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Stabilization of sensitive substances
by antioxidants from summer savory and
encapsulation
Dissertation
zur
Erlangung des Grades
Doktor-Ingenieurin / Doktor-Ingenieur
der
Fakultt fr Maschinenbau
der Ruhr-Universitt Bochum
von
Lenua Gontaru
aus Galai
Bochum 2009
Dissertation eingereicht am: 28.05.2009
Tag der mndlichen Prfung: 21.07.2009
Erster Referent: Prof. Dr.-Ing. E. Weidner
Zweiter Referent: Prof. Dr.-Ing. B. Simandi
I
TABLE OF CONTENT
1. INTRODUCTION ................................................................................................................ 1
2. MANUFACTURING OF ANTIOXIDANTS AND PROCESSING OF SENSITIVE
SUBSTANCES .......................................................................................................................... 3
2.1. GAIN OF ANTIOXIDANTS .................................................................................................. 4
2.1.1. Antioxidants and their mechanism of action ............................................................ 4
2.1.2. Active compounds with antioxidant properties from plants ..................................... 5
2.1.3. Herbs and spices as natural antioxidants .................................................................. 9
2.1.4. Thermal separation techniques ............................................................................... 11
2.2. ENCAPSULATION OF SENSITIVE SUBSTANCES ............................................................... 21
2.1.1. Encapsulated products: structure and release mechanisms .................................... 22
2.2.2. Encapsulation processes ......................................................................................... 23
3. MATERIALS ...................................................................................................................... 29
3.1. SUMMER SAVORY (SATUREJA HORTENSIS L.) ............................................................... 29
3.2. SOYBEAN OIL ................................................................................................................. 34
3.3. POLYETHYLENE GLYCOL 6000 ..................................................................................... 35
3.4. CARBON DIOXIDE .......................................................................................................... 35
3.5. ORGANIC SOLVENTS ...................................................................................................... 36
4. EXPERIMENTAL METHODS, CHARACTERISATION AND ANALYSIS ............ 37
4.1. SEPARATION AND CHARACTERIZATION OF RAW MATERIAL ........................................ 37
4.1.1. Determination of moisture content ......................................................................... 37
4.1.2. Sieving .................................................................................................................... 37
4.1.3. Hydro-distillation ................................................................................................... 37
4.1.4. Soxhlet extraction ................................................................................................... 38
4.1.5. Pilot scale extraction ............................................................................................... 39
4.1.6. Supercritical fluid extraction .................................................................................. 40
4.2. ENCAPSULATION ........................................................................................................... 42
4.2.1. PGSS process .......................................................................................................... 42
4.2.2. Particle morphology ............................................................................................... 44
4.2.3. Particle size ............................................................................................................. 45
4.3. ANALYTICAL METHODS ................................................................................................ 46
4.3.1. Analysis of volatile compounds ............................................................................. 46
4.3.2. Determination of the antioxidant activity ............................................................... 47
4.3.2.1. 2,2-Diphenyl-1-picrylhydrazyl (DPPH assay) ................................................ 47
4.3.2.2. Rancimat method ............................................................................................. 48
II Table of content
4.3.3. Total polyphenol compound analysis ..................................................................... 48
4.3.4. Total flavonoid compound analysis ....................................................................... 49
4.3.5. Statistical analysis .................................................................................................. 49
4.3.6. Identification and quantification of rosmarinic acid and caffeic acid .................... 49
4.3.7. Investigation of oxidation of soybean oil ............................................................... 50
4.3.8. Peroxide value ........................................................................................................ 51
4.3.9. Acid value .............................................................................................................. 51
5. RESULTS AND DISCUSSION......................................................................................... 53
5.1. EXTRACTION ................................................................................................................. 53
5.1.1. Characterization of plant materials ........................................................................ 53
5.1.2. Selection of the solvent .......................................................................................... 54
5.1.2.1. Soxhlet extraction ............................................................................................ 54
5.1.2.2. Supercritical fluid extraction ........................................................................... 55
5.1.3. Quantitative and qualitative determination of volatile compounds ....................... 59
5.1.4. Antioxidant activity in polar and non polar system ............................................... 60
5.1.4.1. DPPH method .................................................................................................. 60
5.1.4.2. Rancimat test ................................................................................................... 64
5.1.5. Total polyphenol and total flavonoid content ........................................................ 66
5.1.6. Active compounds with antioxidant properties ...................................................... 70
5.1.7. Conclusion .............................................................................................................. 74
5.1.8 Application of SFE modeling .................................................................................. 76
5.2. ENCAPSULATION OF OIL ............................................................................................... 81
5.2.1. Preliminary tests ..................................................................................................... 81
5.2.1.1. Influence of temperature on stability of soybean oil ....................................... 81
5.2.1.2. Influence of pressure on particle morphology ................................................. 81
5.2.1.3. Influence of concentration of core material .................................................... 82
5.2.2. Stability measurements .......................................................................................... 84
5.2.2.1. Soybean oil encapsulated in PEG 6000 ........................................................... 84
5.2.2.2. Soybean oil encapsulated with natural extracts in PEG 6000 ......................... 86
5.2.2.3. Conclusion ....................................................................................................... 89
6. SUMMARY AND OUTLOOK ......................................................................................... 91
7. ABBREVIATION AND NOTATION .............................................................................. 94
8. REFERENCES ................................................................................................................... 98
9. APPENDIX ....................................................................................................................... 107