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LifeTec™ Sterile Filters Support Organic Yeast Production

Agrano product portfolio
Filters for Organic Yeast Production

If organic, then consistent.

The production of yeast without the usual chemical additives on the basis of organic cereals and clean spring water is a special challenge that Agrano has been meeting since 1996 at its manufacturing plant in Germany. There, in a globally unique process, organic yeast is produced for the baking industry, for the food industry, and for the natural food trade according to the motto "If it's going to be organic, it's going to be consistent!" The production facility works with innovative fermentation techniques that use a new generation of Donaldson sterile filters at various production levels.

Today, 4,000 tons of organic yeast are produced in this plant with an increasing tendency. This yeast differs from conventional yeast primarily in the raw materials used. Managing Director Ralf Bredenhöller explains: "The use of chemicals is dispensed with entirely. We can do this because we are the only yeast factory in the world that can ferment in a sterile manner."

The Yeast

When asked what distinguishes BIOREAL® organic yeast production from the production of conventional yeast, Marc Pflimlin, Head of Production at Agrano, has a clear answer: "Fermentation takes place without chemical additives and organic sunflower oil is used as a defoamer. Only the strict observance of hygiene and sterilization rules at each step of production - production of the organic nutrient medium, sterilization, fermentation, and harvesting - allow us to protect our organic products from any microbiological hazard. In this regard, we must rely especially on filtration technology."

LifeTec™ PT N membrane filter in a PG-EG filter housing for sterile air filtration. Steam for sterilization is supplied through the insulated piping. At a central point, a steam filter with a P-GSL N filter element ensures the required steam quality.
Filtration for High Process and Product Integrity

The Donaldson LifeTec™ PT N filter elements for sterile air and gases ensure that the yeast cultures are kept aerobic, under sterile aeration, in order to obtain the highest possible biomass yield. The required compressed air at 2 bar is generated by two oil-free screw compressors, cooled from 200 °C to 30 °C (392 °F to 86 °F), fed into the pipeline network, and then injected in a metered manner via the sterile filters at the bottom of the fermenters. The oxygen in this compressed sterile air is sufficient to optimally promote the biotechnological process without chemical additives. Air sterility is a factor that has a decisive influence on process and product integrity. The filter technology suitable for this purpose must have a range of performance data that not only provide optimum safety but also enable a long service life for the filter elements. This is because after each batch -  approximately every 30 hours -  the LifeTec™ PT N sterile filters are sterilized for about 20 minutes with 125 °C steam. To ensure that the steam is free of particles, steam filters such as (P)-GSL N elements, are used for each of the three production lines.

Sterile air is supplied to both fermenters via a LifeTec™ PT N membrane filter in a PG-EG filter housing.
The LifeTec™ Membrane Filter

The LifeTec™ PT N filter element is a pleated PTFE membrane filter that is inherently hydrophobic with a highly porous membrane structure and was developed for sterile filtration of compressed air and other process gases. All components meet the requirements for indirect contact with food in accordance with CFR (Code of Federal Regulations) Title 21 and (EC) No. 1935/2004.

The filter media is non-fiber releasing and manufactured without the use of chemical additives. The stable design allows up to 150 sterilization cycles under defined conditions and withstands high differential pressures in both flow directions.

Another outstanding feature of the sterile filters relates to their drying characteristics. Dry blowing and the immediate return to low differential pressures after steam sterilization take place within a few seconds. Downtimes, energy consumption, and the mechanical load on the filter medium are thus significantly reduced.

The steam filter P-GSL N ensures high steam quality. The pleated stainless-steel filter medium achieves high particle and dirt retention at a high flow rate and low differential pressure. The filter can be regenerated in an ultrasonic bath or by backwashing.
The LifeTec™ P-GSL N Steam Filter

The LifeTec™ P-GSL N filter safely retains contaminants such as particles, abrasion from valves and seals, and rust. The improved steam quality extends the service life of the filters to be sterilized and thus increases the cost-effectiveness of the entire process. The P-GSL N filter element offers particularly economical filtration, as the filter medium can be regenerated in an ultrasonic bath or by backwashing.

The pleated stainless-steel filter media ensures high particle or dirt retention and a good flow rate at low differential pressure. Due to its robust design, the P-GSL N filter is rated for maximum differential pressures up to 10 bar. In addition, the filter can be used in a temperature range from - 20 °C (-4 °F) up to 200 °C (392 °F) for the filtration of steam, gases, and liquids.

All components of the P-GSL N comply with FDA food contact requirements under CFR (Code of Federal Regulations) Title 21 and EC/1935/2004 requirements.

Sterile water is supplied to the main fermenter via two filter stages. The multi-place PF-EG filter housings are equipped with LifeTec™ PP N 100 for pre-filtration and LifeTec™ PES-WN for the sterile filter stage.
The LifeTec™ Liquid Filters

To supply the main fermenter with sterile water, LifeTec™ PP 100 N elements with pleated polypropylene membranes are used as prefilters and LifeTec™ PES WN 30 0.2 µm with pleated polyethersulfone membrane for sterile filtration. To ensure that the processes are supplied with water from the company's own well, the water is pumped from a depth of 40 m and sterile filtered via a filtration line with two 8-place filter housings type PF-EG 0830 connected in series.


Agrano Managing Director Ralf Bredenhöller sums up the cooperation with Donaldson: "The new filter systems for sterile air, liquids, and steam used since 2014 have an extremely high value for us in production. For our sterile fermenting yeast factory, high safety is essential."

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