There are three basic technologies that might have some effect.

The first is super critical fluid extraction- if you are using CO2, you could end up with pressures over 50 MPa. This technology is not commonly thought of as "High Pressure Processing", but it does have a strong body of work showing that it can extract lipophilic compounds quite well. Possible parameters one could investigate include: target pressure*, extraction time, rate of pressure release and temperature*, as well as the possibility of multiple cycles. (*assuming you keep the pressure/ temperature combination in the super-critical range)

The second is what I'll call "High Hydrostatic Pressure"- This is the relatively common static high pressure system, which use water or some other fluid as a pressurizing medium. Product is packaged and placed into a pressure vessel, which is then filled with water and a hydraulic pump raises the pressure to the target value (typically in the 100-800 MPa range) where it is then held for a specified length of time, resulting in the denaturization of proteins (the effect varies based upon the type of protein, and the parameters) and other effects, which may cause the inactivation of undesirable organisms in the food. Possible parameters one could investigate include: target pressure, processing time, rate of pressure release and temperature (assuming the HHP unit has thermal controls built in), as well as the possibility of multiple pressurization cycles.

The third is what I'll call "Continuous high pressure processing", but is also called a number of other terms (one of the more common is ultra-high pressure homogenization) These systems pressurize a pumpable product (typically a liquid, slurry or suspension) to a target pressure (typically in excess of 100 MPa) and pump them through a valve or other release mechanism, exposing them to extreme shear and potentially cavitation, which results in reduction of particle size, disruption of cellular structures, formation of stable emulsions, etc. Possible parameters one could investigate include: target pressure, flow rate, type of valve/release mechanism, temperature, etc.

Simply, you go for super critical extraction process. HPP is not for oil extraction ; it is for processing or texture modification only.

Thanks very much Dr George and Dr Jasim.

I want to applying HPP as pretreatment in virgin coconut oil (VCO) extraction. In this process, HPP applying in coconut meat then continue with water extraction. Can this process make higher at yield and bioctive compounds ?

I cannot say whether it would or wouldn't, but hypothetically it could. My suggestion to you would be to go through the literature and see what effects one might see from such processing, and then determine whether any of those might offer a mechanism for increased yield and/or bio-actives. The literature is rich in HPP papers, and there are likely quite a few observations that could be relevant- as a single example, take the findings of Rastogi and Knorr (2000*), who found that HPP increased the effectiveness of an osmotic drying process, and suggest this is due to increases in cell membrane permeability. If that phenomenon is likely to affect your oil extraction process, then perhaps you could see some benefit in HPP pre-treatment.

* - http://dx.doi.org/10.1016/S0260-8774(00)00037-6

Thanks you very much Dr George. In my country Indonesia HPP is new technology in food processing. Maybe with my research I can increase the yield and value added for food product and agriculture especially for VCO. Thanks for your suggestions and link the journal. Regards

I think that HPP could be effective as pretreatment process before the traditional extraction. In my research HPP  coused extraction of polyphenols (anthocyanins) from strawberry tissue to intercellular juice and the colour were better compared to untreated sample. You can download this article from my publications list. We have also supercritical carbon dioxide equipment so I can recomended my laboratory for colaboration.

Thank you Dr Krystian. Maybe we can discuss seriously about collaboration research. Can I email you, please ?