Special Issue "Flavors and Fragrances"
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A special issue of Molecules (ISSN 1420-3049).
Deadline for manuscript submissions: closed (31 March 2013)
Special Issue Editor
Guest Editor
Dr. Derek J. McPhee
Director of Chemistry, Amyris Biotechnologies, Inc., 5885 Hollis St, Suite 100, Emeryville, CA 94608, USA
E-Mail: mcphee@mdpi.com
Phone: +1 510 450 0761 xt 718
Fax: +1 510 225 2645
Interests: organic synthesis; medicinal chemistry; biotechnology
Special Issue Information
Submission
Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. Papers will be published continuously (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.
Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are refereed through a peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Molecules is an international peer-reviewed Open Access monthly journal published by MDPI.
Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs).
Published Papers (10 papers)
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Received: 25 October 2012; in revised form: 30 November 2012 / Accepted: 3 December 2012 / Published: 5 December 2012
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Abstract: The application of the exopolysaccharide-producing strains for improving the texture and technical properties of reduced-fat cheese looks very promising. Streptococcus thermophilus TM11 was evaluated for production of reduced-fat cheese using reconstituted milk powder (CRMP). The physicochemical analysis of fresh and stored cheeses showed that this strain slightly increased moisture content resulting in cheese with higher yield and lower protein content compared to the direct acidified cheese. The volatiles of cheese were determined by SPME and GC equipped with a mass spectrometer. The results indicated that the major compounds included aldehydes, ketones and acids, whereas, alcohols and branched-chain aldehydes that contribute to exciting and harsh flavors were not found in CRMP. By the textural profile analysis, we found the cheese made with S. thermophilus TM11 had lower cohesiveness, resilience and higher adhesiveness than the direct acidified cheese, and had similar hardness. Further, S. thermophilus TM11 greatly changed the protein matrix with more opened cavities according to observation by scanning electron microscopy. Consequently, use of S. thermophilus TM11 could endow CRMP with the novel and suitable flavor properties and improved texture quality.
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Received: 13 December 2012; in revised form: 21 February 2013 / Accepted: 21 February 2013 / Published: 27 February 2013
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Abstract: The aim of this study was to determine volatile compounds in dry dog foods and their possible influence on sensory aromatic profile. Grain-free dry dog foods were compared to dry dog foods manufactured with grain, but also with different protein sources for their aromatic volatiles. Solid-phase microextraction/gas chromatography/mass spectrometry was used to determine the aromatic compounds present in the headspace of these samples. Partial Least Squares regression was performed to correlate the instrumental aromatic data with the descriptive aroma analysis data. A total of 54 aromatic compounds were tentatively identified in the dry dog food samples, with aldehydes and ketones being the most represented organic volatiles group. Grain-added products were on the average higher in total volatiles than grain-free products. Partial Least Squares regression analysis indicated possible connections with sensory aromatic profile and grain-added samples, such as rancid aroma and aldehydes, especially hexanal. The results of this study showed that dry dog foods are products with complex odor characteristics and that grain-free products are less aromatic.
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Yangyang Liu, Huaiqiong Chen, Yun Yang, Zheng Zhang, Jianhe Wei, Hui Meng, Weiping Chen, Jindong Feng, Bingchun Gan, Xuyu Chen, Zhihui Gao, Junqin Huang, Bo Chen and Hongjiang Chen
Received: 30 November 2012; in revised form: 22 January 2013 / Accepted: 26 February 2013 / Published: 7 March 2013
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Abstract: Agarwood is the fragrant resin-infused wood derived from the wounded trees of Aquilaria species. It is a valuable non-timber forest product used in fragrances and as medicine. Reforestation for Aquilaria trees in combination with artificial agarwood-inducing methods serves as a way to supply agarwood and conserve of wild Aquilaria stock. However, the existing agarwood-inducing methods produce poor-quality agarwood at low yield. Our study evaluated a novel technique for producing agarwood in cultivated Aquilaria trees, called the whole-tree agarwood-inducing technique (Agar-Wit). Ten different agarwood inducers were used for comparison of Agar-Wit with three existing agarwood-inducing methods. For Aquilaria trees treated with these ten inducers, agarwood formed and spread throughout the entire tree from the transfusion point in the trunk to the roots and branches of the whole tree. Agarwood yield per tree reached 2,444.83 to 5,860.74 g, which is 4 to 28 times higher than that by the existing agarwood-inducing methods. Furthermore, this agarwood derived from Agar-Wit induction was found to have a higher quality compared with the existing methods, and similar to that of wild agarwood. This indicates Agar-Wit may have commercial potential. Induction of cultivated agarwood using this method could satisfy the significant demand for agarwood, while conserving and protecting the remaining wild Aquilaria trees.
