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Unlike many other named reactions in organic chemistry, the Maillard reaction is not a clearly defined single pathway. Instead, it is one of the most complex reactions in food chemistry. Maillard reactions, studied in the literature over the last fifty years, have focused either on simple model systems or complex culinary processes. The next step in our understanding of Maillard reactions is to bridge the gap between these simple and complex systems. By adding more than one amino acid to a model system, we aim to better understand the different mechanisms for which certain aroma compounds are formed. In this study, L-arginine and L-cysteine were selected as the two amino acids in the thermal reaction with glucose. Under different conditions, the key odorants from several arginine-cysteine/glucose model studies were identified and quantified by gas chromatography-mass spectrometry and gas chromatography-olfactometry.

Global production and demand for tropical fruits continues to grow each year as consumers are enticed by the exotic flavors and potential health benefits that these fruits possess. Volatile sulfur compounds (VSCs) are often responsible for the juicy, fresh aroma of tropical fruits. This poses a challenge for analytical chemists to identify these compounds as most often VSCs are found at low concentrations in most tropical fruits. The aim of this review is to discuss the extraction methods, enrichment techniques, and instrumentation utilized to identify and quantify VSCs in natural products. This will be followed by a discussion of the VSCs reported in tropical and subtropical fruits, with particular attention to the odor and taste attributes of each compound. Finally, the biogenesis and enzymatic formation of specific VSCs in tropical fruits will be highlighted along with the contribution each possesses to the aroma of their respective fruit. Keywords: Tropical fruits, Volatile sulfur compounds, Extraction methods

Thiols are often highly odor active molecules and as such can significantly contribute to aroma while being present at extremely low concentrations. This paper details the identification of thiols in yellow onion juice by solvent extraction followed by thiol enrichment using a mercuric agarose gel column. Due to the inherent thermal instability and low concentrations of thiols in onion, chromatographic analysis utilized larger volume solvent elimination injections. New sulfur compounds in onion included 1,1-propanedithiol, bis-(1-sulfanylpropyl)-sulfide, 1-methylsulfanyl-1-propanethiol, 1-propylsulfanyl-1-propanethiol, and 1-allylsulfanyl-1-propanethiol. A discussion on the potential route of formation for each compound is included along with the orthonasal and retronasal evaluations of the synthesized molecules. This work investigated and identified 5 newly identified compounds present in onions that can impart onion character at low concentrations levels.

Grown predominantly in France, Ciflorette strawberries (Fragaria × ananassa ‘Ciflorette’) possess a well-balanced fruity aroma and a sweet, creamy taste. The goal of this study was to better understand the chemical composition and key odourants of this unique fruit. Incorporating fractionation and multidimensional gas chromatography-mass spectrometry (MDGC-MS), the volatile constituents of Ciflorette strawberries are discussed for the first time from the large-scale extraction of 100 kg of the pureed berries. A total of 24 volatile sulphur compounds were either absolutely confirmed by synthesis or tentatively identified from the different analyses. Three sulphur compounds were synthesized and described in nature for the first time: 1-(methylthio)-2,3-butanedione, 3-(acetylthio)-hexanal and 2,6-dipropyl-3-formyl-5,6-dihydro-2H-thiopyran. Finally, GC-olfactometry (O) conducted by seven panelists led to the identification of 43 aroma-active compounds in the strawberry extract. Copyright © 2015 John Wiley & Sons, Ltd.

Lemons (Citrus limon) are a desirable citrus fruit grown and used globally in a wide range of applications. The main constituents of this sour-tasting fruit have been well quantitated and characterized. However, additional research is still necessary to better understand the trace volatile compounds that may contribute to the overall aroma of the fruit. In this study, Lisbon lemons (C. limon L. Burm. f. cv. Lisbon) were purchased from a grove in California, USA, and extracted by liquid-liquid extraction. Fractionation and multidimensional gas chromatography-mass spectrometry were utilized to separate, focus, and enhance unidentified compounds. In addition, these methods were employed to more accurately assign flavor dilution factors by aroma extract dilution analysis. Numerous compounds were identified for the first time in lemons, including a series of branched aliphatic aldehydes and several novel sulfur-containing structures. Rarely reported in citrus peels, sulfur compounds are known to contribute significantly to the aroma profile of the fruit and were found to be aroma-active in this particular study on lemons. This paper discusses the identification, synthesis, and organoleptic properties of these novel volatile sulfur compounds.

