Yeast is a living unicellular micro-organism of about one hundredth of a millimetre, and can therefore not be observed with the naked eye.

The scientific name for bakers yeast is saccharomyces cerevisiae. The Latin word "saccharo" means sweet or sugar and "myces" means fungus. Apart from bakers' yeast, there are many more yeast strains, each with their own specific characteristics (e.g. for wine production or for brewing).

Yeast can "live" in two different ways: with oxygen (aerobic fermentation) or without (anaerobic fermentation).   If oxygen and nutrients are present, the yeast will multiply by budding.   As a yeast factory, we use this mechanism to produce yeast.  Yeast production consists in controlling the multiplication in such a way that the specific characteristics of yeast are accentuated for bread production. This is a delicate, high-tech biological process.

Knowledge of micro-organisms and their vital functions has increased considerably over the last few decades.  This knowledge is made use in ongoing research into better yeast strains and basic investigations into the optimization of production circumstances.  Our long-standing experience has allowed us to develop into a leading company in biotechnology.

The production process

Our lab assistants select those yeast strains that are suitable for bread production under very strictly controlled circumstances and allow them to reproduce gradually (until several hundred grammes of yeast are available).

This small quantity of yeast is then transmitted to the factory where it is reproduced until sufficient quantities are obtained of what we call “mother yeast”. This mother yeast is the basis for the production of the actual baker's yeast.

The mother yeast is introduced into fermenters (illustration on the right). These are large fermentation tanks in which nutrients and sugar (in the form of molasses) are added on the one hand, and huge amounts of sterile air on the other. Air compressors blow this air through a ventilation system into the tanks and through the mother yeast. The entire fermentation process is computer controlled. Temperature, pH value, airflow and molasses supply are parameters that are permanently controlled. During fermentation, the yeast is constantly cooled in order to prevent the temperature developed by the yeast during its growth from rising too high.

After fermentation, the yeast is fully-grown and the suspension is subsequently centrifuged in order to separate the yeast from the remainders of molasses. The yeast cream is quickly cooled down to 4°C and stored in refrigerated tanks.

The yeast cream in those refrigerated tanks is then processed into 3 types of yeast products.

Part of the yeast cream is sold as liquid yeast. After standardization, it is conveyed to the customers in tank trucks, in containers or 22-litre packages (Kastalia). A stabilizing agent is added to the yeast packed in containers or 22-litre bags (this is a patent of Algist Bruggeman's). This product is referred to as stabilized yeast cream.

The remaining yeast cream is further processed into fresh or dry yeast. The yeast cream is transferred to a rotating vacuum filter (illustration left) and is spread out on the filter cloth of this rotating drum, thus removing the remaining water until the desired dry substance (about 30%) and consistency are obtained.

Next, the yeast is scraped off the drum with a knife. Some of the yeast flakes obtained are compressed into blocks (block yeast or compressed yeast). The blocks are arranged in cardboard boxes and stored in refrigerated areas (2°C) awaiting transportation to the customers.

The yeast flakes are also on sale loose, in bags; both the block and bagged yeast are called fresh yeast.

Since fresh yeast still contains around 70% water, it will not keep for a long time and is therefore intended for the Belgian market and neighbouring countries, namely the Netherlands, France, Germany, the United Kingdom and Luxembourg. This fresh yeast is meant for both professional and household use.

The remaining yeast that is scraped off the rotating vacuum filter is taken to drying units where the yeast is dehydrated according to a very specific procedure in order to create a granular structure. This is the dry or instant yeast. Dry yeast has a moisture content of maximum 5%, but it becomes viable again after contact with water. This is an important distinction between dried yeast and any other instant product like milk powder or instant coffee.

Next this yeast is carefully vacuum-packed in aluminium bags. Contact with air, water and light must absolutely be avoided as this reduces the activity and shelf life of the dry yeast. After that, the packs are stored.

Dry yeast is mainly designed for export. This type of yeast is also available in professional or household packaging.

During centrifugation and filtration, different waste flows arise. These still contain a lot of proteins and other useful products, and are therefore valorized after evaporation into a side product for the cattle feed industry.

Click here for a diagram of the production process.