Optimisation and integration of membrane processes: Recent developments in the starch and yeast industries

Frank Lipnizki, Mattias Nilsson

Research output: Contribution to conferenceAbstract


The starch and yeast industries are two key sectors of the European food industry, with annual turnovers of approx. € 4 billion and € 500 million, respectively, in Europe alone. The production processes in the starch and yeast industries are still dominated by conventional separation processes such as evaporators, separators and rotary vacuum filters (RVFs), and membrane processes are only rarely used. This presentation will show how membrane processes can be used to optimise the production process resulting in improved products produced in more economical and environmentally friendly ways.
In the starch industry, the focus will be on (1) mud removal after saccarification and (2) pyrogen removal in the starch-based sweetener production. Conventionally, RVFs with diatomaceous earth (kieselguhr) coating are used for removal of the so-called mud phase consisting of enzymes, proteins etc. after the saccarification step. In a novel approach, a hybrid process consisting of a two-phase decanter combined with ultrafiltration spiral wound modules is used for demudding. This approach does not only overcome the disadvantages commonly linked to the use of kieselguhr such as high disposal costs, sugar losses in the mud fraction and safety of operators but also achieves higher colour removal and thus reduces the load on the subsequent ion-exchange columns. Further, ultrafiltration can be applied in the production of pyrogen-free sweeteners with high purity replacing the cascades of kieselguhr and cartridge filters conventionally used. In the ultrafiltration process, the feed stream is separated into a permeate stream of purified sweeteners and a retentate stream containing the high molecular weight colour fraction, germs and pyrogen resulting in high-quality products.
In the yeast industry, the selected applications are related to the production of yeast extract and highlight the use of membrane processes for (1) optimisation and (2) concentration of yeast extract, a flavour enhancer. In the yeast extract production, RVFs are used for polishing of the yeast extract before final concentration. Ultrafiltration can be used to polish the yeast extract by removal of suspended proteins, polysaccharides, bacteria, enzymes and yeast cells without the use of kieselguhr. Hence, a higher product quality is achieved at lower environmental impact. Further, reverse osmosis can be used as pre-concentration step before evaporation, thus removing one of the evaporator steps. This process synergy does not only provide a more gentle product handling at costs comparable to conventional straight-forward evaporation but also reduces the overall operating costs by lower energy consumption.
In conclusion, as this presentation demonstrates, membrane processes improve the production of yeast and starch products at the same time resulting in better products and therefore contribute to a sustainable growth of these industries.
Original languageEnglish
Publication statusPublished - 2009
Externally publishedYes
EventEuromembrane 2009 - Le Corum - Palais des Congrés, Montpellier, France
Duration: 2009 Sept 62009 Sept 10


ConferenceEuromembrane 2009

Subject classification (UKÄ)

  • Chemical Engineering

Free keywords

  • Membrane separation
  • food industry
  • Yeast
  • Starch


Dive into the research topics of 'Optimisation and integration of membrane processes: Recent developments in the starch and yeast industries'. Together they form a unique fingerprint.

Cite this