional sourdough products is rooted in their great variety, and that behind that variety stands the biodiversity of microorganisms identified in mature sourdough starters. As proven by painstaking microbiological studies conducted around the world, especially abundant in European countries, although the typical sourdough starter microbiota anywhere is made up of lactic bacteria and yeasts forming complex multicomponent consortia, their species diversity is nevertheless peculiar to each region.
What would you attribute this to?
Geographical location and the prevailing local microclimate, the type of raw material used in bread production, its chemical composition, as well as the condition of the flour microbiota, they all are a factor, to be sure, but the practices of artisan bakers typical of the traditions of the region cannot be overestimated either. Experienced bakers have the ability to manage the fermentation process in a way that allows them to achieve the most desirable result. They know when the texture and density of the dough is just right, what the optimal temperature and time of fermentation are at each stage of the process.
But what if the quality of the levain is not up to par? Or when a baking goods manufacturer finds that they are simply incapable of handling the difficult process of sourdough starter renewal, if only for lack of well-qualified staff?
This is when starter cultures - preparations of selected microorganisms that, when added to a fresh batch of flour and water, initiate the fermentation process - can come in handy. And this brings us back to the idea of biobanks. To achieve the anticipated benefits of fermentation starters, the right strains need to be carefully selected for the desired technological effect, but at the same time they need to be able to compete with the microorganisms already present in the bakery environment, dominate the microbiota and take control of the fermentation process.
How do you make these starters?
The composition of starter cultures for industrial applications relies on precisely specified metabolic aptitudes of microorganisms. This helps to design starters tailored to the specific needs of a given manufacturer, accurately characterizing the expected quality of the final product.
Sourdough starters used in long-established artisan bakeries renowned for their high-quality bread are certainly the most interesting research resource when it comes to harvesting microorganisms for designing starter cultures. Not only does this approach prevent the legacy of the previous generations of bakers fall into oblivion, but it also helps the preservation of distinctive regional flavors.
What else is there to investigate about baked goods?
When it comes to baking technology, there seems to be plenty of research topics. A great deal of attention is given to developing new recipes, including fortification of bread with bioactive compounds, since bread as a food product consumed universally and on a daily basis is a pretty good carrier of them. Another tremendous research effort is currently directed toward the production of gluten-free bread, which is a major technological challenge. Incidentally, too hasty adoption of a gluten-free diet by some consumers and/or complete exclusion of bread from the diet is in itself an issue, but it is probably a topic for another conversation.