The isomers of 3,7-dimethyl-2,6-octadienal, more commonly known together as citral, are two of the most notable natural compounds in the flavor and fragrance industry. However, both isomers are inherently unstable, limiting their potential use in various applications. To identify molecules in nature that can impart the fresh lemon character of citral while demonstrating stability under acidic and thermal conditions has been a major challenge and goal for the flavor and fragrance industry. In the study of fried chicken, several alkyl thiophenecarbaldehydes were identified by gas chromatography-mass spectrometry and gas chromatography-olfactometry that provided a similar citral-like aroma. The potential mechanism of formation in fried chicken is discussed. Furthermore, in order to explore the organoleptic properties of this structural backbone, a total of 35 thiophenecarbaldehyde derivatives were synthesized or purchased for evaluation by odor and taste. Certain organoleptic trends were observed as the length of the alkyl or alkenyl chain increased or when the chain was moved to different positions on the thiophene backbone. The 3-substituted alkyl thiophenecarbaldehydes, specifically 3-butyl-2-thiophenecarbaldehyde and 3-(3-methylbut-2-en-1-yl)-2-thiophenecarbaldehyde, exhibited strong citrus and citral-like notes. Several alkyl thiophenecarbaldehydes were tested in high acid stability trials (4 °C vs 38 °C) and outperformed citral both in terms of maintaining freshness over time and minimizing off-notes. Additional measurements were completed to calculate the odor thresholds for a select group of thiophenecarbaldehydes, which were found to be between 4.7-215.0 ng/L in air.

The directed synthesis of two noncentrosymmetric sulfated molybdates has been achieved through the use of chiral organic amines. Reaction gels containing either (R)-2-methylpiperazine or (S)-2-methylpiperazine, MoO3, H2SO4, and H2O were subjected to mild hydrothermal conditions, resulting in the growth of single crystals of [(R)-C5H14N2][(MoO3)3(SO4)]·H2O and [(S)-C5H14N2][(MoO3)3(SO4)]·H2O. These materials crystallize in the noncentroysmmetric space group P212121 (No. 19), which exhibits the enantiomorphic crystal class 222 (D2). The second harmonic generation activities were measured on sieved powders.

Preface Overview 1. Overview of Flavors in Noncarbonated Beverages - Neil C. Da Costa, Theodore J. Anastasiou, and Jide Adedeji Tea 2. Characteristic Odorants of Sri Lankan Black Teas - Hisae Kasuga, Yuichiro Yamazaki, Aki Baba, and Sachiko Okajima 3. A Non-Volatile Study of Teas Using Modern Analytical and Sensory Techniques - Ying Yang, Jerry Kowalczyk, and Laurence Trinnaman 4. Functional Contribution of Polyphenols in Black Tea - Yu Wang and Chi-Tang Ho 5. LC Taste as a Tool for the Identification of Taste Modulating Compounds from Traditional African Teas - K. V. Reichelt, R. Peter, M. Roloff, J. P. Ley, G. E. Krammer, K. M. Swanepoel, and K.-H. Engel Coffee 6. The Key Odorants of Coffee from Various Geographical Locations - Robert J. Cannon, Laurence Trinnaman, Brian Grainger, and Amy Trail Citrus and Fruit Juice 7. Aroma Components of Fresh and Stored Pomegranate (Punica granatum L.) Juice - Keith R. Cadwallader, Lauren C. Tamamoto, and Stephanie C. Sajuti 8. Evaluation of Apple Juice Aroma - Carolin Wolter, Achim Gessler, and Peter Winterhalter 9. Effects of Processing and Storage on the Stability of Folate Vitamers and Pantothenic Acid in Sea Buckthorn Berries and Related Products (Hippophae rhamnoides L. ssp. rhamnoides) - Derek Gutzeit, Gerold Jerz, Michael Rychlik, Bernd Klaubert, and Peter Winterhalter 10. Processing Effects on the Flavor and Quality of Blueberries - Lisa L. Dean, Je'Velle B. Leavens, and Leon C. Boyd 11. Enhanced Stability of Citral in Juice Beverages by Applying Cyclodextrin Micro Emulsion Technology - Ken Strassburger, William Startup, Victor Levey, Tracey Mattingly, Judy Briggs, Joy Harrison, and Terry Wilson Alcoholic Beverages 12. Odorant Release from Alcoholic Beverages - Andrew J. Taylor, Maroussa Tsachaki, Ricardo Lopez, Cecile Morris, Vicente Ferreira, and Bettina Wolf 13. Analysis of Volatiles in Limoncello Liqueur and Aging Study with Sensory - Neil C. Da Costa and Theodore J. Anastasiou