Yeast

July 14, 2012

Another defining ingredient in the bread is the kind of yeast, if any, that is chosen to raise the bread. The bread finds that can be dated back to the Viking Age in Scandinavia are generally unleavened, but a few of the breads or breadlike finds have either gas bubbles or in a rare occasion some possible remains of yeast. This seem to indicate that the common bread generally was unleavened. However, as a representation of the more southern traditions, where both ovens and and rye were more common these thoughts are aimed at the leavened breads of the Viking Age.

Looking at the conditions and finds one may recognise three fermentation methods that may have been used in Viking Age Scandinavia; spontaneous fermentation, sourdough and beer yeast.

This coincides quite well with the methods observed by Keyland in “Svensk allmogekost.” According to Keyland three methods of fermentation were traditionally used in Sweden prior to the 20th century, self fermentation, sourdough and beer yeast.

Self fermentation/self souring

The first method is described as the most original but also the most uncommon. Basically it is quite similar to the methods of making sourdough albeit without a starter. Wheatflour is mixed with water to make a thick dugh which is then left to stand for about a week. However at this point it was not considered fit for fermenting bread but to make some kind of weak beer. In order for the “dough” to be able to ferment a bread it had to undergo the process of brewing first.

A similar method is described by Olaus Magnus as being the way beer is brewed in Ethiopia. Wheat and barley are worked into a dough. It is left for ten days, during which some flour are added and the dough is kneaded. After ten days it is shaped into small breads, after which it is baked or perhaps rather dried. When it is time to set a beer the bread is broken into a pot containing malt. This description is quite close to the descriptions we have from ancient Egypt, where the connection between bakeries and breweries were very close.

A variety of this is described as partial self fermentation. This type of fermentation is described to have only taken 24 hours. The dough or flour is scalded with hot water or wort. It is then given a day during which flour is added and kneaded. The would certainly give some characteristics to the bread, and I could imagine that it would work well with a bread baked in a baking bell.

Sourdoughs

In contrast to the sourdoughs of today with an almost batter like consistency, the traditional sourdoughs in Scandinavia seem to have been more like a dough. Commonly sourdough seem to have referred to fermentation through remains of earlier batches of dough either through a conscious collection of doughremains from the trough or through such remains that may still be present in cracks and pores. Keyland gives a few examples of 19th century sourdoughs:

  1. The dough sticking to the trough is left there from one batch to the other and the yeast that survives will be used to raise the dough. In some traditions the bun or ball were cut with a cross on the top ( More exposed surface may have helped the fermentation). If the bun did not ferment properly it should be fed more flour. That is the sourdough is added to some luke warm water and some flour in the trough.

  2. Another common way to produce a sourdough would be to scrape of the dough from the trough and shape it into a small ball, which is left to dry in trough…when baking bread the ball is soften with luke warm water and flour and then mixed into the dough.

  3. Another rather straightforward way was to just keep a bit of the dough from the previous batch in a jar of flour. Since flour most likely were milled for each batch rather than for the whole season this may have been a less likely method.

It does make sense though that the sourdoughs were more or less made as a dough rather than a batter. In an era with a limited number of storage vessels for liquids which were not prone to lose some of the liquid, a batter may prove difficult to keep. Today, with glass jars and plastic containers battered sourdoughs are more practical.

Both selffermenting/souring and sourdough would acidify the dough, which in turn would alleviate baking a bread of rye.

Beeryeast / the dregs

Finally and perhaps most like the yeast today is the possibility to use the dregs or the forth of the yeast from brewing. The connection between baking and brewing were early apparent, perhaps most strikingly so in the breweries in ancient Egypt, where baking ad brewing went hand in hand. In a more European context this connection can be observed through the words of some puzzled Romans. When visiting the Iberian colonies, Pliny observed that the bread there was much lighter and fluffier than the bread back home even if it was not as white as the Roman breads. It is likely that the bread that he had encountered was fermented with the help of beer yeast as the Iberians at the time were well known for being good brewers.

In Scandinavia the use of brewing yeast was favoured during the from the 18th to the 19th century when it was replaced by the more modern baking yeast. However the connection between brewing and baking was probably well known even when we even if the biochemistry behind it was not known. In traditional descriptions we are told to take the dregs from the bottom of the beer vat when baking and as the beer is finished the remaining yeast was taken out or either stored as a liquid or as small dried buns, which are dissolved in the baking liquid when one should bake.

 What would have been the more likely method in the given context? Though most breads seem to have been unleavened at the time, it does not exclude the possibility that rye breads in the south at times were leavened. Exactly what method was used to leaven the bread is difficult to discern.

 The limitations in the Viking kitchen and the flour used would have influence how and what types of leavening were used. From finds we know that baking troughs of various sizes were used. However, containers for liquids that were protected against seepage were somewhat more limited: leather bags, staved vessels and waxed jars of pottery could all have been used but would not really have been fitting for a small amount of liquid sourdough. The lack of liquid sourdough in texts and descriptions from the 19th century makes it less likely that it were used as a leavening during the studied period. Considering, though, that the imagined bread is based on rye, the acidity of a sourdough is more or less essential.

 It is easy to imagine that the differing methods were used in a cycle of sorts, a cycle that most likely were distorted due to feasts and other occasions that influenced what bread were to be baked.

First, a self-fermenting dough were used in order to start the fermentation process, according to Keyland it was at this stage not powerful enough to be used for bread but needed rather

to be used in a low alcohol beer, “dricka”.

The dregs, or remaining yeast from the brew could then have been used either to start a new batch of stronger beer or to bake some bread. If used for a rye bread it were perhaps still left to self-ferment for sometime in order to increase the acidity.

A successful batch of the above dough would at this point (according to Keyland) be strong enough – have enough of the proper yeast – so that the remains in the trough could be gathered up, stored and used for the next batch of bread. Leaving it like this would also keep acidifying the dough making it even more suitable for making rye bread. When ever the fermentation went awry, due to mould, the wrong kind of yeast or if the yeast died the cycle would start over. Ofcourse this order would have been broken up in various ways. If one were baking for a large feast it would hve been likely that some ale yeast were added. If baking in a baking bell it would perhaps have been enough to just use a self-fermented dough

One should keep in mind though that most of the finds seem to indicate that the common bread was unleavened. This would have made the dough remains of the troughs bad starters and they would then need some kind of ale yeast to get started.

With the last thing in mind I would suggest that the bread in this exercise should be fermented using a dough that is left to self ferment but with an addition of yeast from a brew.

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2 Responses to “Yeast”

  1. A. Klumpp said

    Another method for “yeasting” is described by the romans and was used by romans, celts and possibly in the early middel ages for high quality baking:

    the yeast of mead.

    It would work best with wheat, spelt, emmer, einkorn or some other of the same family. The result would be a somewhat sweet cakelike bread if you use it in moderation or sweet cookies and hony cakes if used in excess. The taste can be transformed by using different ingredients, like herbs or hops, in mead making.

    One example is the so called “Keltenringli” or “Keltenkringli” found in a grave in Wederath/ Belginum

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