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Received: 25 January 2013; in revised form: 6 March 2013 / Accepted: 8 March 2013 / Published: 13 March 2013
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Abstract: Humans can detect and discriminate a vast number of odours. The number perceived as distinguishable is estimated to be more than ten thousand. Humans are capable of distinguishing even slight alterations in the structure of an odorous molecule. A pair of enantiomers of an odorant, which possess the same molecular structures except for the chiral position, can trigger profoundly different odour perceptions. How precisely can humans and their olfactory system detect and discriminate such a great variety of odours and such subtle differences in the molecular structures? In a series of studies, we have attempted to examine the relationship between mood change, odour and its physiological effects, by focusing on the possible verbal and non-verbal changes in humans induced by smelling the fragrances of essential oils as well as linalool and its enantiometric isomers. In this article, we provide an overview of our recent verbal and non-verbal studies. We then discuss how our findings may contribute to the assessment of psychophysiological responses of essential oils as well as how our research can contribute to the study of human chemoreception science, by shedding light on the sophistication of the olfactory system in its ability to detect and discriminate odors.
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Received: 27 February 2013; in revised form: 28 March 2013 / Accepted: 28 March 2013 / Published: 3 April 2013
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Abstract: The flavor of dry cured ham explains the high appreciation of this product and it determines consumer acceptance. Volatile compounds provide valuable information about the odor and sensory quality of dry cured hams. Since amino acids are the origin of some volatile compounds of dry cured ham, the volatile and amino acid compositions of forty-one dry cured hams from Spain and France were determined to establish associations between them. The samples included different pig breeds (non Iberian vs. Iberian), which were additionally affected by different maturation times and feeding types (acorn vs. fodder). Results showed that 20 volatile compounds were able to distinguish Iberian and non Iberian hams, and 16 of those had relevant sensory impact according to their odor activity values. 3-Methylbutanol, 2-heptanol and hexanal were among the most concentrated volatile compounds. In the case of non-volatile compounds, the concentrations of amino acids were generally higher in Iberian hams, and all the amino acids were able to distinguish Iberian from non Iberian hams with the exception of tryptophan and asparagine. A strong correlation of some amino acids with volatile compounds was found in the particular case of alcohols and aldehydes when only Iberian hams were considered. The high correlation values found in some cases proved that proteolysis plays an important role in aroma generation.
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Received: 29 March 2013; in revised form: 12 April 2013 / Accepted: 19 April 2013 / Published: 25 April 2013
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Abstract: Attempts to relate sensory analysis data to specific chemicals such as volatile compounds have been frequent. Often these associations are difficult to interpret or are weak in nature. Although some difficulties may relate to the methods used, the difficulties also result from the complex nature of flavor. For example, there are multiple volatiles responsible for a flavor sensation, combinations of volatiles yield different flavors than those expected from individual compounds, and the differences in perception of volatiles in different matrices. This review identifies some of the reasons sensory analysis and instrumental measurements result in poor associations and suggests issues that need to be addressed in future research for better understanding of the relationships of flavor/aroma phenomena and chemical composition.
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Received: 15 April 2013; in revised form: 2 May 2013 / Accepted: 6 May 2013 / Published: 8 May 2013
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Abstract: Changes in the volatile components of unpasteurized and pasteurized makgeolli during 30 days of storage were investigated by gas chromatography-mass spectrometry (GC-MS) and GC-olfactometry (GC-O). A total of 11 odor-active compounds such as 3-methyl-1-butanol (isoamyl alcohol), 2-methyl-1-butanol, 2,3-butanediol, butanoic acid, 3-methylbutanoic acid (isovaleric acid), 2-methylbutanoic acid, 3-(methylthio)-1-propanol (methionol), 2-phenylethanol, ethyl decanoate, ethyl dodecanoate, and ethyl tetradecanoate were determined in both the pasteurized and unpasteurized makgeolli during 30 days of storage. Although there were no significant differences in the concentrations of odor-active compounds at the initial storage time, most of odor-active compounds were more significantly increased in unpasteurized makgeolli compared to the pasteurized one during the storage period.
