Occurrence of 2-Acetyl-1-pyrroline and Its Nonvolatile Precursors in Celtuce (Lactuca sativa L. var. augustana).

Lactuca sativa L. var. augustana has a basmati rice-like odor with a green note in the background. This typical odor is due to the release of 2-acetyl-1-pyrroline (2-AP) after heating, which is confirmed by volatile analysis. Recent metabolomic and genomic studies of different rice varieties highlighted that the presence of 2-AP was linked to the accumulation of γ-aminobutyraldehyde; genome-wide association studies also indicated that acyltransferases were involved. These results prompted us to analyze nonvolatile compound precursors in L. sativa L. var. augustana (celtuce) to search for compound derivatives with a 4,5-dioxohexan alkyl amine-like structure. Hypothetical synthetic compounds were prepared from a reductive amination between 4,5-dioxohexanal and glycine, alanine, aspartic acid, and glutamic acid to give 2-(2-acetylpyrrolidin-1-yl) alkanoic acid. We proved that 2-(2-acetylpyrrolidin-1-yl) propionic acid is present in L. sativa, which, when thermally treated, released 2-AP. Other 2-AP precursors occurring in this plant are discussed.

Simulating latrine conditions to assess perfume performance against malodour.

To evaluate perfume performance in toilets, we built model toilets in which critical factors such as background malodour, climate, and airflow were controlled. The models were equipped with an odour generator that injected hydrogen sulfide, methyl mercaptan, butyric acid, para-cresol, and indole, allowing us to accurately and reliably reconstitute toilet malodour headspace. The malodorant concentrations matched the quantitative headspace analysis performed in African and Indian toilets. The toilet malodour headspace performance was validated by chemical and sensory analysis. Olfactory stimuli were presented to participants in different simulated climates to assess the effect of climate on the perception of odours. The sensory data show that increasing temperature and humidity decreased the intensity ratings of odours without altering their quality. Perfume can be delivered in these toilets by forced evaporation to control the headspace concentration, or by delivery systems such as cellulosic pads, liquids, and powders. Our experimental set-up allowed us to establish dose-response curves to assess the performance of a perfume in reducing toilet malodour and increasing perceived pleasantness.

Behavioral response of the malaria mosquito, Anopheles gambiae, to human sweat inoculated with axilla bacteria and to volatiles composing human axillary odor.

The responses of Anopheles gambiae Giles sensu stricto (Diptera: Culicidae) to odors from male and female axillary sweat incubated with human axilla bacteria were recorded in a dual-choice olfactometer. Staphylococcus epidermidis was selected for its low odor-producing pattern, Corynebacterium jeikeium for its strong Nα-acylglutamine aminoacylase activity liberating carboxylic acids including (R)/(S)-3-hydroxy-3-methylhexanoic acid (HMHA) and Staphylococcus haemolyticus for its capacity to liberate sulfur-containing compounds including (R/S)-3-methyl-3-sulfanylhexan-1-ol (MSH). Anopheles gambiae behavioral responses were evaluated under (i) its responsiveness to take off and undertake sustained upwind flight and (ii) its discriminating capacity between the two olfactometer arms bearing a test odor in either one or both arms. Experiments were conducted in the presence of carbon dioxide pulses as a behavioral sensitizer. Anopheles gambiae clearly discriminated for the olfactometer arm conveying odor generated by incubating any of the three bacteria species with either male or female sweat. Whereas An. gambiae did not discriminate between male and female sterile sweat samples in the olfactometer, the mosquito consistently showed a preference for male sweat over female sweat incubated with the same bacterium, independent of the species used as inoculum. Sweat incubated with C. jeikeium rendered mosquitoes particularly responsive and this substrate elicited the strongest preference for male over female sweat. Tested on their own, neither HMHA nor MSH elicited a clear discriminating response but did affect mosquito responsiveness. These findings serve as a basis for further research on the odor-mediated anthropophilic host-seeking behavior of An. gambiae.

Identification of Hydrogen Disulfanes and Hydrogen Trisulfanes in H2S Bottle, in Flint, and in Dry Mineral White Wine.

