Ma Yam Tak. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (leaves 280-299). / Abstracts in English and Chinese. / Thesis Committee: --- p.i / Acknowledgements --- p.ii / Abstract --- p.iii / 摘要 --- p.vi / Content --- p.viii / List of Tables --- p.xvii / List of Figures --- p.xxiv / Abbreviations --- p.xxvi / Chapter Chapter 1: --- Introduction --- p.1 / Chapter 1.1 --- Reactive oxygen species (ROS) --- p.1 / Chapter 1.1.1 --- Definition --- p.1 / Chapter 1.1.2 --- Formation of ROS --- p.2 / Chapter 1.1.2.1 --- Homolysis --- p.2 / Chapter 1.1.2.2 --- Reaction with pre-formed odd-electron species --- p.2 / Chapter 1.1.2.3 --- Electron transfer --- p.3 / Chapter 1.1.2.4 --- Metabolism and cellular functions --- p.3 / Chapter 1.1.3 --- Sources of ROS in human --- p.4 / Chapter 1.1.4 --- Chemistry and Biochemistry of ROS --- p.6 / Chapter 1.1.4.1 --- Superoxide anion radical (O2、) --- p.6 / Chapter 1.1.4.2 --- Hydrogen peroxide (H2O2) --- p.8 / Chapter 1.1.4.3 --- Hydroxyl radical (HO) --- p.9 / Chapter 1.1.5 --- Lipid peroxidation --- p.10 / Chapter 1.2 --- Antioxidants --- p.11 / Chapter 1.2.1 --- Definition --- p.11 / Chapter 1.2.2 --- Mechanism of action --- p.11 / Chapter 1.2.3 --- Natural antioxidants --- p.13 / Chapter 1.2.3.1 --- Endogenous antioxidants --- p.13 / Chapter 1.2.3.2 --- Exogenous antioxidants --- p.14 / Chapter 1.2.4 --- Synthetic antioxidants --- p.15 / Chapter 1.3 --- Oxidative stress --- p.16 / Chapter 1.3.1 --- Balance between ROS and antioxidants --- p.16 / Chapter 1.3.2 --- Diseases associated with oxidative stress --- p.16 / Chapter 1.3.3 --- Beneficial effects of dietary antioxidants towards degenerative diseases --- p.18 / Chapter 1.4 --- Principles of assay --- p.21 / Chapter 1.4.1 --- Evaluation of antioxidant activity --- p.21 / Chapter 1.4.1.1 --- ABTS radical cation scavenging activity --- p.21 / Chapter 1.4.1.2 --- DPPH radical scavenging capacity --- p.21 / Chapter 1.4.1.3 --- p-carotene bleaching assay --- p.22 / Chapter 1.4.1.4 --- Ferric reducing antioxidant power --- p.23 / Chapter 1.4.1.5 --- Hydroxyl radical scavenging activity --- p.23 / Chapter 1.4.2 --- Determination of phenolic content --- p.24 / Chapter 1.4.2.1 --- Folin-Ciocalteu method --- p.24 / Chapter 1.4.2.2 --- Enzymatic method --- p.25 / Chapter 1.4.3 --- Determination of Hydroxymethylfurfural (HMF) --- p.25 / Chapter 1.5 --- Effect of food processing on antioxidant activity --- p.27 / Chapter 1.5.1 --- Blanching --- p.27 / Chapter 1.5.2 --- Drying --- p.29 / Chapter 1.5.2.1 --- Sun-drying or air-drying --- p.29 / Chapter 1.5.2.2 --- Oven-drying --- p.30 / Chapter 1.5.2.3 --- Infrared-drying or microwave-drying --- p.33 / Chapter 1.5.2.4 --- Freeze-drying --- p.34 / Chapter 1.5.3 --- Canning --- p.34 / Chapter 1.5.4 --- General thermal treatment --- p.36 / Chapter 1.5.5 --- Freezing --- p.37 / Chapter 1.6 --- Mushroom antioxidants --- p.44 / Chapter 1.6.1 --- Nutritional information --- p.44 / Chapter 1.6.2 --- Antioxidant activity of edible mushrooms --- p.44 / Chapter 1.6.3 --- Antioxidant components --- p.47 / Chapter 1.7 --- Objectives --- p.50 / Chapter Chapter 2: --- Method development --- p.63 / Chapter 2.1 --- Introduction --- p.63 / Chapter 2.2 --- Materials and method --- p.67 / Chapter 2.2.1 --- Standard preparation --- p.67 / Chapter 2.2.2 --- Preparation of mushroom crude extracts --- p.67 / Chapter 2.2.3 --- Optimization of the assay on mushroom extracts and standards / Chapter 2.2.3.1 --- Volume ratio between various reagents and samples --- p.69 / Chapter 2.2.3.2 --- Reaction kinetics --- p.69 / Chapter 2.2.3.3 --- Comparison of response of phenolic standards to the enzymatic method and the Folin Ciocalteu (FC) method --- p.70 / Chapter 2.2.3.3.1 --- Enzymatic method --- p.70 / Chapter 2.2.3.3.2 --- FC method --- p.70 / Chapter 2.2.4 --- Statistical analysis --- p.71 / Chapter 2.3 --- Results and discussions --- p.75 / Chapter 2.3.1 --- Sample-to-reagent volume ratio --- p.75 / Chapter 2.3.2 --- Reaction kinetics --- p.77 / Chapter 2.3.3 --- Response of phenolic standards to the enzymatic method and FC method --- p.82 / Chapter 2.3.3.1 --- General trends --- p.82 / Chapter 2.3.3.2 --- Mechanism in the response of phenolic standards to the enzymatic reaction --- p.84 / Chapter 2.3.3.3 --- Mechanism in the response of phenolic standards towards the FC method --- p.86 / Chapter 2.3.4 --- Response of interfering compounds to the enzymatic method and the FC method --- p.88 / Chapter 2.3.5 --- Response of mushroom crude extracts to the enzymatic method and the FC method --- p.89 / Chapter 2.4 --- Conclusion --- p.90 / Chapter Chapter 3: --- Mushroom screening --- p.92 / Chapter 3.1 --- Introduction --- p.92 / Chapter 3.1.1 --- Agrocybe aegerita (Aa) --- p.92 / Chapter 3.1.2 --- Volvariella volvacea (Vv) --- p.93 / Chapter 3.1.3 --- Lentinus edodes (Le) --- p.94 / Chapter 3.1.4 --- Agaricus bisporus (Ab) --- p.95 / Chapter 3.1.5 --- Processing need of fresh mushrooms --- p.95 / Chapter 3.1.6 --- Comparison of antioxidant activity of mushrooms --- p.96 / Chapter 3.2 --- Materials and methods --- p.98 / Chapter 3.2.1 --- Sample preparation --- p.98 / Chapter 3.2.2 --- Proximate analysis of the four fresh edible mushrooms --- p.99 / Chapter 3.2.2.1 --- Crude lipid --- p.99 / Chapter 3.2.2.2 --- Crude protein --- p.99 / Chapter 3.2.2.3 --- Ash content --- p.101 / Chapter 3.2.2.4 --- Total dietary fiber (TDF) content --- p.101 / Chapter 3.2.2.5 --- Moisture content --- p.103 / Chapter 3.2.3 --- Sample extraction --- p.103 / Chapter 3.2.4 --- Total phenolic content --- p.103 / Chapter 3.2.5 --- Evaluation of antioxidant activity --- p.104 / Chapter 3.2.5.1 --- ABTS radical cation scavenging activity --- p.104 / Chapter 3.2.5.2 --- DPPH radical scavenging capacity --- p.105 / Chapter 3.2.5.3 --- Ferric Reducing Antioxidant Power --- p.106 / Chapter 3.2.5.4 --- β-carotene bleaching assay --- p.107 / Chapter 3.2.5.5 --- Hydroxyl radical scavenging activity --- p.108 / Chapter 3.2.6 --- Statistical analysis --- p.109 / Chapter 3.3 --- Results and Discussion --- p.110 / Chapter 3.3.1 --- Proximate analysis --- p.111 / Chapter 3.3.2 --- Total phenolic content --- p.112 / Chapter 3.3.3 --- Antioxidant activities --- p.114 / Chapter 3.3.3.1 --- ABTS radical cation scavenging activity --- p.114 / Chapter 3.3.3.2 --- DPPH radical scavenging capacity --- p.115 / Chapter 3.3.3.3 --- Ferric Reducing Antioxidant Power --- p.120 / Chapter 3.3.3.4 --- β-carotene bleaching assay --- p.121 / Chapter 3.3.3.5 --- Hydroxyl radical scavenging activity --- p.124 / Chapter 3.4 --- Correlation between antioxidant activities and total phenolic content --- p.127 / Chapter 3.5 --- Summary --- p.128 / Chapter Chapter 4: --- Effect of thermal processing on mushroom antioxidants --- p.131 / Chapter 4.1 --- Introduction --- p.131 / Chapter 4.1.1 --- General procedures of thermal processing on mushrooms --- p.131 / Chapter 4.1.1.1 --- Canning --- p.136 / Chapter 4.1.1.2 --- Drying --- p.136 / Chapter 4.1.2 --- Previous studies on the effect of thermal processing on mushroom antioxidants --- p.136 / Chapter 4.2 --- Materials and methods --- p.140 / Chapter 4.2.1 --- Thermal processing --- p.140 / Chapter 4.2.1.1 --- Canning --- p.140 / Chapter 4.2.1.2 --- Drying --- p.143 / Chapter 4.2.2 --- Sample preparation --- p.144 / Chapter 4.2.3 --- Sample extraction --- p.145 / Chapter 4.2.4 --- Evaluation of antioxidant activity --- p.145 / Chapter 4.2.5 --- Total phenolic content --- p.146 / Chapter 4.2.6 --- Measurement of Hydromethylfurfural (HMF) --- p.146 / Chapter 4.2.7 --- Statistical analysis --- p.147 / Chapter 4.3 --- Results --- p.148 / Chapter 4.3.1 --- ABTS radical cation scavenging activity --- p.148 / Chapter 4.3.1.1 --- Canning --- p.148 / Chapter 4.3.1.1.1 --- Effect of blanching --- p.148 / Chapter 4.3.1.1.2 --- Effect of sterilization time --- p.149 / Chapter 4.3.1.1.3 --- Effect of addition of vitamin C --- p.149 / Chapter 4.3.1.1.4 --- Effect of storage --- p.151 / Chapter 4.3.1.2 --- Drying --- p.151 / Chapter 4.3.1.2.1 --- Effect of blanching --- p.152 / Chapter 4.3.1.2.2 --- Effect of drying time --- p.153 / Chapter 4.3.1.2.3 --- Effect of drying temperature --- p.154 / Chapter 4.3.1.2.4 --- Effect of storage --- p.155 / Chapter 4.3.2 --- Ferric Reducing Antioxidant Power --- p.165 / Chapter 4.3.2.1 --- Canning --- p.165 / Chapter 4.3.2.1.1 --- Effect of blanching --- p.165 / Chapter 4.3.2.1.2 --- Effect of sterilization time --- p.166 / Chapter 4.3.2.1.3 --- Effect of addition of vitamin C --- p.167 / Chapter 4.3.2.1.4 --- Effect of storage --- p.168 / Chapter 4.3.2.2 --- Drying --- p.169 / Chapter 4.3.2.2.1 --- Effect of blanching --- p.170 / Chapter 4.3.2.2.2 --- Effect of drying time --- p.171 / Chapter 4.3.2.2.3 --- Effect of drying temperature --- p.172 / Chapter 4.3.2.2.4 --- Effect of storage --- p.173 / Chapter 4.3.3 --- β-carotene