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