Through the accidental contamination of a gas cylinder of H2S, the importance of polysulfanes for flint, gun powder, and match odors was discovered. The hydrogen disulfane was prepared from disulfanediylbis[methyl(diphenyl)silane], and its odor descriptor was evaluated in the gas phase from a gas chromatograph coupled to an olfaction port. The occurrence of this compound in flint and pebbles was confirmed by analyses after derivatization with pentafluorobromobenzene. The occurrence of this sulfane was also confirmed in two dry white Swiss Chasselas wines, sorted by a large-scale sensory analysis from 80 bottles and evaluated by 62 wine professionals. The occurrence of disulfane was confirmed for the two wines described as the most mineral. Polysulfane comprises a class of compounds contributing to the flint odor and that may contribute to the wine mineral odor descriptor. Due to the high volatility and instability pure HSSH was not isolated but kept in solution and its odor profile was described by gas chromatography coupled to an olfaction port as flint, matches, and fireworks with a higher odor intensity compared to H2S.

Quantitative headspace analysis of selected odorants from latrines in Africa and India.

This analytical investigation focuses on the quantification of odorant molecules in the headspace of latrines. Hydrogen sulfide and methyl mercaptan were derivatized under a more stable N-ethyl maleimide conjugate. Since the amount of odorant molecules is very low in the gas phase, we developed a method that had two steps of concentration. The first step consisted of the accumulation of volatiles in buffered water by bubbling 350 L of air in a bottle. The second step consisted of loading the water on a 1 g solid-phase extraction cartridge, shipping it to our laboratories, and desorbing with Et2O, which achieved a total concentration factor of 3.5 × 10(6). The acidification of the water phase gave us access to the acids, and an additional bottle containing an acidic ion-exchange resin gave us access to trimethyl amine. The limits of quantification in the gas phase were 8.7 × 10(-4) µg/L air for hydrogen sulfide, 1 × 10(-4) µg/L air for methyl mercaptan, 1 × 10(-3) µg/L air for butyric acid, 1 × 10(-4) µg/L air for p-cresol, 1 × 10(-5) µg/L air for indole, and 1 × 10(-5) µg/L air for skatole. The system was calibrated by using olfactometers, which can deliver a precisely known quantity of volatiles into the air. We were able to quantify all compounds near their odor detection thresholds (ODTs). All ODTs were measured in our laboratory with the same olfactometry method. This allowed accurate and comparable ODT values for malodorant compounds from toilets.

Mapping axillary microbiota responsible for body odours using a culture-independent approach.

BACKGROUND: Human axillary odour is commonly attributed to the bacterial degradation of precursors in sweat secretions. To assess the role of bacterial communities in the formation of body odours, we used a culture-independent approach to study axillary skin microbiota and correlated these data with olfactory analysis. RESULTS: Twenty-four Caucasian male and female volunteers and four assessors showed that the underarms of non-antiperspirant (non-AP) users have significantly higher global sweat odour intensities and harboured on average about 50 times more bacteria than those of AP users. Global sweat odour and odour descriptors sulfury-cat urine and acid-spicy generally increased from the morning to the afternoon sessions. Among non-AP users, male underarm odours were judged higher in intensity with higher fatty and acid-spicy odours and higher bacterial loads. Although the content of odour precursors in underarm secretions varied widely among individuals, males had a higher acid: sulfur precursor ratio than females did. No direct correlations were found between measured precursor concentration and sweat odours. High-throughput sequencing targeting the 16S rRNA genes of underarm bacteria collected from 11 non-AP users (six females and five males) confirmed the strong dominance of the phyla Firmicutes and Actinobacteria, with 96% of sequences assigned to the genera Staphylococcus, Corynebacterium and Propionibacterium. The proportion of several bacterial taxa showed significant variation between males and females. The genera Anaerococcus and Peptoniphilus and the operational taxonomic units (OTUs) from Staphylococcus haemolyticus and the genus Corynebacterium were more represented in males than in females. The genera Corynebacterium and Propionibacterium were correlated and anti-correlated, respectively, with body odours. Within the genus Staphylococcus, different OTUs were either positively or negatively correlated with axillary odour. The relative abundance of five OTUs (three assigned to S. hominis and one each to Corynebacterium tuberculostearicum and Anaerococcus) were positively correlated with at least one underarm olfactory descriptor. CONCLUSIONS: Positive and negative correlations between bacterial taxa found at the phylum, genus and OTU levels suggest the existence of mutualism and competition among skin bacteria. Such interactions, and the types and quantities of underarm bacteria, affect the formation of body odours. These findings open the possibility of developing new solutions for odour control.

