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About yeast

It doesn’t matter what bread recipe you choose to start from – traditional Lithuanian rye bread, Italian Ciabatta, or French Baguette – you need to know one important aspect of the bread baking process – the enzymes. Enzymes are live cells mostly accumulated in the outer parts and the germ of the grain, which pass on to flour after grinding the grain. Wholemeal flour ground in a stone mill at a lower speed and lower temperature not only has more microelements, but also more enzymes. That is why this flour is the best for leaven. Rye flour has more enzymes than wheat flour. Why are enzymes so important? Well, particularly the amylase enzyme is involved in the process, during which sugar (maltose) is separated from the starch molecules in the flour, and yeast feeds on that sugar. Enzymes start the process just after mixing the flour with water and are deactivated while baking. That’s why yeast could not survive without enzymes and the following essential process could not happen.

Fermentation, fermentation, fermentation

Without this chemical process involving various microorganisms, including yeast and bacteria, the dough wouldn’t rise, thus you would not be able to bake bread. In order for the process to take place we need the aforementioned yeast. Yeast are unicellular organisms attributed to fungi. Naturally they are found on some plants, fruit and fungi. Currently around 50,000 types of fungi are known, but only approx. 350 of them are attributed to the yeast family. Using yeast for baking bread has been known since 4000 B.C. Yeast is needed for producing CO2 during the anaerobic fermentation process and rising the dough. The production speed of CO2 depends on enzyme activity, concentration, ingredients of the dough, as well as the environment (pH, temperature). Yeast also helps make significant changes in gluten structure, which forms to trap the CO2 produced inside it. Yeast also produces various secondary metabolites, which help produce the aroma of the bread. Fermentation is important not only for fluffing up the bread dough, when yeast produces CO2, the texture, form, volume, taste and aroma of the bread depends on the fermentation process. This process can occur at a temperature of 0-55 0C, but proper fermentation for making bread needs 25-30 0C. Therefore in order to fluff up the bread dough, an effective fermentation process must be started in the dough. You can do this in three ways: by using natural leaven, pre-ferment (also called Biga in Italy, or Poolish in France), or regular bakery yeast for mixing the dough. Yeast is active in the dough in all three ways, but what’s the difference?

Natural leaven

Yes, exactly right, dough mixed with leaven is raised and fluffed by yeast! Of course, it’s not the well-known bakery yeast, but the so-called wild yeast. How does it get into your leaven if you don’t put it in? It’s very simple. Wild yeast already grows on the grain in the fields, from where they travel to the mill along with the grain and are ground into flour. Yeast spores and bacteria are also a plenty in the environment around us. Although to raise bread we need to grow a large enough culture of these living organisms. That is why we make leaven – a medium with all the conditions (moisture, heat, oxygen and “food”) necessary for these organisms to become activated and do their job. Not only wild yeast, but also lactic acid bacteria are active in the leaven, which produce lactic and acetic acids. This process takes 8-12 hours. Only the interaction of these acids and other enzymes create over fifty compounds as secondary products, which in turn provide the taste of the leaven as well as the distinct taste and aroma unique to this type of bread. This acid also improves bread characteristics in terms of storage. Since the concentration of these microorganisms is low in the flour and your environment, it is natural that they need a lot of time to do their job and fluff up the dough. But the taste and aroma of the bread is directly linked to the fermentation period. During a long and slow fermentation, the yeast also creates secondary products – a complex flavour and aroma. After the preparation of your leaven you will realise that it is like a pet – it needs patience, love and care. It needs to be looked after until it grows and matures, as well as the correct temperature, “feeding” and constant attention for it to be maintained and improve.


Pre-ferment is made by mixing flour and water and adding some yeast. This kind of leaven is usually used for mixing dough for French and Italian bread. Bakery yeast is used for preparing the pre-ferment (dry granulated or pressed). What is yeast used for if flour already contains it? It is used to accelerate the rising and baking processes, in other words, to speed up the fermentation processes, and this can only be done by a much higher concentration of yeast. For example, 100 grams of flour can contain 1 to 10 million live microorganisms, only 30,000 of which are the wild yeast. Meanwhile 2.5 grams of bakery yeast (the standard dose for 100 g of flour) has a concentrated dose of 25 billion yeast cells. Therefore, using pre-ferment for mixing bread allows us to utilise all positive features of fermentation, which are essential for the structure, taste and aroma of the bread. The pre-ferment has many names: biga, poolish, chef, levain, sponge, pâte fermentée – but all of them are prepared using the same principle; usually only the amount of water is different. After mixing the ingredients of the pre-ferment – flour, water and yeast – it should be left in room temperature for at least 12 hours. After that it is used for mixing bread dough, usually by adding some more bakery yeast.

The pre-ferment provides an excellent taste for baked goods, very mild acidity, aroma, amazing texture with pores, as well as structural stability, crispiness of the crust, and a high volume and lightness of the baked goods. Also, such baked goods remain fresher for longer. Less yeast is used for bread baked with pre-ferment than that only baked with bakery yeast. You can find Ciabatta and Pica recipes on our website, for which the Biga pre-ferment is used.

Bakery yeast

4 types of bakery yeast are made: pressed, sour cream consistency, active dried and fast-acting active dried yeast. Pressed or dry granulated yeast are usually used for baking bread. Bakery yeast used directly for baking must be activated. This is done by dissolving it in warm water (25 ºC) and adding some sugar and flour. Everything is mixed and left until the mass rises (approx. 15-20 min.). Nowadays the bakery yeast production industry tests and distinguishes some strains of yeast not only to improve the preparation process for the consumer, but also for the yeast to be suitable for as many baking processes as possible. Therefore, the baker, who wants a quick, guaranteed result, should use bakery yeast, since baking with leaven or starting leaven requires a lot of love and the process must be done slowly and patiently.

To conclude…

As we already determined, yeast are live organisms, therefore they inevitably die in unsuitable conditions. Yeast cells die while baking the bread (from at 60 0C), so the most important thing for us, bakers, is the work they do while they’re active, i.e. in the leaven, starter leaven and bread dough.