bleaching assay --- p.182 / Chapter 4.3.3.1 --- Canning --- p.182 / Chapter 4.3.3.1.1 --- Effect of blanching --- p.183 / Chapter 4.3.3.1.2 --- Effect of sterilization time --- p.183 / Chapter 4.3.3.1.3 --- Effect of addition of vitamin C --- p.184 / Chapter 4.3.3.1.4 --- Effect of storage --- p.184 / Chapter 4.3.3.2 --- Drying --- p.185 / Chapter 4.3.3.2.1 --- Effect of blanching --- p.186 / Chapter 4.3.3.2.2 --- Effect of drying time --- p.187 / Chapter 4.3.3.2.3 --- Effect of drying temperature --- p.188 / Chapter 4.3.3.2.4 --- Effect of storage --- p.189 / Chapter 4.3.4 --- Hydroxyl radical scavenging activity --- p.198 / Chapter 4.3.4.1 --- Canning --- p.198 / Chapter 4.3.4.1.1 --- Effect of blanching --- p.198 / Chapter 4.3.4.1.2 --- Effect of sterilization time --- p.199 / Chapter 4.3.4.1.3 --- Effect of addition of vitamin C --- p.200 / Chapter 4.3.4.1.4 --- Effect of storage --- p.201 / Chapter 4.3.4.2 --- Drying --- p.201 / Chapter 4.3.4.2.1 --- Effect of blanching --- p.202 / Chapter 4.3.4.2.2 --- Effect of drying time --- p.203 / Chapter 4.3.4.2.3 --- Effect of drying temperature --- p.203 / Chapter 4.3.4.2.4 --- Effect of storage --- p.204 / Chapter 4.3.5 --- Total phenolic content --- p.214 / Chapter 4.3.5.1 --- Canning --- p.214 / Chapter 4.3.5.1.1 --- Effect of blanching --- p.215 / Chapter 4.3.5.1.2 --- Effect of sterilization time --- p.217 / Chapter 4.3.5.1.3 --- Effect of addition of vitamin C --- p.218 / Chapter 4.3.5.1.4 --- Effect of storage --- p.219 / Chapter 4.3.5.2 --- Drying --- p.223 / Chapter 4.3.5.2.1 --- Effect of blanching --- p.223 / Chapter 4.3.5.2.2 --- Effect of drying time --- p.225 / Chapter 4.3.5.2.3 --- Effect of drying temperature --- p.226 / Chapter 4.3.5.2.4 --- Effect of storage --- p.227 / Chapter 4.3.6 --- The Hydroxymethylfurfural (HMF) content --- p.237 / Chapter 4.3.6.1 --- Canning --- p.237 / Chapter 4.3.6.1.1 --- Effect of blanching --- p.237 / Chapter 4.3.6.1.2 --- Effect of sterilization time --- p.238 / Chapter 4.3.6.1.3 --- Effect of addition of vitamin C --- p.238 / Chapter 4.3.6.1.4 --- Effect of storage --- p.239 / Chapter 4.3.6.2 --- Drying --- p.239 / Chapter 4.3.6.2.1 --- Effect of blanching --- p.239 / Chapter 4.3.6.2.2 --- Effect of drying time --- p.240 / Chapter 4.3.6.2.3 --- Effect of drying temperature --- p.241 / Chapter 4.3.6.2.4 --- Effect of storage --- p.242 / Chapter 4.4 --- Summary --- p.249 / Chapter 4.5 --- Discussion --- p.257 / Chapter 4.5.1 --- Reduction of antioxidant activities in mushrooms by heat treatment --- p.257 / Chapter 4.5.2 --- Effect of blanching --- p.259 / Chapter 4.5.3 --- Effect of sterilization time --- p.260 / Chapter 4.5.4 --- Effect of drying time and temperature --- p.262 / Chapter 4.5.5 --- Effect of addition of vitamin C --- p.263 / Chapter 4.5.6 --- Changes during storage --- p.265 / Chapter 4.5.7 --- Difference in canning and drying --- p.269 / Chapter Chapter 5: --- Conclusions --- p.275 / References --- p.280