Wheat Antioxidants

Contributors xi

CHAPTER 1 OVERVIEW AND PROSPECTIVE 1

1.1 Introduction 1

1.2 Antioxidant Properties of Wheat Grain 2

1.3 Other Biological Activities of Wheat Antioxidants 3

1.4 Wheat Antioxidants: Opportunities and Challenges 5

CHAPTER 2 ANTIOXIDANT PROPERTIES OF WHEAT GRAIN AND ITS FRACTIONS 7

2.1 Sample Preparation 8

2.2 Total Phenolic Content (TPC) and Total Antioxidant Capacity (TAC) of Wheat Fractions 8

2.3 Iron(II)-Chelating Activity of Wheat Fractions 11

2.4 Oxygen Radical Absorbance Capacity (ORAC) of Wheat Fractions 13

2.5 Inhibition of Photochemiluminescence (PCL) by Wheat Fractions 14

2.6 Effect of Milling and Pearling of Wheat on Inhibition of Low-Density Lipoprotein (LDL) Oxidation 17

2.7 Influence of Milling and Pearling on Homediated Supercoiled DNA Scission by Wheat 19

2.8 Conclusions 20

CHAPTER 3 EFFECTS OF GENOTYPE, ENVIRONMENT AND GENOTYPE • ENVIRONMENT INTERACTION ON THE ANTIOXIDANT PROPERTIES OF WHEAT 24

3.1 Introduction 24

3.2 Genotype Effects 26

3.2.1 Total Phenolic Content 27

3.2.2 Phenolic Acid Composition 28

3.2.3 DPPH Scavenging Capacity 31

3.2.4 Superoxide Scavenging Capacities 31

3.2.5 Peroxyl Radical Scavenging Capacities 32

3.3 Environment Effects 32

3.4 Genotype by Environment Interaction Effects 33

3.5 Relative Contribution of G, E, and G • E Effects to Total Variation 35

3.6 Concluding Remarks 37

CHAPTER 4 CAROTENOID, TOCOPHEROL, LIGNAN, FLAVONOID, AND PHYTOSTEROL COMPOSITIONS OF WHEAT GRAIN AND ITS FRACTIONS 42

4.1 Introduction 42

4.2 Phytochemical Composition of Wheat 43

4.2.1 Polyphenols (Lignans, Flavonoids) 43

4.2.2 Carotenoids 46

4.2.3 Tocopherols and Tocotrienols 48

4.2.4 Phytosterols and Phytostanols 49

4.2.5 Antioxidant Activities and Health Benefits 49

4.3 Conclusion 52

CHAPTER 5 ANTIOXIDANT PROPERTIES OF WHEAT PHENOLIC ACIDS 54

5.1 Introduction 54

5.2 Phenolic Acid Contents in Wheat Grain and Fractions 54

5.3 Free Radical Scavenging Capacity of Wheat Phenolic Acids 59

5.4 Inhibitory Effect of Wheat Phenolic Acids on Lipid Peroxidation 64

5.5 Chelating Properties of Wheat Phenolic Acids 66

5.6 Other Antioxidant Activities of Wheat Phenolic Acids 66

5.7 Structure–Activity Relationship of Wheat Phenolic Acids 70

CHAPTER 6 EFFECTS OF POSTHARVEST TREATMENTS, FOOD FORMULATION, AND PROCESSING CONDITIONS ON WHEAT ANTIOXIDANT PROPERTIES 73

