Current Status and Future Perspectives in Flavor Research: Highlights

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Symposium Introduction

Current Status and Future Perspectives in Flavor Research: Highlights of the 11th Wartburg Symposium on Flavor Chemistry & Biology Thomas Hofmann, Dietmar Krautwurst, and Peter Schieberle J. Agric. Food Chem., Just Accepted Manuscript • DOI: 10.1021/acs.jafc.7b06144 • Publication Date (Web): 03 Jan 2018 Downloaded from http://pubs.acs.org on January 3, 2018

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Journal of Agricultural and Food Chemistry

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Current Status and Future Perspectives in Flavor Research: Highlights of

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the 11th Wartburg Symposium on Flavor Chemistry & Biology

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Thomas Hofmann1,2*, Dietmar Krautwurst2, and Peter Schieberle2,3

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Chair of Food Chemistry and Molecular and Sensory Science, Technische

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Universität München, Lise-Meitner-Str. 34, D-85354 Freising, Germany, and

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Leibniz-Institute for Food Systems Biology at the Technical University of Munich

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(formerly: Deutsche Forschungsanstalt für Lebensmittelchemie), Lise-Meitner-Str. 34,

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D-85354 Freising, Germany 3

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Lehrstuhl für Lebensmittelchemie, Technische Universität München, Lise-Meitner Strasse 34, D-85354 Freising

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*

To whom correspondence should be addressed

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PHONE

+49-8161/71-2902

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FAX

+49-8161/71-2949

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E-MAIL

[email protected]

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ABSTRACT

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The 11th Wartburg Symposium on Flavor Chemistry & Biology, held at the hotel “Auf

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der Wartburg” in Eisenach, Germany, from June 21 to 24 in 2016, offered a venue for

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global exchange on cutting-edge research in chemistry and biology of odor and taste.

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The focus areas were (1) Functional Flavor Genomics and Biotechnology, (2) Flavor

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Generation and Precursors, (3) New Approaches and Precursors, (4) New

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Approaches

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Relationships, (6) Food-Borne Bioactives and Chemosensory Health Prevention, and

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(7) Chemosensory Reception, Processing, and Perception. Selected from more than

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250 applicants, 160 distinguished scientists and rising stars from academia and

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industry from 24 countries participated in this multidisciplinary event. This special

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issue comprises a selection of 33 papers from oral presentations and poster

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contributions, and is prefaced by this introduction paper to carve out essential

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achievements in odor and taste chemistry and to share future research perspectives.

and

Technologies,

(5)

New

Molecules

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KEYWORDS

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Wartburg symposium, flavor, taste, aroma, chemoreceptors

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and

Structure/Activity


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History of the Wartburg Symposium. Scientific exchange on flavor research at the

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historical Wartburg Castle in Eisenach, Germany, dates back to 1978, when political

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conflicts between Eastern and Western Europe reached their maximum. At this time,

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Cornelius Weurman, a pioneer of flavor research who later organized the first

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Weurman Symposium in 1975, had the idea to bring together all existing European

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research groups. But he neglected that contacts between East and West European

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scientists were rather difficult at that time and were hindered by the Eastern political

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situation. As most Eastern European scientist did not have the chance to participate

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in meetings organized outside Eastern Europe, Martin Rothe, who introduced the

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consideration of odor thresholds in the evaluation of a compound’s odor contribution,1

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followed the idea to establish a separate Aroma Symposium in Eastern Europe. The

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Wartburg was selected for this symposium because of its historical background as

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well as the central geographic position in Germany. But the political problems could

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not be overcome. The organizers of the 1st Wartburg Aroma Symposium were clearly

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asked by the East German government, not only to select participants under

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scientific, but also political aspects. Considering this difficult situation, the organizers

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were proud about the active participation of eight well-known West European

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scientists, among them Werner Grosch, one of the inventors of the aroma extract

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dilution analysis (AEDA) and the odor activity value (OAV) concept,2 which was later

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further refined by Peter Schieberle,3,4 one of the organizers of the Wartburg

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symposium. In the past 40 years, the Wartburg Symposium has convened every

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three years and is today internationally respected as one of the most influential

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international symposia on flavor chemistry with firmly established bridges to biology

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and neurophysiology of smell and taste.

