Preface

Sex, smoke, and spirits: these three nouns are associated with acts of pleasure and indulgence but can equally invoke feelings of impropriety or abstention in some people and certain cultures. In terms of human evolution, however, each word signifies an essential element in the survival and procreation of our species during its conspecific and environmental interactions. The importance of sex from a biological perspective need not be elaborated on here, but the associated pleasurable and emotional aspects played critical roles in the creation of societal structures, cohabitation, and the evolution of human relationships. Smoke from wildfires would elicit fear and cause flight, but in a different context it was an intrinsic part of essential fire used for cooking, warmth and thereby survival. And spirits (alcohol) was encountered naturally as a byproduct in fermenting fruits but was also actively exploited to preserve foods and later purposefully produced for consumption; distillation has even recently been posited as the primary driver for early nomadic peoples to become settlers ( 1). Sex, smoke, and spirits are similarly integral aspects of many cultural celebrations and rites of passage, both religious and secular, and all have been invoked in some way or other in ritualistic or spiritual observances to connect with a creator or for mental transcendence.

Our evolutionary interactions with these three primeval phenomena have laid the foundations for their societal importance today, with their influences seemingly ingrained in our collective psyche, both positively and negatively. Contemporarily, sex, smoke, and spirits are at the forefront of consumerism and marketing. Sex sells. The smoke (tobacco) and spirits (alcohol) industries are behemoths of consumer goods, primarily geared toward pleasure and indulgence. So, how does chemistry play a role? If you have picked up this book with the hope of reading a romantic thriller, then prepare to be disappointed; but if applied chemistry turns your knobs, then you will be rewarded with a compendium of cutting-edge scientific research centering on the topics of smoke, sex, and spirits.

The contributions to this book are drawn from three symposia organized under the auspices of the Division of Agriculture and Food Chemistry (AGFD) of the American Chemical Society (ACS), held at the 255^th ACS National Meeting that took place from March 18 - 22, 2018 in New Orleans, LA, USA. These symposia were:

• “Chemistry of Sex”, organized by Terry E. Acree, John W. Finley, Stephen J. Toth, Michael H. Tunick, Kathryn. D. Deibler, and Alyson E. Mitchell;

• “Up in Smoke: Chemistry of Smoky Odors in Food & the Environment”, organized by Jonathan D. Beauchamp, Brian D. Guthrie, and Andrea Buettner; and

• “Chemistry of Spirits”, organized by Keith R. Cadwallader, Michael Granvogl, and Michael. C. Qian.

While seemingly disparate topics, discussions between the session organizers during the conference identified many commonalities: the chemistries across these areas represent significant challenges that require the development of new methodologies applied in creative ways. Thus, besides the cultural and societal links between sex, smoke, and spirits, these emerging methods, approaches, and applications are the unifying elements underpinning this book.

Sex and relationships play an implicit role in human well-being, and consumer products are often associated or marketed with connotations toward sex and arousal. The first section of this book contains chapters on topics concerning the chemical origins of attraction, behavior, and pleasure. Fragrance and certain foods, such as chocolate, are well known to drive attraction, emotion, and craving. While psychologists have studied these in great detail, the complete picture of their chemical nature and psychological drivers are still emerging. These are of great importance, especially for fragrance providers, since these are critical determinants of product value. The individual chapters of the sex section include: a report on the chemical basis of perceived fragrance pleasantness and the related molecular structures, stereochemistry, chirality, and other molecular descriptors; a presentation of novel data exploring interpersonal relationships using experimental design theory and statistical models; and a review of the chemistry of chocolate – often considered an aphrodisiac – and its relationship with the consumer in terms of its constituent aroma compounds.

Over the course of history, humans have had significant positive and negative interactions with fire and smoke. Smoke and fire find their way into many human rituals and cuisines. The middle section of this book contains chapters that focus on the complex chemistries and sensory perceptions associated with our interactions with smoke and smoky foods. The smoke chapters include: a review of the chemical structure-to-smoky odor relationships in the perception of smoky odors; an exploration of the specific chemical reactions that occur during wood pyrolysis and impart the characteristic flavors on charcoal-grilled foods; a report on a novel zeolite filter that removes potentially harmful compounds while retaining the smoky character during the smoking process of foods; a presentation of the development and characterization of a lab-scale smoke generator for smoking foods; and finally three chapters dealing with smoky alcoholic beverages, namely Bavarian wheat-beer and Scotch whiskies from the island of Islay, and how the associated odor-active compounds elicit the characteristic flavor, as well as a report on a novel method for quantifying their amounts.

Smoky beers and whiskies offer a transition to the final section of the book, which deals with other distilled spirits. Spirits are well known for their characteristic flavor subtleties and regional variations. The analysis of the flavor-active volatiles of distilled spirits can be challenging due to high levels of ethanol that can make volatile isolation difficult. The chapters in the spirits section of this book encompass reports on complex flavor chemistries of distilled spirits, which often show a high degree of flavor diversity that requires precise, quantitative analysis of volatiles. The spirits chapters include: a review of the diverse nature of spirits in terms of their production and flavor characteristics; a discourse summarizing traditional Chinese baijiu distilled spirit in terms of volatile composition; a report on sesame flavor in baijiu; an exploration of the aroma composition of barley-based Tibetan Qingke liquor in comparison to other baijiu spirits; a similar treatment of Wuliangye liquor; empirical data on the aroma composition of the Folium isatidis leaf, a raw material used for Chinese liquor; an exploration of how adding water to your spirit beverage impacts its flavor; a report on using the “sensomics” approach to unravel the relationship between chemical content and sensory impact in rum; and finally a report on the use of a stir-bar sorptive extraction (SBSE) in the analysis of volatile compounds in Tequila.

Overall, this book presents a snapshot of the latest research covering emerging challenges in chemistry in relation to sexual attraction, smoky flavors, and alcoholic spirits. We hope that researchers in the field will benefit from the range of studies presented in this book and their notable commonalities.

We are grateful to the authors for contributing their chapters and to the numerous reviewers who carefully read and commented on the chapters of this book to help improve their quality. We would like to express thanks for the wonderful help and support – and patience! – from the staff at the ACS Books Editorial Office, especially Chris Moffitt and Amanda Koenig.