Natural extracts using supercritical carbon dioxide

1. Introduction..................................................................................................... 1 1.1 Importance of Nature’s Cure................................................................ 1 1.2 Naturopathy .......................................................................................... 1 1.3 Natural Extracts .................................................................................... 2 1.4 CO2 as an SCF Solvent ........................................................................ 3 1.5 SCFE Process ....................................................................................... 5 1.6 SCFE Applications ............................................................................... 7 References......................................................................................................... 9 2. Fundamentals of Supercritical Fluids and Phase Equilibria .................. 11 2.1 Process Schemes and Parameters in SCFE........................................ 11 2.2 Thermodynamics of SCF State .......................................................... 13 2.2.1 Variability of Density with P and T.................................... 13 2.2.2 Addition of Cosolvent to SCF Solvent ............................... 16 2.3 Solubility Behavior in SCF Solvent................................................... 17 2.3.1 Solubility Isotherms and Crossover Phenomena ................ 17 2.3.2 Solubility Isobars................................................................. 20 2.3.3 Pressure and Temperature Effects ....................................... 21 2.3.4 Solvent Capacity and Selectivity ........................................ 24 2.3.5 Cosolvent Effects................................................................. 26 2.4 SCF Phase Equilibrium Behavior ...................................................... 28 2.4.1 Liquid–Fluid Phase Equilibria ............................................ 30 2.4.2 Solid–Fluid Phase Equilibria............................................... 33 2.4.3 Polymer–SCF Phase Equilibria........................................... 34 2.5 Thermodynamic Modeling ................................................................. 37 2.5.1 The Equation of State (EOS) Approach ............................. 38 2.5.2 Solid–Fluid Equilibrium Calculations................................. 39 2.5.2.1 Mixing Rules ..................................................... 40 2.5.2.2 CS and GC Methods ......................................... 42 2.5.3 Solubility Predictions from Pure Component Properties ... 46 2.5.4 Liquid–Fluid Equilibrium Calculations .............................. 50 2.5.4.1 Mixing Rules ..................................................... 51 2.5.4.2 Regression of Binary Adjustable Parameters.... 52 2.5.4.3 Prediction of Multicomponent Data from Binary Interaction Constants............................. 53 2.5.4.4 Prediction of Phase Boundaries ........................ 54 2.5.5 Mixture Critical Point Calculations .................................... 56 2.5.6 Multiphase (LLV) Calculations........................................... 57 © 2000 by CRC Press LLC 2.5.7 Solubility Predictions Using the Solvent-Cluster Interaction Model ................................................................ 59 2.5.8 Solubility Calculations from Correlations .......................... 65 2.5.9 Selectivity of Natural Molecules from Pure Component Solubilities............................................... 69 2.6 Thermophysical Properties of CO2 .................................................... 75 Nomenclature.................................................................................................. 76 References....................................................................................................... 78 3. Fundamental Transport Processes in Supercritical Fluid Extraction.... 83 3.1 Transport Properties ........................................................................... 83 3.1.1 Viscosity............................................................................... 84 3.1.2 Diffusivity ............................................................................ 88 3.1.3 Thermal Conductivity.......................................................... 92 3.1.4 Interfacial Tension ............................................................... 93 3.2 Mass Transfer Behavior...................................................................... 95 3.2.1 SCFE from Solid Feed ........................................................ 96 3.2.2 Mechanism of Transport from Solids ................................. 97 3.2.3 Stages of Extraction for Different Natural Materials ......... 99 3.2.4 SCFF of Liquid Feed......................................................... 100 3.2.5 Fractionation of Liquids by SFC ...................................... 104 3.3 Mass Transfer Modeling for SCFE from Solids.............................. 106 3.3.1 Process Parameters ............................................................ 109 3.3.2 Mass Transfer Coefficients................................................ 109 3.3.3 Effect of Axial Dispersion and Convective Flows............ 115 3.3.4 Shrinking Core Leaching Model....................................... 117 3.4 Heat Transfer in SCF........................................................................ 120 3.4.1 Heat Transfer Coefficients................................................. 120 3.4.2 Effects of Free Convective Flow....................................... 122 3.4.3 Heat Transfer Coefficient for Two-Phase Flow ................ 123 3.4.4 Heat Exchanger Specifications.......................................... 124 Nomenclature................................................................................................ 125 References..................................................................................................... 127 4. Flavor and Fragrance Extracts................................................................. 131 4.1 Market Demand ................................................................................ 131 4.2 Natural Essential Oils....................................................................... 132 4.3 Natural Essential Oil Recovery Methods......................................... 135 4.3.1 Steam Distillation .............................................................. 