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Achievements in Flavor Research. Primarily driven by the introduction of

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gas chromatography in the nineteen sixties, the primary objective in the early days of ACS Paragon Plus Environment

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flavor research was to characterize as many volatiles in foods as possible. This led to

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the identification of about 8,000 volatiles and supported the prediction of a total of

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~10,000 volatiles to occur in foods.5,6 However, dose/activity considerations fed

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increasing doubts that the typical aroma of a given food is caused by a huge number

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of volatiles, and Martin Rothe, the founder of the Wartburg symposium, was one of

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them.1-3 This induced a paradigm shift in flavor research, fueled by the birth of GC-

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olfactometry (GC-O), enabling the localization of aroma-relevant odorants among the

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bulk of sensorially inactive volatiles in the chromatographic effluent by human

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“sniffing” detection.7-10 By repeated GC-O analysis of serially diluted aroma distillates,

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charm analysis10 or aroma extract dilution analysis (AEDA)2-4,10 even allowed the

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ranking of the odorants detected with respect to their sensory impact, and helped to

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focus the laborious identification experiments on the most intense food odorants. As

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the GC-O screening of key odorants is based on their threshold in air and not in the

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respective food matrix, researchers then started to study the contribution of individual

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odorants to a given food aroma on the basis of “odor activity values” (OAV) defined

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as the ratio of the concentration of an odorant in the food and its odor threshold in an

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appropriate matrix.1-4,12-14 This concept demonstrated that the rather unlimited

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variations in food flavors are due to a “combinatorial chemosensory code” (Figure

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1A), comprising a surprisingly small center group of 3-40 volatile key food odorants

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among the several ten thousands of non-odor active food constituents.

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In the early years of the new millennium, flavor chemistry was expanded by

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applying the principle of bioresponse-guided identification of odorants to non-volatile

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taste-active compounds. In particular, the application of the taste dilution analysis

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(TDA)15 and the comparative taste dilution analysis (cTDA)16 have led to the

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discovery of previously unknown key taste molecules and taste modulators in

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thermally processed foods like chicken broth,17 beef juice,18 hazelnuts,19 cooked ACS Paragon Plus Environment


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crustaceans,20 roasted coffee,21 fermented foods like Gouda and Parmesan

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cheese,22-25 red wine,26 beer and hops,27,28 black tea,29 fish sauce,30 balsamic

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vinegar,31 and yeast extracts,32 and plant-derived products like cocoa,33 Tasmanian

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pepper,34 carrots,35 and asparagus,36 respectively. Very recently, for the first time,

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odorants have been discovered to exhibit taste modulatory function, e.g. (R)-

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citronellal has been reported to attenuate caffeine bitterness by inhibiting the bitter

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receptors TAS2R43 and TAS2R46.37

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Counteracting analytical challenges in accurate quantitation of odorants and

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tastants, which are largely differing in concentration, volatility, and chemical stability,

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the so-called stable isotope dilution analysis (SIDA) was introduced in flavor

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research, using stable isotope (13C, 2H)-labeled twin molecules of the odorants and

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tastants as most suitable internal standards for GC-MS and LC-MS analysis.2-4,10,38-40

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Most impressively, minimal chemosensory recombinates of 3 to 40 key odorants and

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15-40 key tastants have been demonstrated to be truly necessary and sufficient for

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“synthesizing” the authentic percept of a specific food’s odor such as, e.g. black tea41

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and red wine (Figure 1B),39 although the overall flavor quality was not represented

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by any of the single ingredients alone.42 Therefore, the key mechanism by which the

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brain encodes perceptual representations of behaviorally relevant food items is

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through the synthesis of combinatorial chemosensory inputs into a unique perceptual

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experience (“flavor object”), rather than through individual molecules.42 In

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contradiction to traditional views, the sheer unlimited variations in food flavors is

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today accepted to be due to a “combinatorial chemosensory code” (Figure 1A)

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comprising a surprisingly small center group of 3-40 volatile key food odorants and

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10-40 non-volatile key food tastants among the several ten thousands of food

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constituents.31,39,42


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The hedonic differentiation and evaluation of these food flavor signatures is