6.1 Introduction 73

6.2 Wheat Postharvest Treatments 74

6.2.1 Wheat Flour Milling 74

6.2.2 Pearling or Debranning 76

6.2.3 Storage of Wheat and Wheat Products 77

6.2.4 Other Postharvest Treatments 78

6.3 Food Formulations 79

6.4 Food Heat Processing 82

6.5 Summary 86

CHAPTER 7 ANTIOXIDANT PROPERTIES OF WHEAT-BASED BREAKFAST FOODS 88

7.1 Introduction 88

7.2 Whole Grains for Health & Wellness 88

7.3 Grains Classification and Consumption 89

7.4 Wheat Types, Morphology, and Composition 90

7.5 Role of Antioxidants in Wheat and Other Cereal Grains 90

7.6 Wheat Milling and Distribution of Antioxidants 91

7.7 Wheat-Based Breakfast Foods 92

7.8 Breakfast Meal Consumption and Demographics 92

7.9 Antioxidants in RTE Breakfast Cereals 93

7.10 Antioxidants and Bread Making 95

7.11 Conclusion 96

CHAPTER 8 EFFECTS OF EXTRACTION METHOD AND CONDITIONS ON WHEAT ANTIOXIDANT ACTIVITY ESTIMATION 100

8.1 Introduction 100

8.2 Extraction Methods and Conditions 101

8.2.1 Effects of Extraction Method 105

8.2.2 Effects of Extraction Conditions 106

8.3 General Considerations for Sample Preparation and Extraction 113

8.4 Extraction Condition Recommendations for Wheat Antioxidant Property Estimation 114

CHAPTER 9 METHODS FOR ANTIOXIDANT CAPACITY ESTIMATION OF WHEAT AND WHEAT-BASED FOOD PRODUCTS 118

9.1 Introduction 118

9.2 DPPH Radical Scavenging Capacity Assay 120

9.2.1 Principles and Background 120

9.2.2 Materials and Solutions Preparation 121

9.2.3 Discussion 124

9.3 ABTS Cation Radical (ABTS_+) Scavenging Capacity Assay 125

9.3.1 Principles and Background 125

9.3.2 Materials and Solutions Preparation 126

9.3.3 Measuring Procedure 127

9.3.4 Calculations 127

9.3.5 Discussion 128

9.4 Superoxide Anion Radical (O2__) Scavenging Capacity Assay 130

9.4.1 Principles and Background 130

9.4.2 Materials and Solutions Preparation 131

9.4.3 Procedure 131

9.4.4 Calculations 131

9.4.5 Discussion 132

9.5 Oxygen Radical Absorbing Capacity (ORAC) Assay 133

9.5.1 Principles and Background 133

9.5.2 Materials and Solutions Preparation 134

9.5.3 Calculations 135

9.5.4 Discussion 136

9.6 Hydroxyl Radical (_OH) Scavenging Capacity (HOSC) Assay for Hydrophilic Antioxidants 138

9.6.1 Principles and Background 138

9.6.2 Materials and Solutions Preparation 139

9.6.3 Calculations 140

9.6.4 Discussion 141

9.6.5 Other Reported Methods for Hydroxyl Radical Scavenging Capacity Estimation 142

9.7 Hydroxyl Radical Scavenging Capacity Assay for Lipophilic Antioxidants Using ESR 143

9.7.1 Principles and Background 143

9.7.2 Materials and Solutions Preparation 144

9.7.3 Procedure 144

9.7.4 ESR Parameters 144

9.7.5 Calculations 145

9.7.6 Discussion 146

9.8 Total Phenolic Contents Assay Using the Folin–Ciocalteu Reagent 147

9.8.1 Principles and Background 147

9.8.2 Procedure 148

9.8.3 Calculations 149

9.8.4 Discussion 149

9.9 Iron(II) Chelating Capacity Assay 150

9.9.1 Principles and Background 150

9.9.2 Procedure 153

9.9.3 Calculations 154

9.9.4 Discussion 154

9.10 Copper(II) Chelating Capacity Assay 155

9.10.1 Principles and Background 155

9.10.2 Materials and Solutions Preparation 156

9.10.3 Procedure 156

9.10.4 ESR Parameters 156

9.10.5 Discussion 158

9.11 Lipid Peroxidation Inhibition Assay (OSI) 158

