Biotechnology in Flavor Production

Throughout history, human beings have sought ways to enhance the flavor of the foods they eat. In the 21st century, biotechnology plays an important role in the flavor improvement of many types of foods. This book covers many of the biotechnological approaches currently being applied to flavor enhancement. The contribution of microbial metabolism to flavor development in fermented beverages and dairy products has been exploited for thousands of years, but the recent availability of whole genome sequences of the yeasts and bacteria involved in these processes is stimulating targeted approaches to flavor enhancement.

Chapters discuss recent developments in the flavor modification of wine, beer, and dairy products through the manipulation of the microbial species involved. Biotechnological approaches to the production of specific flavor molecules in microbes and plant tissue cultures, and the challenges that have been encountered, are also covered, along with the metabolic engineering of food crops for flavor enhancement - also a current area of research. Biotechnology is also being applied to crop breeding through marker-assisted selection for important traits, including flavor, and the book looks at the application of the biotechnological approach to breeding for enhanced flavor in rice, apple, and basil. These techniques are subject to governmental regulation, and this is addressed in a dedicated chapter.

This updated second edition features five brand new chapters, and the topics covered in the book will be of interest to those in the flavor and food industries as well as to academic researchers interested in flavors.

Dr Daphna Havkin-Frenkel, Department of Plant Pathology and Biology, Rutgers University, New Brunswick, New Jersey and Director of Research and Development, Bakto Flavors LLC, New Jersey.

Dr Nativ Dudai, Researcher, Newe Ya'ar Research Center, The Agricultural Research Organization of Israel, Ramat Yishay, Israel.

Contributors xi

Preface xv

Chapter 1 The flavor of citrus fruit 1
Ron Porat, Sophie Deterre, Pierre Giampaoli and Anne Plotto

Introduction 1

Taste components of citrus fruit 3

Sugars 5

Acids 6

Bitter compounds 6

Aroma compounds of citrus fruit 8

Terpene hydrocarbons 9

Aldehydes 10

Alcohols 11

Esters 11

Ketones 11

Other volatiles 12

Citrus genes involved in flavor production 12

The unique flavor of different citrus species 13

The flavor of oranges 14

The flavor of mandarins 14

The flavor of grapefruit 15

The flavor of lemons 16

Accumulation of off-flavors in fresh citrus fruit during postharvest storage 17

Flavor of citrus essential oils 19

Acknowledgments 24

References 24

Chapter 2 Aroma as a factor in the breeding process of fresh herbs – the case of basil 32
Nativ Dudai and Faith C. Belanger

The importance of selecting for aroma in breeding of aromatic plants 32

The importance of genetic factors regarding the essential oil composition in aromatic plants 32

Sweet basil and the Ocimum genus 34

Uses of sweet basil 34

The chemistry of the aroma factors of plants: the essential oil 36

Essential oil profiles of common commercial basil varieties 36

Comparison of chemical analysis methods 41

Variation of the volatile compound composition within the plant 43

Variation of aroma compounds within cultivars and the potential for selection 45

Biosynthetic pathways of basil aroma components 47

Inheritance of aroma compounds in basil 50

Interspecific hybridization among Ocimum species 52

Applications of biotechnology-based approaches to modification of basil aroma 53

References 54

Chapter 3 Novel yeast strains as tools for adjusting the flavor of fermented beverages to market specifications 62
Jan H. Swiegers, Sofie M.G. Saerens and Isak S. Pretorius

Introduction 62

Wine 63

Beer 63

Saké 64

Wine, beer, and saké yeasts 64

Wine yeasts 65

Beer yeasts 67

Saké yeasts 67

Acids 69

Non-volatile acids 69

Volatile acids 72

Alcohols 74

Ethanol 74

Glycerol 76

Higher alcohols 78

Esters 83

Carbonyl compounds 91

Acetaldehyde 91

Diacetyl 93

Volatile phenols 95

Sulfur compounds 98

Sulfides 98

Mercaptans 102

Thiols 102

Monoterpenoids 106

Conclusion 109

References 109

Chapter 4 Biotechnology of flavor formation in fermented dairy products 133
Balasubramanian Ganesan and Bart C. Weimer