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due to the high discriminatory power of the olfactory and gustatory system.42,43 A

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food’s chemical flavor profile is translated into specific receptor activity patterns

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elicited by the interaction of the mixture of chemosensory key molecules with their

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best cognate receptors out of the ~400 olfactory und ~30 taste receptors, among

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which sweet and umami tastes are mainly mediated by TAS1R receptor

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heterodimers44-46 while the perception of bitterness is mediated by 25 G-protein-

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coupled TAS2R receptors.47-49 Although these flavor objects enable us to make food

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choice decisions, surprisingly little is known about the human receptor activation

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patterns for single food odorants and tastants, and nothing is known about receptor

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codes for chemosensory mixtures as recently exemplified for the odorant receptor

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code of cultured butter (Figure 1C).50 Moreover, knowledge is rather limited on the

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complementation as well as co-activation of bitter taste receptors by the various

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bitter-tasting molecules present in foods and beverages such as, e.g. beer,51

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cheese,52 stevia extract,53 carrots, and coffee (unpublished data), respectively

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(Figure 2). In consequence, the minimal chemosensory recombinates, rather than

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individual stimuli, seem to be most promising “molecular probes” for future research

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to decode the mechanisms triggering food preference and aversive behaviors.

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Scientific Challenges and Future Perspectives. Today’s challenges in

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flavour research are multifold: To overcome flavor defects in healthy food products,

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reduced in salt, sugar, monosodium glutamate (MSG), and fat, respectively, the food

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and nutrition sector relies on new solutions and technologies capable of fine-tuning

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aroma deviations as well as the use of natural and/or biosynthetic, high-potency taste

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modulation systems for the delivery of truly authentic flavor signatures.

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Independent from their sensory quality, most food-borne key odorants/tastants

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are generated from precursors in the raw materials upon processing and/or ACS Paragon Plus Environment


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fermentation of foods and their generation is strongly dependent on the processing

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conditions. Representing the molecular blueprint of our food’s chemosensory

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signature, the population of key flavor compounds, coined “sensometabolome”,24

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may be used as a molecular target for visualizing the changes in odor and taste

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profiles from the raw materials through the various manufacturing process

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intermediates all the way up-stream to the consumer’s plate by high-precision and

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high-throughput mass spectrometric profiling. This will open new avenues for a more

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scientifically directed taste improvement of foods by tailoring processing parameters

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(“molecular food engineering”); for example, targeted food-borne generation of high-

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potency salt, sweet, umami, or mouthfullness (kokumi) enhancers will help to

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overcome taste defects in salt, sugar, and MSG-reduced food products without

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artificial ingredients. Also the efficient control of bitter off-tastes of food products and

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phytochemical supplemented products might be possible by suppressing bitter taste

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perception by means of controlled generation of food-borne bitter inhibitors.

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Molecular knowledge of the odor code of crops and vegetables holds promise

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for major improvements in future breeding strategies, which in the past have been

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targeted primarily towards field performance, yield, and storage characteristics, while

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ignoring quality traits such as aroma and taste. The analytical assessment of the key

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odorants and tastants would greatly facilitate the accurate evaluation of a large

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number of progeny, thus moving the selection of flavor earlier in the selection

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sequence and increasing the chance of finding truly superior new cultivars for a wide

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cross-section of food crops. Therefore, advances in flavor chemistry and biology hold

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promise to become truly a game-changer helping to transform the incremental

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product improvement approaches of our today’s industry into a consumer-centric re-

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engineering strategy, more effectively targeting food development to consumers’

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preference, acceptance, and needs. ACS Paragon Plus Environment

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To achieve all this, we need modern analytical technologies to speed up the

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discovery of unknown chemosensory active molecules in nature’s unlimited box of

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molecules and to understand their physico-chemical interactions with food matrix

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constituents on a molecular level. We need to learn how to optimize the gene

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computer of plants and to utilize the biosynthetic power of plants and microorganisms

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to produce target flavor molecules in high yields and also high enantioselectivity. In

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addition, we should use our knowledge on the combinatorial chemosensory codes for

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a targeted navigation of breeding and post-harvest processing parameters to support

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plant breeders in the development of premium tasty plant materials.