9.11.1 Principles and Background 158

9.11.2 Results 160

9.11.3 Discussion 160

9.12 Low-Density Lipoprotein (LDL) Peroxidation Inhibition Assay 162

9.12.1 Principles and Background 162

9.12.2 Discussion 165

9.13 Conclusions 166

CHAPTER 10 APPLICATION OF ESR IN WHEAT ANTIOXIDANT DETERMINATION 173

10.1 Introduction 173

10.2 The Principles of ESR 174

10.3 The Application of ESR in Food Systems 176

10.4 ESR Determination of Wheat Antioxidants 179

10.4.1 Free Radical Scavenging Capacities of Wheat Antioxidants 179

10.4.2 Chelating Activity Against Cu2+ 184

10.4.3 Effects of Wheat Antioxidants on Lipid Peroxidation in Liposomes 185

CHAPTER 11 ANALYSIS OF TOCOPHEROLS AND CAROTENOIDS IN WHEAT MATERIALS USING LIQUID CHROMATOGRAPHY–MASS SPECTROMETRY TECHNOLOGY 190

11.1 Introduction 190

11.2 Terminology 193

11.3 Analysis of Tocopherols and Carotenoids by LC-MS Technology 193

11.3.1 Liquid–Liquid Extraction 194

11.3.2 Chromatographic Separation 197

11.3.3 LC–MS Interfaces and MS Detection 201

11.4 Summary 204

CHAPTER 12 QUANTIFICATION OF PHENOLIC ACIDS IN WHEAT AND WHEAT-BASED PRODUCTS 208

12.1 Introduction 208

12.2 Background 209

12.3 Chemicals and Equipments 209

12.4 Methods 210

12.4.1 Sample Preparation 1 210

12.4.2 Sample Preparation 2 According to the Protocol Reported by Kim et al. (Fig. 12.2) 211

12.4.3 HPLC Separation and Determination 213

12.5 Discussion 213

CHAPTER 13 EFFECTS OF WHEAT ON NORMAL INTESTINE 219

13.1 Introduction 219

13.2 Wheat Component Effects on Normal Intestinal Epithelial Cells in vitro 220

13.2.1 Background Information 220

13.2.2 Effects of Wheat Bran Extract on IEC-6 Cell Proliferation 222

13.2.3 Ferulic Acid and IEC-6 Cell Proliferation 224

13.3 Discussion 232

13.4 Conclusion 234

CHAPTER 14 WHEAT ANTIOXIDANTS AND CHOLESTEROL METABOLISM 236

14.1 Introduction 336

14.2 Wheat Antioxidants 236

14.2.1 Phenolic Acids 237

14.2.2 Carotenoids 237

14.2.3 Tocopherols 237

14.3 Wheat Antioxidant Properties 238

14.4 Cholesterol Homeostasis 239

14.5 Effects of Wheat Antioxidants on Cholesterol Metabolism 240

14.6 Summary 241

CHAPTER 15 WHEAT ANTIOXIDANT BIOAVAILABILITY 244

15.1 Introduction 244

15.2 Absorption Characteristics of Fluorescein In Vitro 245

15.3 Absorption Characteristics of Phenolic Acid In Vitro 247

15.3.1 FA and PCA 247

15.3.2 CA, CLA, GA, and RA 248

15.3.3 Artepillin C (AC) 249

15.4 Absorption Efficiency and Bioavailability of Phenolic Acid in Rats 251

15.5 Absorption Characteristics of Colonic Metabolites of Poorly Absorbed Polyphenols In Vitro 253

15.6 Current Knowledge and Status of the MCT-Mediated Transport System 256

15.6.1 Gastric Absorption 256

15.6.2 MCT Subtype Responsible for Transport of PAs and Microbial Metabolites of Polyphenols 256

15.6.3 Concept of Metabonutrients 257

15.7 Overview of Absorption and Bioavailability of Wheat Antioxidants: Future Studies 258

15.7.1 SRA, SPA, VA and PBA 258

15.7.2 Free, Soluble Conjugate, and Insoluble Bound PAs in Wheat 259

CHAPTER 16 WHEAT LIGNANS: PROMISING CANCER PREVENTIVE AGENTS 264

16.1 Introduction 264

16.2 Lignans and Cancer Prevention 266

16.2.1 Epidemiological and Clinical Studies 267

16.2.2 Experimental Animal Studies 267

16.3 Plausible Mechanisms of Lignans for Cancer Prevention 268

INDEX