Modelling and experimental evaluation of high-pressure expression of cocoa nibs

The ability of the Shirato model to describe the expression of dry cocoa nibs in a hydraulic press at pressures of 20–80 MPa was compared with that of a numerically solved conservation laws model based on mass and momentum balances. Experimental data were used to determine the material constants involved in both models at 40, 80 and 100 °C. The Shirato model more accurately describes the final average porosity at different pressures. The Shirato model was therefore used to calculate the influence of the pressure, pressing time and mass of nibs used on the expression process. The calculation results followed the experimentally observed trends. The Shirato model was also used to describe the expression behaviour of cocoa liquor (finely grinded cocoa nibs) at 100 °C and pressures of 20–70 MPa. It was calculated that the filtration stage is absent at these pressures. However, the behaviour of cocoa liquor can only be accurately described with the Shirato model for the last part of the expression process (>100 s)

Gas assisted mechanical expression of oilseeds: Influence of process parameters on oil yield

Gas assisted mechanical expression (GAME) utilizes the solubility of supercritical CO2 in vegetable oils to enhance the oil yields of mechanical expression of oil seeds. The general applicability of GAME was demonstrated with experiments with sesame, linseed, rapeseed, palm kernel and jatropha (hulled and dehulled) at 40 °C and varying mechanical pressures (10–70 MPa). Furthermore, the influence of moisture content, temperature and CO2-pressure on oil yield and rate of seedbed compaction was investigated. Yields obtained with GAME were up to 30 wt.% higher than conventional expression at the same effective mechanical pressure and temperature. GAME yields for hulled and dehulled seeds were very similar, despite the lower yields for hulled seeds in conventional expression. Up to 10 MPa CO2 yield increased significantly with CO2-pressure. The displacement of oil by dissolved CO2 was identified as the major cause of increased oil yields for both hulled and dehulled seeds. The entrainment of oil during CO2 depressurization is another major cause of increasing oil yield for hulled seeds

Ionic liquids, tuneable solvents for intensifying reactions and separations

An Ionic Liquid (IL), or a Room Temperature Ionic Liquid (RTIL), is commonly defined as a liquid entirely composed of ions, which is a fluid below 100 °C. Due to the fact that an ionic liquid is a salt, it has a negligible vapour pressure. Therefore, ionic liquids are not volatile at ambient process conditions. Furthermore, they are non-flammable, have a high thermal stability and a high ionic conductivity. These properties permit their use in many fields. Examples are: reaction media to substitute volatile organic compounds, homogeneous catalysts and extractive media in liquid/liquid extraction and absorption processes

Modelling and experimental evaluation of high-pressure expression of cocoa nibs

The ability of the Shirato model to describe the expression of dry cocoa nibs in a hydraulic press at pressures of 20–80 MPa was compared with that of a numerically solved conservation laws model based on mass and momentum balances. Experimental data were used to determine the material constants involved in both models at 40, 80 and 100 °C. The Shirato model more accurately describes the final average porosity at different pressures. The Shirato model was therefore used to calculate the influence of the pressure, pressing time and mass of nibs used on the expression process. The calculation results followed the experimentally observed trends. The Shirato model was also used to describe the expression behaviour of cocoa liquor (finely grinded cocoa nibs) at 100 °C and pressures of 20–70 MPa. It was calculated that the filtration stage is absent at these pressures. However, the behaviour of cocoa liquor can only be accurately described with the Shirato model for the last part of the expression process (>100 s)

Hydraulic pressing of oilseeds: experimental determination and modeling of yield and pressing rates

The influence of pressure, temperature and moisture content on the oil yield and rate of conventional hydraulic expression of sesame and linseed is discussed as well as the influence of pressure and temperature for rapeseed, palm kernel, jatropha and dehulled jatropha. Yield increased with increase in pressure and with increase in temperature. For both sesame and linseed maximum oil yield was obtained at a moisture content of about 4 wt%. Maximum yields obtained were 45–55 wt% (oil/oil) for hulled seeds (linseed, rapeseed, palm kernel and jatropha) and 70–75 wt% (oil/oil) for dehulled seeds (sesame and dehulled jatropha). Rate of expression increased with an increase in temperature and a decrease in moisture content. Furthermore, the rate of pressing was described by the Shirato model. The increased creep, and thus decreased rate of pressing, observed with increased moisture content was satisfactorily described by the Shirato model