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New research is required to increase our knowledge on the molecular

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alterations of salivary composition upon stimulation with odorants and tastants,54,55 as

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well as the receptor proteins involved in sensing of odorants, tastants, and additional

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stimuli such as fat. We need to understand how our foods’ combinatorial

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chemosensory codes are translated into food-specific chemosensory receptor

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activation patterns and how this can be modulated to develop premium tasty and

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healthy food products with reduced levels of, e.g., salt, sugar, and fat.

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More fundamental knowledge is urgently needed from the secretion of

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neurotransmitters to the induction of neural activity that is conveyed to the cerebral

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cortex to represent the distinct odor and taste qualities. As food preferences and

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aversions have been reported to develop across life stages and individual differences

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in chemosensory receptor genotypes to affect flavor experience and food selection,56-

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genotypic differences with respect to sensory preference for and aversion against

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food flavors. Intriguingly, the conditioned aversion for odorants in mice has been

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shown to be maintained over two generations60, indicating epigenetic modification to

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play a key role not only in mono-allelic odorant receptor gene activation,61 but also in

we need to entangle individual age-dependent chemosensory pheno- and



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sensory programming and development of nutritional preferences/aversions across

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life stages.62 Last but not least, we have to furtherance our knowledge on the

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biotransformation of odorants and tastants in the nasal and oral cavity, but also on

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the biological response induced upon their ingestion.

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Without any doubt, advancement in these fields will crucially depend on how

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consequently scientists will dare to leave the trampling paths of their own disciplines,

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and will learn to live up their science in a interdisciplinary environment, striving to

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generate synergies by bundling the different expertise and technology know-how of

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research in food and natural product chemistry, psychophysics and sensory science,

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nutrition and health sciences, biotechnology, plant biology and genetics, human

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biology, genetics and neurophysiology, respectively. Exactly this profile rounds out

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the Wartburg Symposium’s characteristic signature as a fruitful retreat to discuss

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emerging cross-disciplinary challenges in a relaxing atmosphere.

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The 11th Wartburg Symposium on Flavor Chemistry & Biology. To tackle

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these truly cross-disciplinary research challenges, top-tier flavor chemistry and

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biology once more returned back to the “Hotel on the Wartburg” in Eisenach,

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Germany. Between June 21 and 24 in 2016, this symposium offered a venue for

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global exchanges and knowledge calibration of the state of the art research in flavor

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chemistry and biology and for the presentation and discussion of latest advances and

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future research opportunities. Compared to its infant days, flavor research has

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embarked on a journey beyond its traditional core disciplines in chemistry and

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sensory analysis, and has begun to valorize the sweet spots emerging at the

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intersection with biotechnology, human biology, and neurophysiology.

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Selected from more than 250 applicants, 160 distinguished scientists and

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rising stars from academia and industry from 24 countries and 4 continents

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participated in this highly multidisciplinary event on the historic castle (Figure 3). ACS Paragon Plus Environment

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Experts from analytical and natural product chemistry, psychophysics and sensory

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science, nutrition and health sciences, biotechnology, plant biology and genetics,

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human biology and neurophysiology, and imaging technologies shared expertise and

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new insights, calibrated their knowledge, and exchanged on future perspectives.

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This special issue presents a selection of 33 papers from oral and flash poster

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presentations and poster contributions shown in the thematic symposium sessions

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(1) Functional Flavor Genomics and Biotechnology, (2) Flavor Generation and

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Precursors, (3) New Approaches and Precursors, (4) New Approaches and

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Technologies, (5) New Molecules and Structure/Activity Relationships, (6) Food-Born

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Bioactives and Chemosensory Health Prevention, and (7) Chemosensory Reception,

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Processing and Perception, and demonstrates the depth and broad scope of the

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science presented at the Wartburg symposium. The former idea of bringing together

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people from Eastern and Western Europe was replaced in favour of building

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multinational bridges between different scientific disciplines – and this will also shape

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the unique signature of future Wartburg Symposia.

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The 12th Wartburg Symposium in 2019. The next Wartburg Symposium on

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Flavor Chemistry & Biology will be held from May 21 to May 24, 2019 at the historic

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Wartburg Castle. If you want to see the latest developments at the intersection of

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chemistry and biology of flavors, make your plans to be there.

