i Contents 2.3 Properties of NCF solutions 24 2.3.1 Solubilities in NCFs General principles Effect of molecular structure Effect of temperature and pressure 2.3.2 Theoretical models (equations of state(EOs)) Entrainers 2.3, 3 Diffusion coefficients 2.4 Factors determining the efficiency of NCF extraction 36 2. 4. 1 Extraction stage Mechanism of extractio The‘ free diffusion’ model,,,,, 38 The‘ shrinking core’ model,, Diffusion coefficient 40 Adsorption The role of water 2.4.2 Separation stage 2.5 Equipment and experimental techniques used in NCF extraction and 2.5.1 Extraction Pilot plants with recirculation Small pilot plant with total loss of CO? 2.5.2 Fractionation Cascades of separation vessels Zosel's 'hot finger'fractionation column 2.6 Applications 2.6.1 Decaffeination of coffee and 2.6.2 Seed oil extraction 2.6.3 Purification of lecithin 2.6. 4 Lowering cholesterol levels in foods 2.6.5 fractionation of high-value oils and fats 53 Butterfat 2.6.6 Extraction of flavours and fragrances 54 2. 7 Reference Pressure-activated membrane processes M.J. Lewis 3.1 Introduction 3.2 Terminology 3.3 Concentration factor and rejection 3.4 Membrane characteristics 3.5 Permeate rate 660012 3.6 Transport phenomena and concentration polarisationvi Contents 2.3 Properties of NCF solutions ....................................... 24 2.3.1 Solubilities in NCFs ........................................ 24 General principles ........................................ 25 Effect of molecular structure .............................. 25 Effect of temperature and pressure ......................... 28 2.3.2 Theoretical models (equations of state (EOS)) ..................... 28 Entrainers ............................................... 34 2.3.3 Diffusion coefficients ........................................ 35 2.4 Factors determining the efficiency of NCF extraction ................... 36 2.4.1 Extraction stage ............................................ 37 Mechanism of extraction ................................... 37 The ‘free diffusion’ model ................................ 38 The ‘shrinking core’ model ............................... 38 Solubility ............. ............................... 40 Diffusion coefficient ...................................... 40 Adsorption .............................................. 40 The role of water ......................................... 41 2.4.2 Separation stage ............................................ 42 Equipment and experimental techniques used in NCF extraction and fractionation ................................................... 44 2.5.1 Extraction ............... ........................ Pilot plants with recirculati ............................... 44 Small pilot plant with total loss of COZ 2.5.2 Fractionation .............................................. 46 2.5 ... Cascades of separation vessels .................... Zosel’s ‘hot finger’ fractionation column 2.6 Applications .............................................. ................... 2.6.1 Decaffeination of coffee and tea ............................... 49 2.6.2 Seed oil extraction .......................................... 51 2.6.3 Purification of lecithin ....................................... 52 2.6.4 Lowering cholesterol levels in foods ............................ 53 2.6.5 Fractionation of high-value oils and fats ......................... 53 Butterfat ................................................ 53 Fish oils ................. ............................ 54 2.6.6 Extraction of flavours and fragrances ........................... 54 2.7 References ..................................................... 57 3 Pressure-activated membrane processes ............................ 65 3.1 Introduction .................................................... 65 3.2 Terminology .................................................... 66 3.3 Concentration factor and rejection .................................. 69 3.4 Membrane characteristics ......................................... 70 3.5 Permeate rate ................................................... 71 3.6 Transport phenomena and concentration polarisation ................... 72 M . J . Lewis