5α-Androst-16-en-3α-ol ß-D-glucuronide, precursor of 5α-androst-16-en-3α-ol in human sweat.

5α-Androst-16-en-3α-ol (α-androstenol) is an important contributor to human axilla sweat odor. It is assumed that α-andostenol is excreted from the apocrine glands via a H2 O-soluble conjugate, and this precursor was formally characterized in this study for the first time in human sweat. The possible H2 O-soluble precursors, sulfate and glucuronide derivatives, were synthesized as analytical standards, i.e., α-androstenol, ß-androstenol sulfates, 5α-androsta-5,16-dien-3ß-ol (ß-androstadienol) sulfate, α-androstenol ß-glucuronide, α-androstenol α-glucuronide, ß-androstadienol ß-glucuronide, and α-androstenol ß-glucuronide furanose. The occurrence of α-androstenol ß-glucuronide was established by ultra performance liquid chromatography (UPLC)/MS (heated electrospray ionization (HESI)) in negative-ion mode in pooled human sweat, containing eccrine and apocrine secretions and collected from 25 female and 24 male underarms. Its concentration was of 79 ng/ml in female secretions and 241 ng/ml in male secretions. The release of α-androstenol was observed after incubation of the sterile human sweat or α-androstenol ß-glucuronide with a commercial glucuronidase enzyme, the urine-isolated bacteria Streptococcus agalactiae, and the skin bacteria Staphylococcus warneri DSM 20316, Staphylococcus haemolyticus DSM 20263, and Propionibacterium acnes ATCC 6919, reported to have ß-glucuronidase activities. We demonstrated that if α- and ß-androstenols and androstadienol sulfates were present in human sweat, their concentrations would be too low to be considered as potential precursors of malodors; therefore, the H2 O-soluble precursor of α-androstenol in apocrine secretion should be a ß-glucuronide.

Qualitative and quantitative analysis of volatile constituents from latrines.

More than 2.5 billion people defecate in the open. The increased commitment of private and public organizations to improving this situation is driving the research and development of new technologies for toilets and latrines. Although key technical aspects are considered by researchers when designing new technologies for developing countries, the basic aspect of offending malodors from human waste is often neglected. With the objective of contributing to technical solutions that are acceptable to global consumers, we investigated the chemical composition of latrine malodors sampled in Africa and India. Field latrines in four countries were evaluated olfactively and the odors qualitatively and quantitatively characterized with three analytical techniques. Sulfur compounds including H2S, methyl mercaptan, and dimethyl-mono-(di;tri) sulfide are important in sewage-like odors of pit latrines under anaerobic conditions. Under aerobic conditions, in Nairobi for example, paracresol and indole reached concentrations of 89 and 65 µg/g, respectively, which, along with short chain fatty acids such as butyric acid (13 mg/g) explained the strong rancid, manure and farm yard odor. This work represents the first qualitative and quantitative study of volatile compounds sampled from seven pit latrines in a variety of geographic, technical, and economic contexts in addition to three single stools from India and a pit latrine model system.

Development of an analytical approach for identification and quantification of 5-α-androst-16-en-3-one in human milk.

A method was developed for the quantification of 5-α-androst-16-en-3-one in human breast milk based on application of a stable isotope dilution assay using 5α-androst-16-en-3-one-6, 6-d(2). The procedure includes extraction of the human milk by hexane with subsequent clean-up of the obtained extract by gel permeation and silica gel column chromatography. The extracted samples were analyzed by gas chromatography-mass spectrometry. Using this method 5-α-androst-16-en-3-one could be identified and for the first time quantified in a concentration range of 26-155 ng/kg in human milk.

Volatile composition of oyster leaf (Mertensia maritima (L.) Gray).

Oyster leaf (Mertensia maritima), also called vegetarian oyster, has a surprising oyster-like aroma. Its volatile composition was investigated here for the first time. In total, 109 compounds were identified by gas chromatography-mass spectrometry (GC-MS) and quantified by GC-FID. The use of GC-olfactometry on both polar and nonpolar columns allowed the detection of the molecules having an oyster-like, marine odor. Four compounds were identified and confirmed by synthesis: (Z)-3-nonenal, (Z)-1,5-octadien-3-ol, (Z,Z)-3,6-nonadienal, and (Z)-1,5-octadien-3-one. After evaluation of freshly prepared reference samples, these compounds were confirmed to be reminiscent of the oyster-like marine notes perceived in the tasting of cut leaves.