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ACKNOWLEDGEMENT

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The organizers are grateful to all the sponsors for their generous support, which

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helped to offset the travel expenses of invited speakers and other costs to run the

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symposium: the Gold sponsors, namely, PepsiCo, Mars, Nestle, Altria, General Mills, ACS Paragon Plus Environment


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DSM, and Philip Morris; the Silver sponsors, namely Döhler, Hasegawa, Givaudan,

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Lucta, Takasago, Symrise, Gerstel, and Mondelez; and the Bronze sponsors, namely

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Ajinomoto, Aromalab, Wakunaga, Bell Flavors, Flavologic, and the American

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Chemical Society (ACS). In addition, we thank the German Research Center for

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Food Chemistry, and the Technical University of Munich for supporting the

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organization of the symposium with staff and expertise, in particular, Corinna Dawid

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for planning and organization of the symposium and Andreas Dunkel for the technical

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support. We also would like to thank the Wartburg Stiftung and, in particular, Andreas

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Volkert, for making it again possible to use the stimulating historic place with the

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knights hall for that symposium, and the hotel staff for creating a friendly and warm

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atmosphere in the hotel “Auf der Wartburg”.

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LITERATURE CITED

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using threshold concentrations (in German). Z. Lebensm.-Unters. Forsch. 1975,

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aroma models and omission. Chem. Senses 2001, 26, 533-545.

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Grosch, W. Evaluation of the key odorants of foods by dilution experiments,

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Schieberle, P. New developments on methods for analysis of volatile flavor

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compounds and their precursors. In: Characterization of food-emerging

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methods (A. G. Gaonkar, Ed.), 1995, Elsevier, Amsterdam, 1995, pp. 403-433.

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Hofmann, T.; Schieberle, P. Elucidation of the chemosensory code of foods by means of a sensomics approach. Flavour Science - Proceedings of the XIV


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Weurman Flavour Research Symposium (Taylor A.J., Mottram

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eds),

VCF Volatile Compounds in FOOD, database version 14.1 (Eds.: L. M. Nijssen, C. A. Ingen-Visscher, J. J. H. van Donders), TNO Triskelion, Zeist, 2013.

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Frank, D.; Ball, A.; Hughes, J.; Krishnamurthy, R.; Piyasiri, U.; Stark, J.;

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Watkins, P.; Warner, P. Sensory and flavor chemistry characteristics of

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Australian beef: influence of intramuscular fat, feed, and breed. J. Agric. Food

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strawberry juice by quantitative measurements and sensory studies on model

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11. Acree, E.; Barnard, J.; Cunningham, D.G. A procedure for the sensory analysis of gas chromatographic effluents. Food. Chem. 1984, 14, 273-286.

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12. Buttery, R.G. Quantitative and sensory aspects of flavior of tomato and other

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vegetables and fruits. In: Flavor Science. Sensible Principles and Techniques

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(Eds.: T. E. Acree, R. Teranishi), American Chemical Society, Washington DC,

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1993, 259-286.

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13. Wagner, J.; Granvogl, M.; Schieberle, O. Characterization of the key aroma

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compounds in raw licorice (Glycyrrhiza glabra L.) by means of molecular

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sensory science. J. Agric. Food Chem., 2016, 64, 8388–8396. ACS Paragon Plus Environment


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14. Xiao, Z.; Wu, Q.; Niu, Y.; Wu, M.; Zhu, J.; Zhou, X.; Chen, X.; Wang, H.; Li, J.;

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Kong, J. Characterization of the key aroma compounds in five varieties of

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mandarins by gas chromatography-olfactometry, odor activity values, aroma

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recombination, and omission analysis. J. Agric. Food Chem. 2017, 65, 8392-

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8401.

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15. Frank O., Ottinger H., Hofmann T. (2001) Characterization of an Intense Bitter-

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tasting 1H,4H-Quinolizinium-7-olate by Application of the Taste Dilution

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Analysis, A Novel Bioassay for the Screening and Identification of Taste-active

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Compounds in Foods. J. Agric. Food Chem., 49, 231-238.

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16. Ottinger H., Soldo T., Hofmann T.

