In this project, new technologies for biorefinery have been developed. In the year 2018, the focus was on anti-solvent extraction of seaweeds, electrostatic separation, mild drying technologies and breaking of emulsions with PEF. This project was commissioned and funded by the ministry of Agriculture, Nature and Fishery of the Netherlands (Ministerie van LNV) in the framework of the knowledge base and investment resources 2015 till 2018 within the research theme: Resource Use Efficiency.
Anti-solvent extraction of seaweeds
WFBR has recently filed a patent on anti-solvent extraction of biomass (WO2019011976A1). In this patent, a process is described where salts are extracted from biomass with ethanol/water mixtures. Through the use of ethanol/water mixtures, the swelling of biomass during extraction is strongly reduced.
Little experience with this method is present. Therefore, it was decided to test this method for extraction of salts from seaweeds. Indeed, the swelling was strongly reduced, and less solvent was needed. A technological and economical assessment (TEA) showed that the reduced swelling also leads to a strong reduction of evaporation energy during drying of the extracted biomass. Savings on energy and dryer size were large enough to pay for the extra costs of ATEX (to reduce the risk of explosion) equipment that will be needed when ethanol is used.
Electro static separation
Electro static separation of powder like materials was developed at WFBR in recent years. In a series of rather academic experiments, it was shown that if a protein rich powder and carbohydrate rich powder are mixed, it is possible to retrieve a protein rich fraction and a carbohydrate rich fraction from this mixture with electro static separation. In 2018, it was tried to separate some real life powders to produce protein rich fractions.
It was shown that several powders that are available on industrial scale could be fractionated to yield protein rich fractions. These fractions are interesting from a commercial point of view. It was shown that fractionated wheat flower could improve the rise of bread.
Mild drying is an important theme in production of high value end-products that are obtained from biorefinery processes. An overview of available processes was made in a poster.
Emulsion breaking with PEF
In biorefinery, the fractionation of high-quality streams is often an expensive and time-consuming step if separation of high-quality proteins and fats from immiscible phases is involved. Often several process steps are needed, including centrifugation or use of chemicals, to separate the protein and fats step by step. A simpler method to separate proteins and fats in one step, without introduction of heat or shear is looked for. In addition, this milder method should also preserve the quality of proteins and fats due to the limited impact of temperature and shear.
One of the options for a mild separation method could be the use of Pulsed Electric Fields (PEF). PEF technology is a technology that is currently applied by industry for the preservation of fruit juices, but also as a pre-step in mass transfer processes in food- and biotechnology to restructure materials, extract compounds, improve cutting, increase yield and enhance product quality.
Interestingly, PEF technology is also used in the petrochemical industry to separate water-in-oil emulsions, and perhaps also offers possibilities to separate the oil-in-water emulsions in biorefinery.
In this biorefinery toolbox development project, a first screening was carried out to evaluate the possibilities of PEF to break oil-in-water emulsions using model systems. Batch PEF equipment with electroporation cuvettes was selected as a tool to evaluate the effect of PEF on the emulsion.
Results of the tests indicated that screening using electroporation cuvettes is a fast and easy way to evaluate the effectivity of a PEF process condition on the creaming of an emulsion over time. Unfortunately, in this study no beneficial effect of the PEF treatment of an oil-in-water emulsion was observed when compared to untreated emulsions. However due to the limited set-up it could not be excluded that PEF couldn’t have a beneficial effect at all. It is advised to further explore a wider range of PEF conditions to investigate if PEF treatment could be possible for this application. The potential advantage of PEF is that due to the lower temperatures and absence of high shear forces, the quality of proteins is much better preserved compared to conventional technologies.