Four windows on modern science in flavor and fragrance chemistry at Firmenich.

Four young scientists, recently hired by Firmenich, presented lectures at the University of Geneva. The objective was to stimulate young students to choose sciences. The challenges in the discovery, synthesis, or extraction of new molecules were presented, as well as the structure-activity relationships of human odorant receptors.

Nonvolatile S-alk(en)ylthio-L-cysteine derivatives in fresh onion (Allium cepa L. cultivar).

The L-cysteine derivatives (R)-2-amino-3-(methyldisulfanyl)propanoic acid (S-methylthio-L-cysteine), (R)-2-amino-3-(propyldisulfanyl)propanoic acid (S-propylthio-L-cysteine), (R)-2-amino-3-(1-propenyldisulfanyl)propanoic acid (S-(1-propenylthio)-L-cysteine), and (R)-2-amino-3-(2-propenyldisulfanyl)propanoic acid (S-allylthio-L-cysteine) were prepared from 3-[(methoxycarbonyl)dithio]-L-alanine, obtained from the reaction of L-cysteine with methoxycarbonylsulfenyl chloride. The occurrence of these S-(+)-alk(en)ylthio-L-cysteine derivatives in onion (Allium cepa L.) was proven by using UPLC-MS-ESI(+) in SRM mode. Their concentrations in fresh onion were estimated to be 0.19 mg/kg S-methylthio-L-cysteine, 0.01 mg/kg S-propylthio-L-cysteine, and 0.56 mg/kg (S-(1-propenyllthio)-L-cysteine, concentrations that are about 3000 times lower than that of isoalliin (S-(1-propenyl-S-oxo-L-cysteine). These compounds were treated with Fusobacterium nucleatum, a microorganism responsible for the formation of mouth malodor. These L-cysteine disulfides were demonstrated to predominantly produce tri- and tetrasulfides. Isoalliin is almost entirely consumed by the plant enzyme alliin lyase (EC 4.4.1.4 S-alk(en)yl-S-oxo-L-cysteine lyase) in a few seconds, but it is not transformed by F. nucleatum. This example of flavor modulation shows that the plant produces different precursors, leading to the formation of the same types of volatile sulfur compounds. Whereas the plant enzyme efficiently transforms S-alk(en)yl-S-oxo-L-cysteine, mouth bacteria are responsible for the transformation of S-alk(en)ylthio-L-cysteine.

Exploring natural products for new taste sensations.

This paper discusses the discovery of uncommon taste or trigeminal active compounds and their associated sensory analysis using human tasting panels with the aim of enhancing the overall taste experience whilst reducing where possible the sugar and salt content of foods. The first example outlines the discovery of the sensory quality attributes of (R)-2-(carboxymethylamino)propanoic acid, named (R)-strombine, as assessed by a panel of 47 subjects to confirm its contribution to the typical taste of scallop muscle. The second example discusses the pungency and trigeminal effect of polygodial, which is compared with piperine and capsaicin, as well as the elucidation of a new structure eliciting a trigeminal effect, (+/-)-trans-2,3,3a,7a-tetrahydro-1 H-indene-4-carbaldehyde, discovered in Amomum tsao-ko. Finally, the time intensity trigeminal effect of (-)-menthol is compared with (1R,2RS,4RS)-1-isopropyl-4-methylbicyclo[3.1.0]hexan-2-ol, named dihydroumbellulol, a new cooling compound obtained by hemi-synthesis from umbellulone extracted from Umbellularia californica Nutt.

New cysteine-S-conjugate precursors of volatile sulfur compounds in bell peppers (Capsicum annuum L. cultivar).

