Food Frying: Chemistry, Biochemistry, and Safety (Hardcover)

Dedication

About the author

Preface

Acknowledgement

Section 1: Concepts of the Food Frying

Chapter 1 Food Frying: the Concept 1–17

1.1. Introduction 1

1.2. History of Frying 1

1.3. Mechanism of Frying 2

1.3.1. Heat and Mass Transfer 2

1.3.2. Oil Uptake 4

1.3.3. Mechanism of Oil Absorption 5

1.3.3.1. Water Escape and Oil Uptake 5

1.3.3.2. Capillary Pressure and Oil Uptake 6

1.3.3.3. Vapour Condensation and Vacuum Effects 7

1.3.3.4. Adherence and Drainage of Oil 7

1.3.4. Product Properties and Oil Uptake 8

1.3.4.1. Size, Shape and Surface of the Product 8

1.3.4.2. Composition and Density of the Product 8

1.3.5. Frying Oil Properties and Oil Uptake 9

1.3.5.1. Oil Type 9

1.3.5.2. Oil Aging 9

1.3.6. Process Factors 9

1.3.6.1. Pre-Processing Factors Affecting Oil Quality 10

1.3.6.2. Post-Frying Conditions 10

1.3.7. Chemical and Physical Changes of the Frying Medium 10

1.4. Why we Frying Foods? 11

1.5. Key Concepts 11

1.6. References 12

Chapter 2 The Frying Techniques 18–61

2.1. Introduction 18

2.2. Concept of Deep Frying 18

2.3. Tools Used in Frying 19

2.4. Optimised Conditions 20

2.4.1. External Factors 20

2.4.1.1. Accessibility to Oxygen 20

2.4.1.2. Temperature 23

2.4.1.3. Frying Period/Time 24

2.4.1.4. Food Preparation 25

2.4.2. Internal Factors 27

2.4.2.1. Fatty Acid Composition and Distribution 27

2.4.2.2. Antioxidative Minor Compounds 29

2.5. Types of Frying 30

2.5.1. Pan frying 30

2.5.1.1. Quality Characteristics in Pan Frying 31

2.5.2. Vacuum Frying  32

2.5.2.1. Vacuum Frying Systems 32

2.5.2.2. Fried Product Characteristics 34

2.5.2.3. Frying Temperature & Final Oil Content 35

2.5.2.4. Vacuum Pressure & Final Oil Content 36

2.5.2.5. Pre-Treatment & Final Oil Content 36

2.5.2.6. Pressurisation Period and De-Oiling Period 38

2.5.2.7. Vacuum Frying & Product Quality Attributes 39

2.5.3. Air Frying 40

2.5.3.1. Heat and Mass Transfer 41

2.5.3.2. Quality of the Fried Foods 41

2.5.4. Industrial Frying 42

2.5.4.1. Advantages of Industrial Frying 42

2.5.4.2. Quality in Industrial Frying 43

2.6. Tips to Remember During Frying 43

2.7. Choice of Frying 44

2.8. Key Concepts 45

2.9. References 46

Chapter 3 Frying and Culture 62–69

3.1. Introduction 62

3.2. The Common Point 63

3.3. Frying in American Cuisines 63

3.4. Frying in the European Cuisines 64

3.5. Frying in the Asian Cuisines 65

3.6. Frying in the African Cuisines 66

3.7. Frying in the Middle East Cuisines 67

3.8. Key Concepts 67

3.9. References 68

Section 2: Chemistry of Food Frying

Chapter 4 Chemistry of Frying Medium 70–110

4.1. Introduction 70

4.2. Classification and Choice of Frying Medium 71

4.3. Chemistry of Frying Medium 72

4.3.1. Fatty acids & Triacylglycerols 72

4.3.2. Polyphenolic Compounds 74

4.3.3. Hydrocarbons 75

4.3.4. Pigments 75

4.3.5. Sterols 75

4.3.6. Alcohols 76

4.3.7. Tocopherols & Tocotrienols 76

4.3.8. Phospholipids 77