135 4.3.2 Maceration ......................................................................... 137 4.3.3 Enfleurage .......................................................................... 137 4.3.4 Cold Expression................................................................. 138 4.3.5 Extraction with Volatile Organic Solvents ........................ 138 © 2000 by CRC Press LLC 4.3.6 Choice of Solvents............................................................. 138 4.4 Purification of Crude Extract ........................................................... 141 4.4.1 Vacuum Distillation ........................................................... 142 4.4.2 Molecular Distillation........................................................ 142 4.4.3 Liquid–Liquid Fractionation ............................................. 143 4.5 Supercritical CO2 Extraction ............................................................ 144 4.5.1 Commercial Advantage ..................................................... 145 4.6 SC CO2 Extracted Floral Fragrance................................................. 147 4.6.1 Jasmine Fragrance ............................................................. 147 4.6.2 Rose Fragrance .................................................................. 150 4.6.3 Bitter Orange Flower Fragrance........................................ 152 4.6.4 Lavender Inflorescence Fragrance..................................... 154 4.6.5 Marigold Fragrance ........................................................... 154 4.7 Sandalwood Fragrance ..................................................................... 155 4.8 Vetiver Fragrance.............................................................................. 156 References..................................................................................................... 157 5. Fruit Extracts.............................................................................................. 159 5.1 Importance of Recovery ................................................................... 159 5.2 Citrus Oil Recovery during Juice Production.................................. 159 5.3 Flavoring Components in Fruits....................................................... 161 5.4 Stability and Quality......................................................................... 165 5.5 CO2 Extraction Processes................................................................. 166 5.6 Deterpenation of Citrus Oil by SC CO2 .......................................... 167 5.7 Dealcoholization of Fruit Juice by SC CO2..................................... 170 5.8 Enzyme Inactivation and Sterilization by SC CO2 .......................... 172 References..................................................................................................... 175 6. Spice Extracts.............................................................................................. 177 6.1 Importance of Recovery ................................................................... 177 6.2 Classification of Spices .................................................................... 178 6.3 Therapeutic Properties of Spices...................................................... 178 6.4 Spice Constituents ............................................................................ 183 6.5 Production of Spice Extracts............................................................ 186 6.6 SC CO2 Extraction and Fractionation .............................................. 189 6.6.1 Celery Seeds ...................................................................... 190 6.6.2 Red Chili............................................................................ 191 6.6.3 Paprika ............................................................................... 192 6.6.4 Ginger ................................................................................ 192 6.6.5 Nutmeg............................................................................... 192 6.6.6 Pepper ................................................................................ 193 6.6.7 Vanilla ................................................................................ 193 6.6.8 Cardamom.......................................................................... 194 © 2000 by CRC Press LLC 6.6.9 Fennel, Caraway, and Coriander ....................................... 194 6.6.10 Garlic ................................................................................. 194 6.6.11 Cinnamon........................................................................... 194 6.7 Market Trends................................................................................... 197 References..................................................................................................... 200 7. Herbal Extracts........................................................................................... 201 7.1 Importance of Recovery ................................................................... 201 7.2 Herbal Remedies............................................................................... 203 7.3 Recovery Methods............................................................................ 204 7.3.1 Antioxidative and Antimicrobial Constituents.................. 204 7.3.2 Antiinflammatory Constituents ......................................... 211 7.3.3 Anticancerous Alkaloids.................................................... 212 7.3.4 Anticarcinogenic Polyphenols........................................... 215 7.3.5 Medicinal Constituents of Tea Extract.............................. 215 7.3.6 Fat Regulating Agent......................................................... 218 7.3.7 Therapeutic Oils and Fatty Acids...................................... 220 References..................................................................................................... 222 8. Natural Antioxidants .................................................................................. 225 8.1 Importance of Recovery ................................................................... 225 8.2 Classification..................................................................................... 226 8.3 Botanicals with Antioxidative Activity ............................................ 226 8.4 Tocopherols as Antioxidants ............................................................ 227 8.4.1 Recovery by SC CO2......................................................... 