Yeast Extract
The spectrum of potential end products which can be made with the aid of yeast extract ranges from flavor enhancers to spreads to animal feed yeast. The starting material for obtaining this intracellular product can be fresh cultures specifically for the intended use in question or by-products of fermentative processes such as debitterized beer yeasts, for example.
The yeast cells can be lyzed (i.e. disintegrated and perforated) by thermal, mechanical, chemical or enzymatic processes. Nozzle separators from GEA Westfalia Separator then separate the extract from the cell walls. In principle, this is a multi-stage process on the counter-current principle. There are no standard solutions, because aspects such as the separability of the product, the requirement for wash water or the yield of extract have to be taken into account on an individual, customer-specific basis.
To design the separation stage perfectly, the process and product parameters in question have to be taken into account; these might include the density of the liquid and the solid, particle size and viscosity. Multi-stage counter-current washing can be considered the most frequently used process. The nozzle separators of the HFA generation ensure optimum clarification efficiency here.
If the precipitation of protein is also required, for example in the case of cooling, self-cleaning high-performance clarifiers of the HSB type are also available as an option.
Integrated process line from GEA Westfalia Separator for obtaining yeast extract
4-stage separation
The optimum result is achieved by 4-stage separation. The cell wall suspension to be separated is fed to the first separator via a rotary brush strainer to protect the separators from damage or nozzle blockages due to coarse particles. The clear phase of the second separator is added as early as the feed for the first separator.
The concentrate of each separation step is then diluted with the clear phase of each subsequent step on the counter-current principle. Fresh water is added only to wash the concentrate from the third separator.
The valuable soluble elements from the cell wall suspension which have been separated in this way are concentrated by a thermal process in subsequent process steps before finally passing to packing.
Additional washing stages allow the consumption of fresh water to be reduced further without the washing effect being reduced. The associated reduced dilution of the extract has a positive impact on the energy balance of subsequent thermal concentration processes and thus makes a considerable contribution to the economy of the process as a whole.