(2003) Discovery and Structure

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Determination of a Novel Maillard-Derived Sweetness Enhancer by Application

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of the Comparative Taste Dilution Analysis (cTDA). J. Agric Food Chem., 51,

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1035-1041.

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17. Dunkel, A.; Hofmann, T., Sensory-directed identification of beta-alanyl

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dipeptides as contributors to the thick-sour and white-meaty orosensation

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induced by chicken broth. J. Agric. Food Chem. 2009, 57, 9867-77.

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18. Ottinger, H.; Hofmann, T., Identification of the taste enhancer alapyridaine in

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beef broth and evaluation of its sensory impact by taste reconstitution

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experiments. J. Agric. Food Chem. 2003, 51, 6791-6796.

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19. Singldinger, B.; Dunkel, A.; Hofmann, T. The cyclic diarylheptanoid asadanin as

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the main contributor to the bitter off-taste in hazelnuts (Corylus avellana L.). J.

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Agric. Food Chem. 2017, 65, 1677-1683.

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20. Meyer, S.; Dunkel, A.; Hofmann, T., Sensomics-Assisted Elucidation of the

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Tastant Code of Cooked Crustaceans and Taste Reconstruction Experiments.

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J. Agric. Food Chem. 2016, 64, 1164-75.


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21. Frank, O.; Zehentbauer, G.; Hofmann, T. Bioresponse-guided decomposition of

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roast coffee beverage and identification of key bitter taste compounds, Eur.

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Food Res. Technol. 2005, 222, 492-508.

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22. Toelstede, S.; Dunkel, A.; Hofmann, T., A Series of Kokumi Peptides Impart the

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Long-Lasting Mouthfulness of Matured Gouda Cheese. J. Agric. Food Chem.

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2009, 57, 1440-1448.

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23. Toelstede, S.; Hofmann, T., Quantitative studies and taste re-engineering

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experiments toward the decoding of the nonvolatile sensometabolome of Gouda

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cheese. J. Agric. Food Chem. 2008, 56, 5299-5307.

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24. Toelstede, S.; Hofmann, T., Sensomics mapping and identification of the key

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bitter metabolites in Gouda cheese. J. Agric. Food Chem. 2008, 56, 2795-2804.

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25. Hillmann, H.; Hofmann, T. Quantitation of key tastants and re-engineering the

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taste of Parmesan cheese. J. Agric. Food Chem. 2016, 64, 1794-805. 26. Hufnagel, J. C.; Hofmann, T., Quantitative reconstruction of the nonvolatile sensometabolome of a red wine. J. Agric. Food Chem. 2008, 56, 9190-9199.

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27. Intelmann, D.; Haseleu, G.; Dunkel, A.; Lagemann, A.; Stephan, A.; Hofmann,

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T. Comprehensive sensomics analysis of hop-derived bitter compounds during

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storage of beer. J. Agric. Food Chem. 2011, 59, 1939-1953.

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28. Dresel, M.; Vogt, Ch.; Dunkel, A.; Hofmann, T. The bitter chemodiversity of hops (Humulus lupulus L.). J. Agric. Food Chem., 2016, 64, 7789–7799.

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29. Scharbert, S.; Holzmann, N.; Hofmann, T. Identification of the astringent taste

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compounds in black tea infusions by combining instrumental analysis and

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human bioresponse, J. Agric. Food Chem. 2004, 52, 3498–3508.

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30. Schindler, A.; Dunkel, A.; Stähler. F.; Backes, M.; Meyerhof, W.; Hofmann, T.

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Discovery of salt taste enhancing arginyl dipeptides in protein digests and



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fermented fish sauces by means of a sensomics approach. J. Agric Food

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Chem. 2011, 59, 12578-12588.

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31. Hillmann, H.; Mattes, J.; Brockhoff, B.; Dunkel, A.; Meyerhof, W.; Hofmann, T.

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Sensomics analysis of taste compounds in balsamic vinegar and discovery of 5-

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acetoxymethyl-2-furaldehyde as a novel sweet taste modulator. J. Agric. Food

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Chem. 2012, 60, 9974–9990.

