An update from the Nordics
We've successfully wrapped up our sourdough collection campaign in Northern Europe with outstanding results! We received 189 responses in total: 142 from Finland, 25 from Sweden, 17 from Denmark, 4 from Norway, and—surprisingly—1 all the way from New Zealand!
In Finland, the majority of responses were collected from the capital region, accounting for over 30% of the total. Nearly all of the sourdoughs were made at home (96%), with only a few bakeries participating in the survey. Most of the sourdoughs contained wheat flour or a blend of different flours (about 70%), while only 15% were made exclusively with rye flour. This was a surprising outcome, given the popularity of rye bread in Finland. It suggests that wheat flour might be easier for home baking than rye flour. Regardless, the success of the Finnish campaign clearly shows how much Finns love their "sour root." In fact, over 30% of respondents enjoy the taste of sourdough bread, and around 90% believe it is healthier than bread made with regular yeast.
According to tradition, sourdough is typically stored in a glass jar (74%). Half of the participants refresh their sourdough about once a week or every other week, while some do so twice a week or even daily to keep it highly active. The most common temperature range for storing sourdough is room temperature (20-23°C), with a typical fermentation time of 8-12 hours. As for the names people have given their sourdough starters, here are a few examples:
Why rye sourdough bread?
Baking rye bread likely began over 2,000 years ago, when agriculture in Northern Europe was still in its early stages and the climate favored only a few fast-ripening crops, such as rye. The most typical rye bread in the Nordic and Baltic countries is soft, whole-grain rye sourdough bread. In this traditional method, the main ingredients—whole-grain rye flour, water, and sourdough (typically derived from a previous batch through a process known as 'backslopping')—are mixed and fermented for about 8 to 18 hours (Poutanen, K., Katina, K., & Heiniö, R. L. (2014). Rye. Bakery Products Science and Technology, 75-87). Sourdough is crucial in rye bread baking due to the unique characteristics of rye grains. Specifically, α-amylase, an enzyme that breaks down starch into sugars and plays a key role in sourdough baking, is inhibited when the dough’s acidity is relatively high—thanks to the addition of sourdough. This process results in an elastic bread with excellent slicing properties.
In Finland, during the country's 100th anniversary of independence, rye sourdough bread (ruisleipä) was voted as Finland's national food. Rye bread has a deep-rooted history in Finnish culture as a nutritious staple and is even mentioned in the national epic, Kalevala. Finland offers a wide variety of rye breads, with different regions developing slightly distinct versions. One common type is the round, flat loaf with a hole in the middle, traditionally designed to be stored on a pole.
Sourdough biodiversity
More than 1,000 bacteria and yeasts have been isolated from Nordic sourdoughs, and these are now being studied at the University of Helsinki. Our initial analyses revealed 10 different species of lactic acid bacteria, including Fructilactobacillus sanfranciscensis, a key player in sourdough fermentation, which was quite common. We are continuing our exploration to uncover the biodiversity responsible for the unique qualities of Nordic sourdoughs. In the meantime, we want to share a glimpse of the beautiful breads that participants baked.
We also want to extend our warmest thanks to everyone who took part in the campaign! Without your contributions, this research wouldn’t have been possible.