4.3.9. Volatile and Aroma Compounds 77

4.3.10. Importance of Minor Components in Frying 77

4.4. Chemistry of the Lipid Oxidation during Frying 78

4.4.1. Fatty Acid Hydroperoxides 78

4.4.2. Fatty Acid Epoxides 80

4.4.3. Formation of Acrolein 81

4.4.4. Oxidation of Triacylglycerols 81

4.4.5. Polymerisation 82

4.5. Formation of Volatile Products 83

4.5.1. Significance of Volatile Products in Frying 86

4.6. Sterol Oxidation 86

4.7. Tocopherol Oxidation 88

4.8. Formation of Trans Fatty Acids 88

4.9. Techniques for Measuring Lipid Oxidation 89

4.10. Key Concepts 91

4.11. References 91

Chapter 5 Chemistry of Fried Foods 111–160

5.1. Introduction 111

5.2. Carbohydrates 111

5.2.1. Monosaccharides 112

5.2.2. Oligosaccharides 112

5.2.3. Polysaccharides 113

5.3. Amino Acids & Proteins 114

5.4. Lipids 115

5.5. Macro-Molecular Composition 116

5.6. Frying of Carbohydrate Rich Foods 116

5.6.1. Formation of Furans 116

5.6.2. Formation of Acrylamide 119

5.6.3. Formation of Acrolein 121

5.7. Frying of Protein Rich Foods 122

5.7.1. Formation of Heterocyclic Aromatic Amines 122

5.7.2. Polycyclic Aromatic Amines 124

5.7.3. Formation of Acrolein 126

5.8. Frying of Seafood 126

5.8.1. Changes in Carbohydrates 127

5.8.2. Changes in Lipids 128

5.8.3. Changes in Proteins 130

5.8.4. Heterocyclic Aromatic Amines 131

5.8.5. Cholesterol Oxidation 131

5.9. Frying of Vegetables 132

5.9.1. Phenolic Compounds 132

5.9.2. Carotenoids 133

5.9.3. Vitamins 135

5.9.4. Phytosterols 135

5.9.5. Maillard Reaction Products 135

5.10. Physiochemical Characteristics of Fried Foods 136

5.10.1. Oil Contents 136

5.10.2. Colour 136

5.10.3. Texture 137

5.10.4. Moisture Contents 139

5.11. Chemistry for Improving Product Quality 139

5.12. Key Concepts 140

5.13. References 141

Chapter 6 Chemistry of Interactions in Frying 161–190

6.1. Introduction 161

6.2. Factors affecting Frying Medium 162

6.2.1. Temperature & Surface/Volume Ratio 162

6.2.2. Triacylglycerols Composition 163

6.2.3. Moisture Contents 163

6.2.4. Antioxidants 164

6.3. Factors Affecting Frying of Foods 166

6.3.1. Physical Parameters 166

6.3.2. Chemical Parameters 167

6.3.2.1. Vegetable Foods 168

6.3.2.2. Animals Foods 170

6.4. Heat Transfer 171

6.5. Mass Transfer 172

6.6. Nutritional Value Retention 173

6.6.1. Vitamins 173

6.6.2. Carotenoids 173

6.6.3. Phenolic Compounds 173

6.6.4. Fatty acids and Triacylglycerols 174

6.6.5. Other Nutrients 174

6.7. Key Concepts 174

6.8. References 175

Chapter 7 Analysis of Frying 191–250

7.1. Introduction 191

7.2. Analysis of Triacylglycerols 192

7.2.1. Analysis of Oxidized Triacylglycerols 193

7.2.1.1. Thin Layer Chromatography 193

7.2.1.2. High Performance Liquid Chromatography 194

7.2.1.2.1. Normal Phase LC 194

7.2.1.2.2. Reversed Phase LC 195

7.2.1.3. Liquid Chromatography Mass Spectrometry 198

7.2.1.3.1. HPLC-APCI-Mass Spectrometry 198

7.2.1.3.2. HPLC-ESI-Mass Spectrometry 199