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Received: 15 March 2013; in revised form: 21 April 2013 / Accepted: 6 May 2013 / Published: 10 May 2013
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Abstract: The fragrant camphor tree (Cinnamomum camphora) and its products, such as camphor oil, have been coveted since ancient times. Having a rich history of traditional use, it was particularly used as a fumigant during the era of the Black Death and considered as a valuable ingredient in both perfume and embalming fluid. Camphor has been widely used as a fragrance in cosmetics, as a food flavourant, as a common ingredient in household cleaners, as well as in topically applied analgesics and rubefacients for the treatment of minor muscle aches and pains. Camphor, traditionally obtained through the distillation of the wood of the camphor tree, is a major essential oil component of many aromatic plant species, as it is biosynthetically synthesised; it can also be chemically synthesised using mainly turpentine as a starting material. Camphor exhibits a number of biological properties such as insecticidal, antimicrobial, antiviral, anticoccidial, anti-nociceptive, anticancer and antitussive activities, in addition to its use as a skin penetration enhancer. However, camphor is a very toxic substance and numerous cases of camphor poisoning have been documented. This review briefly summarises the uses and synthesis of camphor and discusses the biological properties and toxicity of this valuable molecule.
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Received: 29 March 2013; in revised form: 29 April 2013 / Accepted: 10 May 2013 / Published: 16 May 2013
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Abstract: As part of a program aiming at the selection of yeast strains which might be of interest as sources of natural flavours and fragrances, the bioreduction of (4R)-(−)-carvone and (1R)-(−)-myrtenal by whole-cells of non-conventional yeasts (NCYs) belonging to the genera Candida, Cryptococcus, Debaryomyces, Hanseniaspora, Kazachstania, Kluyveromyces, Lindnera, Nakaseomyces, Vanderwaltozyma and Wickerhamomyces was studied. Volatiles produced were sampled by means of headspace solid-phase microextraction (SPME) and the compounds were analysed and identified by gas chromatography–mass spectroscopy (GC-MS). Yields (expressed as % of biotransformation) varied in dependence of the strain. The reduction of both (4R)-(−)-carvone and (1R)-(−)-myrtenal were catalyzed by some ene-reductases (ERs) and/or carbonyl reductases (CRs), which determined the formation of (1R,4R)-dihydrocarvone and (1R)-myrtenol respectively, as main flavouring products. The potential of NCYs as novel whole-cell biocatalysts for selective biotransformation of electron-poor alkenes for producing flavours and fragrances of industrial interest is discussed.
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Received: 22 February 2013; in revised form: 2 May 2013 / Accepted: 15 May 2013 / Published: 21 May 2013
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Abstract: The aim of this work was to gain insight into the effect of food formulation on aroma release and perception, both of which playing an important role in food appreciation. The quality and quantity of retronasal aroma released during food consumption affect the exposure time of olfactory receptors to aroma stimuli, which can influence nutritional and hedonic characteristics, as well as consumption behaviors. In yogurts, fruit preparation formulation can be a key factor to modulate aroma stimulation. In this context, the impact of size and hardness of fruit pieces in fat-free pear yogurts was studied. Proton Transfer Reaction-Mass Spectrometry (PTR-MS) was used to allow sensitive and on-line monitoring of volatile odorous compound release in the breath during consumption. In parallel, a trained panel used sensory profile and Temporal Dominance of Sensations (TDS) methods to characterize yogurt sensory properties and their dynamic changes during consumption. Results showed that the size of pear pieces had few effects on aroma release and perception of yogurts, whereas fruit hardness significantly influenced them. Despite the fact that yogurts presented short and similar residence times in the mouth, this study showed that fruit preparation could be an interesting formulation factor to enhance exposure time to stimuli and thus modify food consumption behaviors. These results could be taken into account to formulate new products that integrate both nutritional and sensory criteria.