The objective of this study was to verify whether the volatile organic sulfur compounds recently discovered in bell pepper (Capsicum annuum, L. cultivars), such as the mercapto-ketones: 4-sulfanyl-2-heptanone and 2-sulfanyl-4-heptanone, the mercapto-alcohols: 4-sulfanyl-2-heptanol and 2-sulfanyl-4-heptanol, and heptane-2,4-dithiol, originate from their corresponding cysteine-S-conjugates. Analysis of aqueous extracts of red and green bell pepper by ultraperformance liquid chromatography-mass spectrometry with electrospray ionization in the positive mode (UPLC-MS ESI(+)) displayed masses corresponding to the expected cysteine-S-conjugates. To confirm this observation, four cysteine-S-conjugates were prepared as authentic samples: S-(3-hydroxy-1-methylhexyl)-L-cysteine, S-(3-hydroxy-1-propylbutyl)-L-cysteine, S-(3-oxo-1-propylbutyl)-L-cysteine, and (2R,2'R)-3,3'-(4-hydroxyheptane-2,6-diyl)bis(sulfanediyl) bis(2-aminopropanoic acid). By comparison with the fragmentation patterns and retention times of synthetic mixtures of cysteine-S-conjugate diastereoisomers, the natural occurrence of cysteine conjugates was confirmed in bell peppers. In addition, the cysteine-S-conjugates from red and green bell pepper extracts were concentrated by ion exchange chromatography and the fractions incubated with a ß-lyase (apotryptophanase). The liberated thiols were concentrated by affinity chromatography, and their occurrence, detected by gas chromatography-mass spectrometry, confirmed our predictions. Moreover, 3-sulfanyl-1-hexanol was also detected and the occurrence of S-(1(2-hydroxyethyl)butyl)-L-cysteine confirmed. A quantitative estimation based on external calibration curves, established by UPLC-MS ESI(+) in selected reaction monitoring mode, showed that cysteine-S-conjugates were present at concentrations in the range of 1 to 100 µg/kg (±20%).

Hemisynthesis of dihydroumbellulols from umbellulone: new cooling compounds.

Although menthol is a common ingredient used in food products, other molecules also evoke coolness through stimulation of the somatosensory system. To discover new molecules having cooling properties, we virtually screened the chemical structures of terpenes and sesquiterpenes to find structures that are similar to (-)-menthol. We realized that dihydroumbellulols could be good candidates. Although their occurrence was reported in Hyptis pectinata Poit, we were unable to obtain these molecules from the plant or to prove their natural occurrence. Therefore, we extracted (-)-(R)-umbellulone from Umbellularia californica Nutt. The (-)-(R)-umbellulone was reduced to prepare (1R,2R/S)-1-isopropyl-4-methylbicyclo[3.1.0]hex-3-en-2-ol, (1R,4R/S)-1-isopropyl-4-methylbicyclo[3.1.0]hexan-2-one, and (1R,2RS,4RS)-1-isopropyl-4-methylbicyclo[3.1.0]hexan-2-ols, named dihydroumbellulols. Sensory analysis suggested that (1R,2R,4S)-dihydroumbellulol has a pleasant, trigeminal cooling effect, about 2-3 times less cooling than (-)-menthol, with a weak odor slightly reminiscent of eucalyptol. In addition, a previously unreported compound was discovered, (-)-(1R)-1-isopropyl-4-methylenebicyclo[3.1.0]hexan-2-one.

Taste contribution of (R)-strombine to dried scallop.

A broth of dried scallop adductor muscles was prepared. Tasters appreciated the typical seafood, sweet, slightly umami taste of scallop, which is difficult to reproduce with common ingredients. Therefore, the broth was fractionated and, guided by multiple tastings, we isolated a sweet, umami, delicious fraction. This fraction contained glycine, alanine, and (R)-strombine ((R)-2-(carboxymethylamino)propanoic acid). (R) and (S)-strombine were prepared, and a sensory analysis with 47 judges demonstrated that the taste thresholds were 0.5 g/L for (R)-strombine and 0.7 g/L for (S)-strombine. The sensory attributes were described as salty and umami.

Gender-specific differences between the concentrations of nonvolatile (R)/(S)-3-methyl-3-sulfanylhexan-1-Ol and (R)/(S)-3-hydroxy-3-methyl-hexanoic acid odor precursors in axillary secretions.