Introduction 133

Biochemistry of dairy fermentations 135

Biotechnology and flavor 138

Flavor production from bacteria 147

Comparative genomics of flavor production 149

Expression and metabolite analysis 154

Predictive bioinformatics 155

Non-culturable lactococci 156

Translation of omics to biotechnology 156

Conclusion 158

References 158

Chapter 5 Biotechnological production of vanillin 165
Daphna Havkin-Frenkel and Faith C. Belanger

Introduction 165

Biosynthesis of vanillin 168

Natural occurrence of vanillin 168

Site of vanillin production in vanilla beans 168

Vanillin biosynthetic pathway in Vanilla planifolia 170

Production of vanillin by biotechnology 171

Introduction 171

Use of microorganisms 172

Use of plant tissue culture 177

Use of enzymes 177

Use of physical and mild chemistry methods 181

Synthetic vanillin 182

Vanillin from vanilla beans 182

Regulations 183

Conclusions and future outlook 185

References 186

Chapter 6 Plant cell culture as a source of valuable chemicals 193
Chee-Kok Chin

Introduction 193

Establishment of callus culture 194

Initiation and maintenance of cell culture 197

Production of valuable chemicals by cultured plant cells 198

Metabolic engineering to improve chemical production 204

Concluding remarks 205

References 205

Chapter 7 Increasing the methional content in potato through biotechnology 211
Rong Di

Flavor compound methional in foods 211

Formation of methional 212

Synthesis of Met in plants 213

Biotechnology to enhance Met and methional 214

References 217

Chapter 8 Flavor development in rice 221
Louis M.T. Bradbury, Robert J. Henry and Daniel L.E. Waters

Introduction 221

Old flavors of rice 221

Rice texture 223

Fragrant rice 224

The chemistry of rice fragrance 227

The genetics of rice fragrance 228

BAD enzymes and 2AP synthesis 233

The future 237

References 237

Chapter 9 Tomato aroma: biochemistry and biotechnology 243
Rachel Davidovich-Rikanati, Yaron Sitrit, Yaakov Tadmor, Eran Pichersky, Natalia Dudareva and Efraim Lewinsohn

The major aroma impact volatiles in tomato and their biosynthetic pathways 243

Biosynthesis of tomato volatiles 244

Degradation of fatty acids 244

Volatiles derived from amino acids 246

Terpenes 248

Carotenoid pigmentation affects the flavor and volatile composition of tomato fruit 250

Genetic engineering of tomato aroma 253

Contribution of “omics” to improving our understanding of aroma biosynthesis and perception 256

Conclusion 258

Acknowledgment 258

References 258

Chapter 10 Breeding and biotechnology for flavor development in apple (Malus × domestica Borkh.) 264
Susan K. Brown

Quality 265

Apple volatiles 265

Ester compounds and ester biosynthesis 266

Measurement techniques 266

Varietal and developmental differences 267

Effect of storage 268

Effect of processing 269

Effect of 1-methylcyclopropene treatment 270

Hypoxia 270

Gene isolation 271

Genetic studies, linkage maps, and marker-assisted selection 271

ESTs 272

Transgenic approaches 273

Ethylene production and softening (ACS–ACO) 274

Consumer perceptions and sensory testing 274

References 275

Chapter 11 Biosynthesis and perception of melon aroma 281
Itay Gonda, Yosef Burger, Arthur A. Schaffer, Mwafaq Ibdah, Ya’akov Tadmor, Nurit Katzir, Aaron Fait and Efraim Lewinsohn

Introduction 281

Volatile composition of melon fruit 283

Odor perception 288

Biosynthesis of melon aroma volatiles 292

Terpenoids 292

Fatty acid-derived volatile aldehydes 293

Amino acid-derived aroma compounds 294

Formation of volatile alcohols from volatile aldehydes 296

Formation of volatile esters from volatile alcohols 297

The interphase between volatile and non-volatile metabolites 298

Changes of volatile profiles in transgenic melons inhibited in ethylene production 299

Concluding remarks 299

References 300

Index 307

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