7.2.2. Quantification of Oxidized Triacylglycerols 201

7.3. Analysis of Fatty Acids Oxidation Products 202

7.3.1. Quantification of Oxygenated Fatty Acids 204

7.4. Analysis of Sterols Oxidation 206

7.4.1. Analysis of Cholesterols and COPs 206

7.4.1.1. Gas Chromatography 207

7.4.1.2. Liquid Chromatography 208

7.4.2. Analysis of Phytosterols Oxidation 210

7.5. Analysis of Sensory Metabolites 212

7.6. Analysis of Heterocyclic Aromatic Amines 216

7.7. Analysis of Acrylamide 217

7.8. Analysis of Tocopherols 219

7.9. Analysis of Polyphenolic Compounds 220

7.10. Analysis of Other Minor Compounds 220

7.11. Key Concepts 221

7.12. References 222

Section 3: Biochemistry of Food Frying

Chapter 8 Digestion & Absorption of Fried Foods 251–265

8.1. Introduction 251

8.2. Acceptability of Fried Foods 251

8.3. Digestion of Fried Foods 252

8.3.1. In-Vitro Digestion 253

8.3.2. In-Vivo Digestion 254

8.4. Absorption of Fried Foods 255

8.5. Excretion of Fried Foods 257

8.6. Key Concepts 257

8.7. References 258

Chapter 9 Nutrition and Metabolism of Fried Foods 266–295

9.1. Introduction 266

9.2. Metabolism of Fried Lipids 267

9.2.1. Pheno-Typical Alterations of Lipid Metabolism 268

9.2.1.1. TAG Concentrations in Liver and Plasma 268

9.2.1.2. Cholesterol Concentration in Liver and Plasma 270

9.2.1.3. Phospholipids Concentration in Liver and Plasma 271

9.2.1.4. Carnitine Concentration in Liver and Plasma 272

9.2.1.5. Free Fatty Acids & Ketone Bodies in Plasma 272

9.2.2. Molecular Regulators of Lipid Metabolism 272

9.2.3. Evidence for the Activation of PPARα by Oxidized Fat 274

9.3. Metabolism of Fried Proteins 276

9.3.1. Metabolism of Heterocyclic Aromatic Amines 277

9.4. Metabolism of Fried Carbohydrates 279

9.4.1. Metabolism of Acrylamide 279

9.4.2. Metabolism of Furfurals 280

9.5. Metabolism of Other Metabolites 281

9.6. Key Concepts 282

9.7. References 282

Chapter 10 Fried Foods in Health & Diseases 296–315

10.1. Introduction 296

10.2. Fried Foods and Health 297

10.2.1. Frying for Maintaining Health 297

10.2.2. Frying and Health Hazards 298

10.3. Fried Foods and Cancer 299

10.4. Fried Foods and Diabetes 301

10.5. Fried Foods and Cardiovascular Diseases 301

10.5.1. Trans-Fats and Cardiovascular Health           302

10.6. Fried Foods and Aging 303

10.7. Key Concepts 304

10.8. References 304

Section 4: Safety of Food Frying

Chapter 11 Safety Assessment of Food Frying 316–335

11.1. Introduction 316

11.2. Guidelines for the Assessment 316

11.2.1. Assessment Criteria for Used Frying Oil and Frying Fat 316

11.3. Quality Indicators for Used Frying Oils 318

11.4. Physical Assessment 320

11.4.1. Sensory evaluation, Colour, and Foaming 320

11.4.2. Quick Tests for Viscosity and Dielectricity 321

11.5. Chemical Assessment 322

11.5.1. Chemical Quick Tests 322

11.5.2. Near-Infrared Spectroscopy 322

11.5.3. Mass Spectrometry 323

11.6. Evaluation of Fried Foods 323

11.7. The Future of Fried Food Safety 323

