High Efficiency Continuous Oilseed Cryo-Pressing Process

Wednesday, 09 September 2015

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The production of rapeseed oil is a fast growing sector due to its diverse uses. It can be used as an alternative straight fuel, bio-diesel and is fit for human consumption. It has caused a ‘rapeseed revolution’ in the food market, being hailed as the ‘British olive oil’ as celebrity chefs like James Martin have declared open devotion to its flavour. It also has a selection of health benefits, such as being high in vitamin E and having half the saturated fat content of olive oil. 

The largest current producers of Rapeseed oil is the EU, producing 19.2 Million Tonnes in 2012, followed closely by Canada(15.4 Million Tonnes) and China(14 Million Tonnes). It is currently the preferred oil stock for bio-diesel production in Europe and accounts for around 80% of the feedstock. This is mainly because it has a much gel point than most other vegetable oils, but also because it produces more oil per unit of land area compared to other oil sources, e.g. Soy beans. 66% of the total production of rapeseed oil in the EU was expected to be used for bio-diesel between 2010 and 2011. 

Vegetable oils can be extracted from oilseeds by mechanical means alone or in combination with a solvent extraction. The process of vegetable oil mechanical extraction is carried out, using continuous presses, commonly known as expellers, at hot or cold press conditions.

Traditional oilseed conditioning methods involve the use of high temperatures that are detrimental to the quality of the produced oils; a mild but efficient process is therefore desirable. Traditional cold press extraction produces higher quality oils but at much lower extraction efficiency, the subsequent press cake has a larger percentage of residual oil that ultimately represents a loss of potential income for small-scale vegetable oil producers.

Problem Being Solved

Rapeseed oil can to be extracted from the seed material using mechanical presses (expellers), chemical process or a combination of both. The chemical process (solvent extraction) is highly efficient but capital intensive and it is also considered unsafe due to the use of flammable chemical solvents.

Solvent extraction is used in operations which process many tons per hour, while mechanical presses are used for processing seeds in the order of kilograms per hour. 

Mechanical presses are quite simple in construction but far less efficient in terms of oil extraction when compared to solvent extraction and as a result, a large percentage of the vegetable oil is left in the presscake (the solid residue after the pressing process).

Typical residual oil in the presscake from modern commercial expeller is between 8% and 12%. The residual oil is considered a financial loss to an oilseed processer, as it normally does not add to the monetary value of the press cake. Therefore a high efficiency expeller can increase the profitability of small to median size vegetable oil extraction operation. 

Traditional press cakes in use with traditional expellers also leave the expeller with a residual oil content of about 20%. This leaves the producer with a large oil loss with nearly 1/3 of the rapeseed oil produced being wasted due to inefficient machinery that until now has been the only way to produce rapeseed oil. This means that every three tonnes of oil produced, one tonne is wasted due to inefficiency. The price of Rapeseed oil in 2012 is $1258 (USD/Tonne) this means that by the time the source has produced $3774; they will have lost a potential $1258 through unnecessary wastage.     

Technology

In response to this requirement for increased efficiency whilst maintaining high quality standards and reducing further downstream processing, scientists at Ulster University have developed a patent pending innovative technology for the production of superior quality cold pressed vegetable oils. The currently well-established expeller process working in combination with a novel pressure and temperature control regime with additional screw and barrel design alterations produces the superior oil. The result is the production of raw oil with low solids content (footings) that requires no degumming, obtained at higher efficiencies and with the capacity to utilise oilseeds with wider percentage moisture content.

 

All Oilseeds, in addition to oil, cell wall components, and husks, also contain variable amounts of proteins. Proteins, like most of the main oilseeds polymers, have a glass transition temperature (Tg) that is dependent on moisture content.

As the glass transition temperature of oilseed press cake is dependent on its moisture content, it will shift to higher temperatures with decreases in moisture and vice versa. The press cake has to be maintained at it`s glass transition temperature (Tg) for high extraction efficiencies too be achieved. 

The Tg range is where amorphous polymers undergo a transition from a hard brittle state to elastic state. This transformation causes many changes but most importantly for mechanical oil extraction, there is a drastic decrease in intermolecular viscosity with increases in temperature above the Tg.    

Benefits/Applications

The ‘High Efficiency Continuous Oilseed Press And Oilseed Cryo-Pressing Process’. This process guarantees a lower wastage in oil production by over 80%. This means that per 3 tonnes produced, this process can save the producer over $1000.

The Cryopress process takes advantage of the seeds Tg dependence on moisture content and phospholipids polymorphism to produce raw oils with extremely low levels of phospholipids at high extraction efficiencies.    

Opportunity/Partnership Sought

Fergus Begley
Technology Commercialisation Manager
Research and Innovation
Ulster University
Magee campus
Derry
BT48 7SL

Tel: 028 71675636

Email: fm.begley@ulster.ac.uk

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