230 8.5 Spice and Herbal Extracts as Antioxidants...................................... 233 8.5.1 Recovery by SC CO2......................................................... 235 8.6 Plant Leaf Extracts as Antioxidants ................................................. 237 8.7 Flavonoids......................................................................................... 239 8.7.1 Recovery of Flavonoids by SC CO2 ................................. 240 8.8 Carotenoids as Antioxidants............................................................. 241 8.8.1 Recovery of β-Carotene by SC CO2 ................................. 242 8.9 Solubility of Antioxidants in SC CO2.............................................. 242 References..................................................................................................... 246 9. Natural Food Colors................................................................................... 249 9.1 Carotenoids as Food Colors ............................................................. 249 9.2 Recovery of Carotenoids by SC CO2............................................... 249 9.2.1 Grass .................................................................................. 254 9.2.2 Orange Peel ....................................................................... 255 9.2.3 Turmeric............................................................................. 256 9.2.4 Paprika ............................................................................... 256 © 2000 by CRC Press LLC 9.2.5 Red Chili............................................................................ 257 9.2.6 Carrot ................................................................................. 258 9.2.7 Marigold Flowers .............................................................. 258 9.2.8 Annatto............................................................................... 259 9.2.9 Other Natural Colors ......................................................... 260 9.3 Anthocyanins as Food Colors .......................................................... 260 9.3.1 Classification of Anthocyanins.......................................... 261 9.4 Recovery of Anthocyanins ............................................................... 262 9.5 Commercial Anthocyanin-Based Food Colors................................. 262 9.6 Betacyanins....................................................................................... 263 References..................................................................................................... 264 10. Plant and Animal Lipids............................................................................ 265 10.1 Importance of Recovery ................................................................... 265 10.2 Recovery Methods............................................................................ 266 10.3 Separation of FFA from Vegetable Oil by SC CO2 ......................... 266 10.4 Fractionation of PUFA from Animal Lipids.................................... 270 10.5 Refining and Deodorization of Vegetable Oil.................................. 271 10.6 Fractionation of Glycerides .............................................................. 275 10.7 Extraction of Oil from Oil-Bearing Materials ................................. 276 10.7.1 Sunflower Oil..................................................................... 279 10.7.2 Corn Germ Oil................................................................... 281 10.7.3 Soybean Oil ....................................................................... 282 10.7.4 Olive Husk Oil................................................................... 283 10.7.5 Grape Seed Oil .................................................................. 284 10.7.6 Animal Lipids.................................................................... 284 10.8 Deoiling of Lecithin by SC CO2 ...................................................... 287 10.8.1 Soya Phospholipids............................................................ 289 10.8.2 Oat Lecithin ....................................................................... 289 10.8.3 Canola Lecithin ................................................................. 290 10.8.4 PC from Deoiled Cottonseed ............................................ 291 10.8.5 PC from Egg Yolk ............................................................. 292 10.9 Dilipidation and Decholesterification of Food................................. 293 10.9.1 Butter ................................................................................. 295 10.9.2 Egg Yolk Powder ............................................................... 297 10.9.3 Fish and Meat Muscles ..................................................... 298 References..................................................................................................... 299 11. Natural Pesticides ....................................................................................... 303 11.1 Importance of Recovery ................................................................... 303 11.2 Bioactivity of Neem ......................................................................... 304 11.3 Neem-Based Pesticides..................................................................... 305 11.3.1 Azadirachtin-Based Formulations ..................................... 307 11.3.2 Commercial Production..................................................... 307 © 2000 by CRC Press LLC 11.4 Recovery of Azadirachtin from Neem Kernel ................................. 308 11.4.1 Conventional Processes ..................................................... 308 11.4.2 SC CO2 Extraction............................................................. 309 11.5 Pyrethrum-Based Pesticides ............................................................. 311 11.5.1 Recovery of Pyrethrins ...................................................... 312 11.6 Nicotine-Based Pesticides ................................................................ 313 11.6.1 Recovery of Nicotine by SC CO2 ..................................... 313 References..................................................................................................... 314 Appendices A Thermophysical Properties of Carbon Dioxide ........................................... 317 B Definitions of Fatty Acids and Their Compositions in Various Oils .......... 321 C Some Statistics on Major Vegetable Oils and Oilseeds............................... 323 © 2000