11.8. Key Concepts 324

11.9. References 324

Chapter 12 Toxicity of Frying 336–375

12.1. Introduction 336

12.2. Toxicity of Oxidized Triacylglycerols 336

12.3. Toxicity of Acrylamide 337

12.4. Toxicity of Acrolein 339

12.4.1. Toxico-Kinetics and Metabolism 340

12.4.2. General Toxic Effects 341

12.4.3. Acute, Subchronic and Chronic Toxicity 342

12.4.4. Reproduction Toxicity 342

12.4.5. Genotoxicity 343

12.4.5.1. In-vitro Genotoxicity 343

12.4.5.2. In-vivo Genotoxicity 343

12.4.6. DNA Adducts 343

12.4.7. Carcinogenicity 344

12.4.7.1. Epidemiology 345

12.5. Toxicity of Amines & Alcohols 346

12.5.1. Mutagenicity of HAA 346

12.5.2. Carcinogenicity of HAA 347

12.5.3. Risk Assessment 347

12.5.3.1. Daily Intake of HAA 347

12.5.4. Epidemiological Data 349

12.5.4.1. Risk Evaluation 349

12.6. Toxicity of Aldehydes 351

12.6.1. Genotoxicity and Mutagenicity of Furfurals 351

12.6.2. Acute and Sub-chronic Toxicity 352

12.6.3. Carcinogenicity in Animal models 353

12.6.3.1. Intestinal Micro-adenomas 353

12.6.3.2. Colon Pre-Neoplastic Lesions 353

12.6.3.3. Studies with Transgenic Mice 353

12.6.3.4. The NTP Studies 354

12.6.3.5. Studies with SMF 355

12.6.4. Assessment of Carcinogenicity of 5‐HMF 356

12.7. Pro-Oxidants 357

12.8. Disposal Fried Foods 358

12.9. Disposal & Usage of Fried Medium 359

12.9.1. Regeneration of Oils 359

12.9.2. Biodiesel Production 360

12.9.3. Other Uses 360

12.10. Key Concepts 324

12.11. References 324

Chapter 13 Improving the Quality of Fried Foods 376–410

13.1. Introduction 376

13.2. Improving Quality of Fried Foods 376

13.2.1. Pre-treatment of Food 376

13.2.2. Conventional Frying Pre-treatment Methods 378

13.2.2.1. Pre-drying (hot‐air drying) 378

13.2.2.2. Blanching 379

13.2.2.3. Coating 380

13.2.2.4. Osmotic Dehydration 381

13.2.2.5. Freezing Techniques 383

13.2.3. Novel Pre-Treatment Methods 384

13.2.3.1. Infrared Technology 384

13.2.3.2. Microwave Technology 385

13.2.3.3. Ultrasound Technology 387

13.2.3.4. Pulsed Electric Field 388

13.3. Mitigation Strategies for Acrylamide 389

13.3.1. Agronomical Methods 389

13.3.2. Biological Methods 390

13.3.3. Physical Methods 390

13.3.4. Chemical Methods 392

13.4. Reducing Oil Uptake 392

13.5. Fortification 393

13.6. The Role of Natural Antioxidants 393

13.6.1. Tocochromanols 394

13.6.2. Polyphenolic Compounds 395

13.6.3. Phytosterols 396

13.6.4. Squalene 396

13.6.5. Carotenoids 396

13.6.6. Plant Extracts 396

13.7. Packaging of Fried Foods 397

13.8. Quality Control in Frying 398

13.9. Key Concepts 399

13.10. References 399

Chapter 14 The Future of Food Frying 411–416

14.1. Introduction 411

14.2. The Current Strategies 411

14.2.1. Improving Frying 411

14.2.2. Obesity and Fried Foods 411

14.2.3. Diabetes and Cardiovascular Diseases 412

14.2.4. Cancer and Fried Foods 413

14.3. The Future Scenario 413

14.4. The Hurdles 415

14.5. Key Concepts 415

14.6. References 416

15. Index 417-430