Title Page
Contents
Abstract 13
Chapter 1. Overall Introduction 14
1.1. Biorefinery 14
1.2. Agriculture residues 15
1.3. Luteolin 17
1.4. Dilute acid hydrolysis 20
1.5. Xylitol 24
1.6. Objectives 25
Chapter 2. Optimization of the Luteolin Recovery Process from Peanut Shells 27
2.1. Materials and methods 27
2.1.1. Materials 27
2.1.2. Extraction procedure for solvent selection 28
2.1.3. Experimental design for extraction optimization 28
2.1.4. Analytical methods 30
2.2. Results and discussion 36
2.2.1. Effect of solvent type on the luteolin recovery 36
2.2.2. Optimization of luteolin recovery conditions 38
2.2.3. Bioactive assessment of peanut shells extracts 50
2.2.4. Carbohydrate composition of peanut shells and the residues after luteolin extraction 55
2.2.5. Process evaluation of luteolin recovery from peanut shells 58
2.3. Conclusions 62
Chapter 3. Process Optimization of Xylose Production from Extracted Peanut Shells by Dilute Acid Hydrolysis 63
3.1. Materials and methods 63
3.1.1. Materials 63
3.1.2. Dilute acid hydrolysis by sulfuric acid reagent with various concentrations 64
3.1.3. Xylitol production with fermentation inhibitors 64
3.1.4. Experimental design for acid hydrolysis condition optimization 65
3.1.5. High performance liquid chromatography analysis 66
3.2. Results and discussion 68
3.2.1. Experimental design for dilute acid hydrolysis including fermentation inhibitory effects 68
3.2.2. Optimization of reaction conditions for dilute acid hydrolysis 76
3.3. Conclusions 93
Chapter 4. Xylitol Fermentation Using Extracted Peanut Shells Hydrolysates and Evaluation of Overall Process 94
4.1. Materials and methods 94
4.1.1. Materials 94
4.1.2. Preparation of extracted peanut shells hydrolysates 94
4.1.3. Xylitol fermentation using extracted peanut shells hydrolysates 95
4.1.4. High performance liquid chromatography analysis 95
4.2. Results and discussion 96
4.2.1. Xylitol fermentation using extracted peanut shells hydrolysates 96
4.2.2. Overall mass balance for luteolin and xylitol production 99
4.3. Conclusions 101
Chapter 5. Overall Conclusions 102
References 107
국문요약 118
Table 2.1. Coded levels and range of variables for luteolin extraction experimental design 29
Table 2.2. Predicted and experimental results of luteolin recovery yield from peanut shells based on designed luteolin recovery conditions 39
Table 2.3. Analysis of variance of the regression model for luteolin recovery yield 42
Table 2.4. Solutions for optimization with luteolin yield of 100% 46
Table 2.5. Predicted and experimental responses for validation of predictive equation for luteolin recovery within the designed range 48
Table 2.6. Quantification of bioactive compounds in peanut shells extracts 51
Table 2.7. Evaluation of antioxidant and anti-elastase activity of peanut shells extracts 54
Table 2.8. The carbohydrate composition of untreated and extracted peanut shells 56
Table 2.9. Summary of luteolin extraction process from various biomass 61
Table 3.1. Coded levels and range of variables for dilute H₂SO₄ hydrolysis experimental design 67
Table 3.2. Chemical composition in extracted peanut shells hydrolysates using acid reagent of various concentrations 70
Table 3.3. Predicted and experimental values for the production of xylose and acetic acid from extracted peanut shells 77
Table 3.4. Analysis of variance of full quadratic model for xylose production 81
Table 3.5. Analysis of variance of full quadratic model for acetic acid production 82
Table 3.6. Analysis of variance of reduced quadratic model for xylose production 85
Table 3.7. Analysis of variance of reduced quadratic model for acetic acid production 86
Table 3.8. Predicted and experimental xylose and acetic acid production under the optimal conditions suggested by the developed model through numerical optimization 92
Figure 1.1. Chemical structure of luteolin. 19
Figure 1.2. Difference between dilute acid hydrolysis and dilute acid pretreatment. 22
Figure 1.3. Lignocellulosic biomass structure and fermentation inhibitors formed after acid hydrolysis. 23
Figure 1.4. Schematic diagram of the overall biorefinery platform. 26
Figure 2.1. Luteolin content recovered from peanut shells using various solvents. The results were expressed as luteolin content (mg/g-biomass),... 37
Figure 2.2. Response surface plots representing the effects of each variable on luteolin yield. The effects of reaction temperature and reaction time (a), reaction temperature and MeOH concentration (b), and reaction time and MeOH... 44
Figure 2.3. Correlation analysis of reaction temperature and MeOH concentration for the design of a model for maximal luteolin recovery from... 49
Figure 2.4. Scanning electron micrographs of untreated peanut shells (a) and extracted peanut shells (b). 57
Figure 2.5. Schematic diagram of the mass balance in the biorefinery platform of peanut shells including luteolin recovery. 59
Figure 3.1. Relative changes in cell growth and xylitol production according to acetic acid concentration. As a control, a medium containing xylose as a... 73
Figure 3.2. Relative changes in cell growth and xylitol production according to acetic acid concentration. As a control, a medium containing xylose as a... 75
Figure 3.3. Response surface plots representing the effects of each variable on xylose production. The effects of reaction time and H₂SO₄ concentration (a), reaction time and biomass loading (b), and H₂SO₄ concentration and biomass loading (c). 88
Figure 3.4. Response surface plots representing the effects of each variable on acetic acid production. The effects of reaction time and H₂SO₄ concentration (a), reaction time and biomass loading (b), and H₂SO₄ concentration and biomass... 90
Figure 4.1. Profiles of xylitol fermentation by Candida tropicalis. Red up-triangles, xylose concentration in ePSH medium; red empty up-triangles,... 98
Figure 4.2. Mass balance of peanut shells to bioproducts based on 1,000 kg peanut. 100
Figure 5.1. Graphical summary on the development of luteolin recovery process. 104
Figure 5.2. Graphical summary on the development of xylose recovery process. 105
Figure 5.3. Graphical summary on the fermentation for xylitol production using extracted peanut shells hydrolysates. 106