Chemistry and Analysis of Hop and Beer Bitter Acids (eBook)

Front Cover 1
Chemistry and Analysis of Hop and Beer Bitter Acids 4
Copyright Page 5
Table of Contents 10
Preface 8
Chapter 1. Hops as a raw material in the brewery 22
1.1. Occurrence of hops 22
1.2. Origin and history 22
1.3. Hop as a botanical species 23
1.4. Hop as a commercial plant 28
1.5. References to Chapter 1 35
Chapter 2. The alpha acids 38
2.1. Structure of the alpha acids 38
2.2. Composition and importance of the hop alpha acids 54
2.3. Biogenesis of the hop alpha acids 55
2.4. Synthesis of the hop alpha acids 57
2.5 References to Chapter 2 61
Chapter 3. Reduced derivatives of humulone 65
3.1. Dihydrohumulone 65
3.2. Tetrahydrohumulone 66
3.3. Humulohydroquinone-humuloquinone 67
3.4. 4-Deoxyhumulone 69
3.5. 2,6-Bis(3-methylbutyl)-4-(3-methylbutanoyl)resorcinol 71
3.6. 2,4,6-Tris(3-methylbutyl)resorcinol 72
3.7. References to Chapter 3 72
Chapter 4. Oxidized derivatives of humulone 73
4.1. Humulinone 73
4.2. Tricyclodehydro-isohumulone (TCD) 83
4.3. Compound 47 89
4.4. Compound 50 90
4.5. Compound 52 91
4.6. Compound 53 91
4.7 Compound 54 91
4.8. Compound 55 91
4.9. Compound 57 93
4.10. Abeo-isohumulones 94
4.11. Tetronic acid derivative 67 98
4.12. Volatile oxidation products 102
4.13. Latest contributions 104
4.14. References to Chapter 4 105
Chapter 5. The isohumulones 109
5.1 .Structure of the isohumulones 109
5.2. Formation of the isohumulones 123
5.3. Interconversion between isohumulones and humulone 136
5.4. Synthesis of the isohumulones 137
5.5. Importance of the isohumulones 141
5.6. References to Chapter 5 143
Chapter 6. Reduced derivatives of the isohumulones 148
6.1. Dihydro-isohumulones 148
6.2. Tetrahydro-isohumulones 148
6.3. Neohydro-isohumulones and neohydro-isocohumulones 151
6.4. Compound 97 152
6.5. The rho-isohumulones 153
6.6. Compound 107 158
6.7. References to Chapter 6 159
Chapter 7. Oxidized derivatives of the isohumulones 160
7.1. Non-volatile oxidized derivatives 160
7.2. Volatile oxidized derivatives 160
7.3. References to Chapter 7 161
Chapter 8. Transformation and degradation products of the isohumulones 162
8.1. The allo-isohumulones 163
8.2. The hydrated allo-isohumulones 169
8.3. The acetylhumulinic acids 171
8.4. The humulinic acids and derivatives 173
8.5. References to Chapter 8 199
Chapter 9. The anti-isohumulones 201
9.1. Isolation 201
9.2. Nomenclature 201
9.3. Structural proofs 202
9.4. Formation mechanism 204
9.5. Importance of the anti-isohumulones 206
9.6. References to Chapter 9 206
Chapter 10. Degradation and derivatives of the anti-isohumulones 207
10.1. The anti-acetylhumulinic acids 207
10.2. Deacylated derivatives of the anti-isohumulones 209
10.3. Special derivatives of the anti-isohumulones 216
10.4. References to Chapter 10 221
Chapter 11. The beta acids 222
11.1. Structure of the beta acids 222
11.2. Composition of the beta acids 229
11.3. Biogenesis of the beta acids 232
11.4. Synthesis of the beta acids 232
11.5. References to Chapter 11 234
Chapter 12. Reduced derivatives of the beta acids 237
12.1. Hexahydro-beta acids 237
12.2. 4-Deoxy-alpha acids 239
12.3. 4-Deoxytetrahydro-alpha acids 239
12.4. Reduction products of colupulone with zinc : acetic acid : hydrogen chloride 240
12.5. References to Chapter 12 243
Chapter 13. Oxidized derivatives of the beta acids 244
13.1. Oxidation with oxygen or auto-oxidation 244
13.2. Oxidation with chemical oxidants 307
13.3. References to Chapter 13 327
Chapter 14. Derivatives of the beta acids in acidic and in alkaline conditions 331
14.1. Treatment with strong acid 331
14.2. Treatment with weak acid 334
14.3. Treatment with alkali 334
14.4. Treatment with very strong alkali at high temperatures 336
14.5. References to Chapter 14 336
Chapter 15. The analysis of hop and beer bitter acids 337
15.1. Introduction 337
15.2. The analysis of hops and beer bitter acids 337
15.3. Samples to be analysed 338
15.4. Principles of specific alpha and iso-alpha acids analysis 342
15.5. Boiling methods for evaluating hops and hop products 348
15.6. References to Chapter 15 349
Chapter 16. Analysis of alpha acids 351
16.1. Introduction 351
16.2. General problems related to alpha acids analysis 351
16.3. Problems related to the sample preparation 352
16.4. Problems related to the analytical procedure 353
16.5. Practical conductometric alpha acids analysis 357
16.6. Practical analysis of alpha acids by liquid chromatography 359
16.7. Micellar Electrokinetic Capillary Chromatography 370
16.8. Conclusion 370
16.9. References to Chapter 16 371
Chapter 17. Analysis of iso-alpha acids 372
17.1. Introduction 372
17.2. General problems related to iso-alpha acids analysis 372
17.3. Problems related to the sample preparation 374
17.4. Problems related to the analytical procedure 375
17.5. Practical direct photometry of iso-alpha acids 383
17.6. Practical LC analysis of iso-alpha acids 384
17.7. References to Chapter 17 388
Chapter 18. The future of hop chemistry 389
18.1. Introduction 389
18.2. Liquid Chromatography 389
18.3. Specific research possibilities for Liquid Chromatography 390
18.4. Capillary electrophoresis (CE) 399
18.5. Specific problems for CE 399
18.6. Sensor and probe techniques 400
18.7. In conclusion 400
18.8. References to Chapter 18 401
Formula Number Index 402
Formula Index 412
General Index 422