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32. Festring, D.; Hofmann, T., Discovery of N(2)-(1-carboxyethyl)guanosine 5'-

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monophosphate as an umami-enhancing maillard-modified nucleotide in yeast

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extracts. J. Agric. Food Chem. 2010, 58, 10614-22.

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33. Stark, T.; Hofmann, T. Isolation, structure determination, synthesis, and sensory

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activity of N-phenylpropenoyl-L-amino acids from cocoa (Theobroma cacao), J.

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Agric. Food Chem. 2005, 53, 5419–5428.

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34. Mathie, K.; Lainer, J.; Spreng, S.; Dawid, C.; Andersson, D.A.; Bevan, S.;

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Hofmann, T. Structure–pungency relationships and TRP channel activation of

363

drimane sesquiterpenes in Tasmanian pepper (Tasmannia lanceolata). J. Agric.

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Food Chem., 2017, 65, 5700–5712.

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35. Czepa, A.; Hofmann, T. Structural and sensory characterization of compounds

366

contributing to the bitter off-taste of carrots (Daucus carota L.) and carrot puree,

367

J. Agric. Food Chem. 2003, 51, 3865–3873.#

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36. Dawid, C.; Hofmann, T. Structural and sensory characterization of bitter tasting

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steroidal saponins from Asparagus apears (Asparagus officinalis L.), J. Agric.

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Food Chem. 2012, 60, 11889–11900.

371

37. Suess, B.; Brockhoff, A.; Meyerhof, W.; Hofmann, T. The odorant (R)-citronellal

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attenuates caffeine bitterness by inhibiting the bitter receptors TAS2R43 and

373

TAS2R46. J. Agric. Food Chem. 2017, DOI: 10.1021/acs.jafc.6b03554


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38. Kiefl, J.; Pollner, G.; Schieberle, P. Sensomics analysis of key hazelnut

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odorants (Corylus avellana L. 'Tonda Gentile') using comprehensive two-

376

dimensional gas chromatography in combination with time-of-flight mass

377

spectrometry (GC×GC-TOF-MS). J. Agric. Food Chem. 2013, 61, 5226-5235.

378

39. Frank, S.; Wollmann, N.; Schieberle, P.; Hofmann, T. Reconstitution of the

379

flavor signature of Dornfelder red wine on the basis of the natural

380

concentrations of its key aroma and taste Compounds. J. Agric. Food Chem.

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2011, 59, 8866-8874.

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40. Stark T., Justus H., Hofmann T. Quantitative analysis of N-phenylpropenoyl-L-

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amino acids in roasted coffee and cocoa powder by means of a stable isotope

384

dilution assay. J. Agric. Food Chem. 2006, 54, 2859-2867.

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41. Schieberle P., Hofmann T. In: Food Flavors - Chemical, Sensory and

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Technological Properties (H. Jelen, ed.); CRC Press, Taylor and Francis Group,

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388

42. Dunkel, A.; Steinhaus, M.; Kotthoff, M.; Nowak, B.; Krautwurst, D.; Schieberle,

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P.; Hofmann, T. Nature’s chemical signatures in human olfaction: a foodborne

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perspective for future biotechnology. Angew. Chem. Int. Ed. 2014, 53, 7124-714

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43. Olender, T.; Waszak, S.; Viavant, M.; Khen, M.; Ben-Asher, E.; Reyes, A.;

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olfaction as a model BMC Genomics 2012, 13, 414.

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44. Li, X.; Staszewski, L.; Xu, H.; Durick, K.; Zoller, M.; Adler, E. Human receptors

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for sweet and umami taste. Proc. Natl. Acad. Sci USA 2002, 99, 4692-4696.

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45. Behrens, M.; Meyerhof, W.; Hellfritsch, C.; Hofmann, T. Sweet and umami

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taste: natural products, their chemosensory targets, and beyond. Angew. Chem.

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46. Nelson, G.; Chandrashekar, J.; Hoon, M.A.; Feng, L.; Zhao, G.; Ryba, N.J.P.; Zuker, C.S. An amino-acid taste receptor. Nature 2002, 416, 199-202. 47. Adler, E.; Hoon, M.A.; Mueller, K.L.; Chandrashekar, J.; Ryba, N.J.; Zuker, C.S. A novel family of mammalian taste receptors. Cell 2000, 100, 693-702.