The volatile fatty acid, (R)/(S)-3-hydroxy-3-methylhexanoic acid ((R)/(S)-HMHA), and the human specific volatile thiol, (R)/(S)-3-methyl-3-sulfanylhexan-1-ol ((R)/(S)-MSH), were recently identified as major components of human sweat malodor. Their 2 corresponding precursors were subsequently isolated from sterile and odorless axillary secretions. The purpose of this work was to analyze these 2 odor precursors in 49 male and female volunteers over a period of 3 years to elucidate to which extent they are implicated in the gender-specific character of body odor. Surprisingly, the ratio between the acid precursor 1, a glutamine conjugate, and the "sulfur" precursor 2, a cysteinylglycine-S-conjugate, was 3 times higher in men than in women with no correlation with either the sweat volume or the protein concentration. Indeed, women have the potential to liberate significantly more (R)/(S)-MSH, which has a tropical fruit- and onion-like odor than (R)/(S)-HMHA (possibly transformed into (E)/(Z)-3-methyl-2-hexenoic acid) that has a cheesy, rancid odor. Parallel to this work, sensory analysis on sweat incubated with isolated skin bacteria (Staphylococcus epidermidis Ax3, Corynebacterium jeikeium American Type Culture Collection 43217, or Staphylococcus haemolyticus Ax4) confirmed that intrinsic composition of sweat is important for the development of body odors and may be modulated by gender differences in bacterial compositions. Sweat samples having the highest sulfur intensity were also found to be the most intense and the most unpleasant.

Olfactory perception of cysteine-S-conjugates from fruits and vegetables.

Volatile sulfur compounds have a low odor threshold, and their presence at microgram per kilogram levels in fruits and vegetables influences odor quality. Sensory analysis demonstrates that naturally occurring, odorless cysteine- S-conjugates such as S-( R/ S)-3-(1-hexanol)- l-cysteine in wine, S-(1-propyl)- l-cysteine in onion, and S-(( R/ S)-2-heptyl)- l-cysteine in bell pepper are transformed into volatile thiols in the mouth by microflora. The time delay in smelling these volatile thiols was 20-30 s, and persistent perception of their odor occurred for 3 min. The cysteine- S-conjugates are transformed in free thiol by anaerobes. The mouth acts as a reactor, adding another dimension to odor perception, and saliva modulates flavors by trapping free thiols.

Structure elucidation of a pungent compound in black cardamom: Amomum tsao-ko Crevost et Lemarié (Zingiberaceae).

Natural plant extracts containing taste modifier compounds will gain more commercial interest in the future. Black cardamom, Amomum tsao-ko Crevost et Lemarié, used as a spice in Asia, produces a nice refreshing effect in the mouth. Therefore, an ethyl acetate extract was prepared, and constituents were separated by liquid chromatography. Guided by the tasting of each fraction (LC tasting), a new pungent compound was discovered, (+/-)-trans-2,3,3a,7a-tetrahydro-1H-indene-4-carbaldehyde. To confirm this new structure, a synthesis was performed starting from cyclopentene-1-carbaldehyde. The Wittig conditions were determined to control the stereochemistry of the ring fusion to prepare (+/-)-trans-(2,3,3a,7a-tetrahydro-1 H-inden-4-yl) methanol and (+/-)-cis-(2,3,3a,7a-tetrahydro-1H-inden-4-yl) methanol. After oxidation, (+/-)-trans-2,3,3a,7a-tetrahydro-1H-indene-4-carbaldehyde and (+/-)-cis-2,3,3a,7a-tetrahydro-1H-indene-4-carbaldehyde were tasted in water and only the trans-2,3,3a,7a-tetrahydro-1H-indene-4-carbaldehyde, present in black cardamom, produced a trigeminal effect in the mouth.

Volatile organic sulfur-containing constituents in Poncirus trifoliata (L.) Raf. (Rutaceae).

During our screening of plant materials to find new natural fragrance and flavor ingredients, we discovered two series of 3-sulfanylalkyl alkanoates in a peel extract of fruits of wild-growing Poncirus trifoliata (L.) Raf. (Rutaceae), a species closely related to Citrus. The two series belong to alkanoates of 3-methyl-3-sulfanylbutan-1-ol and 3-sulfanylhexan-1-ol, respectively, and thus are members of a family of natural molecules having in common a 1,3-positioned O,S moiety. The alkanoate residues comprise all even-numbered saturated fatty acids from C2 (acetate) to C18 (octadecanoate). Among the 20 sulfur-containing compounds identified, 14 are described for the first time as naturally occurring in a botanical species. Several cysteine-S-conjugates were synthesized as hypothetical precursors of the new volatile sulfur-containing constituents, where after S-(3-hydroxy-1,1-dimethylpropyl)-L-cysteine, S-[3-(acetyloxy)-1,1-dimethylpropyl]-L-cysteine, and S-[1-(2-hydroxyethyl)butyl]-L-cysteine were identified in the fruit peel. No cysteine-S-conjugates were detected in the fruit juice.