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Planned Papers
The below list represents only planned manuscripts. Some of these
manuscripts have not been received by the Editorial Office yet. Papers
submitted to MDPI journals are subject to peer-review.
Type of Paper: Review
Tentative Title: Supercritical Fluid Extraction of Plant Flavors and Fragrances
Authors: Andrea Occhipinti, Andrea Capuzzo and Massimo E. Maffe
Affiliation: Department of Life Sciences and Systems Biology, University of Turin, Via Quarello 11/A, 10135 Turin, Italy
Abstract: Supercritical fluid extraction (SFE) of plant material with gases like CO2, propane, butane, or ethylene is a topic of growing interest. SFE allows the processing of plant material at low temperatures, hence limiting thermal degradation, and avoids the use of toxic solvents. The published articles on the usage of SFE mostly for pharmaceutical and food processing accounts for about 45% of the specific scientific literature, the remaining percentage being made by articles dealing with extractions with solvents (about 20%), microwave assisted extraction (MAE, about 10%), ultrasound-assisted extraction (UAE, about 10%) and other extraction techniques which are not yet used for industrial applications in large scale (about 10%). Although today SFE is mainly used for decaffeination of coffee and tea as well as production of hop extracts on large scale, there is a growing interest on this extraction method also for other industrial applications operating at different scales. This review describes the SFE technology at both industrial and laboratory scales and gives an overview of its potential in the flavors and fragrances arena.
Type of Paper: Article
Title: Production of Flavours and Fragrances via Bioreduction of Cyclic Ketones and Aldehydes by Non-Conventional Yeast Whole-Cells
Authors: M. Goretti 1, B. Turchetti 1, M. R. Cramarossa 2, L. Forti 2 and P. Buzzini 1
Affiliation: 1 Department of Applied Biology & Industrial Yeasts Collection DBVPG, University of Perugia, Italy
2 Department of Life Sciences, University of Modena & Reggio Emilia, Italy
Abstract: As a part of a program aiming at the selection of yeast strains which might be of interest as sources of natural flavouring molecules, the production of flavours and fragrances via bioreduction of α-β unsaturated cyclic ketones [(4R)-()-carvone] and aldehydes [(1R)()-myrtenal] by non-conventional yeasts (NCYs), belonging to the genera Candida, Cryptococcus, Debaryomyces, Hanseniaspora, Kazachstania, Kluyveromyces, Lindnera, Nakaseomyces, Vanderwaltozyma, and Wickerhamomyces, isolated from the environment was investigated. Volatiles produced were sampled by means of headspace solid-phase microextraction (SPME) and the compounds were analysed and identified by gas chromatography–mass spectroscopy (GC–MS). Yields (expressed as % of biotransformation) varied in dependence of the strain. The reduction of both (4S)()-carvone and R)()-myrtenal were catalyzed by some enoate reductases and/or carbonyl reductases, which determined the formation of (1R,4R)-dihydrocarvone and [(1R)()-myrtenol respectively, as main flavouring products. The potential of NCYs as whole-cell biocatalysts for selective biotransformation of electron-poor alkenes for producing flavours and fragrances of industrial interest is discussed.
Type of Paper: Article
Title: Electrochemical Oxidation of Fragrances 4-Allylbenzences and 4-Propenylbenzences on the Platinum and Carbon Paste Electrodes: A Comparative Account
Authors: Lai-Hao Wang*, Yi-Chun,Hu
Affiliation: Department of Medical Chemistry, Chia Nan University of Pharmacy and Science, 60 Erh-Jen Road, Section 1, Jen Te, Tainan 71743, Taiwan.
Abstract: The electrochemical oxidation behaviors of 4-allylbenzences (estragole and safrole) and 4-propenylbenzences (anethole and asarone) on platinum and carbon paste electrodes were investigated in a Britton-Robinson buffer (pH 1.93 -6.42), acetate buffer, phosphate buffer solutions (pH 2.08) and methanol or acetonitrile containing various supporting electrolytes. Their oxidation potential with Hammett (free-energy relationships) and possible mechanisms were discussed.
Last update: 21 February 2013