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48. Chandrashekar, J.; Mueller, K.L.; Hoon, M.A.; Adler, E.; Feng, L.; Guo, W.;

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Zuker, C.S.; Ryba, N.J. T2Rs function a bitter taste receptors. Cell 2000, 100,

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703-711.

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49. Matsunami, H.; Montmayeur, J.P.; Buck, L.B. A family of candidate taste receptors in human and mouse. Nature 2000, 404, 601-604.

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50. Geithe, C.; Andersen, G.; Malki, A., Krautwurst, D. A butter aroma recombinate

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activates human class-I odorant receptors. J. Agric. Food Chem. 2015, 63,

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9410-9420.

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51. Intelmann, D.; Batram, C.; Kuhn, Ch.; Haseleu, G.; Meyerhof, M.; Hofmann, T.

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Three TAS2R bitter taste receptors mediate the psychophysical responses to

413

bitter compounds of hops (Humulus lupulus L.) and beer, Chem. Percept. 2009,

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2, 118-132.

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52. Kohl, S.; Behrens, M.; Dunkel, A.; Hofmann, T.; Meyerhof, W. Amino acids and

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peptides activate at least five members of the human bitter taste receptor

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family. J. Agric. Food Chem. 2013, 61, 53-60.

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53. Hellfritsch, C.; Brockhoff, A.; Staehler , F.; Meyerhof, W.; Hofmann, T. Human

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psychometric and taste receptor responses to steviol glycosides. J. Agric. Food

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Chem. 2012, 60, 6782-6793.

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54. Delius, J.; Médard, G.; Kuster, B.; Hofmann, T. Effect of astringent stimuli on

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salivary

protein

interactions

elucidated

by

423

approaches. J. Agric. Food Chem. 2017, 65, 2147-2154.


complementary

proteomics

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55. Stolle, T.; Grondinger, F.; Dunkel, A.; Meng, C.; Médard, G.; Kuster, B.;

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Hofmann, T. Salivary proteome patterns affecting human salt taste sensitivity. J.

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56. Doty, R.L.; Kamath, V. The influences of age on olfaction: a review. Front Psychol. 2014, 5, 20. eCollection 2014 57. Mennella, J.A.; Finkbeiner, S.; Reed, D.R. The proof is in the pudding: children prefer lower fat but higher sugar than do mothers. Int. J. Obes. 2012, 36, 1285.

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genotype-phenotype relationship for the bitter receptor TAS2R38. BMC Genet.

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2010, 11, 60

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59. Jaeger, S.R.; McRae, J.F.; Bava, C.M.; Beresford, M.K.; Hunter, D.; Jia, Y.;

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60. Dias, B.G.; Ressler, K.J. Parental olfactory experience influences behavior and

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61. Reinsborough, C.; Chess, A. An epigenetic trap involved in olfactory receptor

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gene choice. Dev. Cell. 2013, 26, 120-121. 62. Langley-Evans, S.C. Nutrition in early life and the programming of adult disease: a review. J. Hum. Nutr. Diet. 2015, 28, 1-14.

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446

Figure Legend

447 448

Figure 1.

(A) Heatmap displaying odor activity values (OAVs) of the 226 key food

449

odorants (KFOs) characterized in 227 food samples.42 (B) Sensory

450

profile of an authentic red wine vs. a minimal biomimetic flavor

451

recombinate comprising 28 key food odorants and 35 key food

452

tastants.39 (C) EC50-based odorant receptor activation barcodes elicited

453

by a minimal recombinant exemplified with a 3-compound recombinate

454

of cultured butter aroma.50

455

Figure 2.

tastants in beer, coffee, carrots, cheese, and Stevia.

456 457

Bitter taste receptor complementation and co-activation by bitter

Figure 3.

The global science community met at the hotel “Auf der Wartburg” in

458

Eisenach, Germany, from June 21 to 24 in 2016, to participate in the

459

11th Wartburg Symposium on Flavor Chemistry & Biology.

460 461

462

463


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Figure 1 (Hofmann et al.)

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466


467 468

469 470 471 472 473


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Current Status and Future Perspectives in Flavor Research: Highlights

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