Yeasts are unicellular micro-organisms that are used with some fermentation processes in the food industry, for example the production of bread and beer. In general, yeasts are converted into alcohol, water, carbonic acid and aromas during the fermentation process. With the production of bread the alcohol evaporates during the baking process.
|Production process of yeast|
|Dissolving and settling|
|Cooling and pressing|
|Active dry yeast|
The consumption of yeast differs widely around the world. In countries where rice is the primary food, no yeast is consumed. In Europe and the US each resident consumes 2 kg yeast per year.
The production process mentioned below gives a description of the production of bakery yeast. Bakery yeast consists of cells of the division Saccharomyces cerevisisiae.
sugar content is necessary as raw material for the production of yeast. For this molasses is used. This is a by-product of sugar production. In the first place a suspension is made of the molasses with water. Afterwards the suspension is settled down: large particles are removed from the molasses so that a molasses solution is obtained.
temperature of the yeast.
During this phase the graft of the division Saccharomyces cerevisisiae is also added. A graft consists of a very pure and concentrated mass of the desired division.
air is constantly brought into the solution. Yeasts can also survive anaerobic, but the growth will be negligible.
Sometimes extra nutrition, like sugar, is added during the fermentation process.
oxygen is added and the temperature is not regulated anymore. After the fermentation process the yeasts are separated from the solution by means of a centrifuge. The sugar free molasses is transported for further processing for the fodder industry. The mass with a high yeast content is purified.
vacuum filter. The product is brought under a vacuum and past a filter. The filter has such small holes that the yeast cells cannot get through them. In this way, a large part of the water with the salts and acids is removed from the mass. A concentrated and relatively solid mass remains.
Cooling and pressingThe yeast mass is cooled and pressed. Due to the cooling process the consistency of the product increases. For the storage life of the product it has to be cooled down to 3°C at most in order to avoid the growth reinfection. During the pressing process, by means of extrusion, the yeast cells are pressed in a block shape. The yeast blocks are produced in two different sizes.
pressure water with small dissolved salts is pressed through a filter. A concentrated yeast mass is left behind.
conveyor. Subsequently hot air is blown over the product. Because of the air blown through the product the mass does not remain a static layer but is moving. In this way grains of dry yeast are formed. This way of drying is chosen because the temperature is not very high during this process so that the yeast cells do not get damaged but remain active.