Aroma Molecules Research Articles

An endophytic fungus associated with Kayea assamica (King & Prain): A study on its molecular phylogenetics and natural products

Endophytes; a ubiquitous group of microorganisms considered as a gem box of bioactive constituents of medical significance. Studies on this emerging field is very less among the research communities. The present study focused on the molecular phylogenetics of the endophytic fungus that associated with the leaf of Kayea assamica, an endemic plant species of Northeast India and identification of its secondary metabolites (natural product) that produced under in vitro condition. The endogenous fungus was isolated from the sterile disease-free leaf segment (1 cm), followed by PCR amplification of ITS region using the extracted genomic DNA as a template. Further, the crude methanol extract of the fungal culture was subjected to Gas Chromatography-Mass Spectrometry (GC–MS) analysis. The molecular phylogenetic analysis confirmed the fungal isolate as Beltraniella species (endophyte). The ITS sequence was submitted to GenBank database (Id MH295767.1). The GC-MS analysis revealed eleven different secondary metabolites at different retention times. Many of these compounds have been reported to be plant & endophytic metabolite, essential oil component, recognized fragrant molecule, antimicrobial, antioxidant, anticancer activities etc. The findings projected that the endophyte may have a significant role in the host-defense mechanism. Tetrapentacontane is a part of fragrant molecules found in juvenile agarwood shown highest abundance (54.63%) at 21.477 RT followed by the others. This study performed for the first time on endosymbiotic microorganism present in the respective plant species and highlighted this endophytic fungus as a unique source of non-plant based bioactive compounds with future biotechnological consequence.

Quantification of Residual Perfume by Py-GC-MS in Fragrance Encapsulate Polymeric Materials Intended for Biodegradation Tests

Perfume encapsulates are widely used in commercial products to control the kinetic release of odorant molecules, increase storage stability and/or improve deposition on different substrates. In most of the cases, they consist of core-shell polymeric microcapsules that contain fragrance molecules. A current challenge is to design and produce polymeric materials for encapsulation that are both resistant and non-persistent. The selection of such eco-friendly formulations is linked to a deep understanding of the polymeric material used for encapsulation and its biodegradation profile. To collect this information, pure samples of capsule shells are needed. In this article we present an innovative quantification method for residual volatiles based on pyrolysis-GC-MS to enable validation of sample quality prior to further testing. The presented analytical method also led to the development of a robust and comprehensive purification protocol for polymers from commercial samples. Standard techniques are not suited for this kind of measurement due to the non-covalent embedding of volatiles in the 3D structure of the polymers. We demonstrated the confounding impact of residual volatiles on the estimated biodegradability of fragrance encapsulates.

Zwitterionic comb-like lipid polymers encapsulating linalool for increasing the fragrance retention time

Fragrances are widely used in cosmetics, apparel and detergents. However, the rapid evaporation of the aroma shortens the useful life of the aromatic product. Therefore, improving the fragrance retention time of aromatic products and prolonging the service life of aromatic products are the key scientific problems that need to be solved in current aromatic products. In this study, zwitterionic comb-like lipid polymers were synthesized to encapsulate the fragrance molecule linalool. The results showed that the zwitterionic comb lipid molecules were capable of encapsulating more linalool than linear lipid molecules. At the same time, the zwitterionic comb-like lipid molecules also limited the slow release rate of the aroma, thereby increasing the fragrance retention time of the nano-fragrance.

Quantification of selected aroma compounds in e-cigarette products and toxicity evaluation in HUVEC/Tert2 cells.

During recent years, the number of consumers using so-called e-cigarettes, which are electrical devices to aerosolize a liquid consisting of propylene glycol, glycerol, optional nicotine and flavoring chemicals, has been increasing. Aromas vary from common flavors such as mint to more unusual flavors such as buttermilk or pepperoni pizza. Consumers today can buy e-concentrates that consist of propylene glycol and aroma to blend their own desired flavor at home. Little is known about the composition and concentration of various aroma molecules in the different e-liquids and e-concentrates. In addition, the process of EU-wide regulation is still ongoing. The aim of this research study was to identify and quantify possible undesirable aroma compounds in e-liquids and e-concentrates. Flavoring chemicals such as estragole, benzaldehyde and cinnamaldehyde were quantified. The measurements were carried out on a GC-MS system. The results show the presence of highly concentrated flavoring compounds and limonene oxide in lemon-flavored e-concentrates. In the final step, samples and single-aroma standards were tested for their toxicity to HUVEC/Tert2 cells, where some single-flavoring chemicals such as cinnamic aldehyde revealed significant toxic effects.

Design of fragrant molecules through the incorporation of rough sets into computer-aided molecular design

The design of fragrant molecules by combining rough set theory with property prediction models on a molecular signature platform.

The Actual and Potential Aroma of Winemaking Grapes.

This review intends to rationalize the knowledge related to the aroma of grapes and to the aroma of wine with specific origin in molecules formed in grapes. The actual flavor of grapes is formed by the few free aroma molecules already found in the pulp and in the skin, plus by those aroma molecules quickly formed by enzymatic/catalytic reactions. The review covers key aroma components of aromatic grapes, raisins and raisinized grapes, and the aroma components responsible from green and vegetal notes. This knowledge is used to explain the flavor properties of neutral grapes. The aroma potential of grape is the consequence of five different systems/pools of specific aroma precursors that during fermentation and/or aging, release wine varietal aroma. In total, 27 relevant wine aroma compounds can be considered that proceed from grape specific precursors. Some of them are immediately formed during fermentation, while some others require long aging time to accumulate. Precursors are glycosides, glutathionyl and cysteinyl conjugates, and other non-volatile molecules.

Plant derived secondary metabolites in cancer therapy: actions, applications, and future prospective of dietaryflavonol (quercetin)

Higher plants are prominent sources for several bioactive chemical constituents (secondary metabolites) who include photochemical, flavoring agents, fragrant molecules, and food additives. According to WHO estimates, it has been reported that more than 80% of population in developing countries prefer these natural bioactive active compounds for their primary health requirement. At present, conventional chemotherapy is constrained due to the nonselective toxicity to human organs and their usage is limited now a days. In a recent survey, more than 60% of cancer patients have been preferring adjuvant phototherapy along with chemotherapy. Thus, photochemical are being widely used as anticancer agents to target specific pathological pathways underlying cancer with low toxic profiles and side effects. These photochemical are cost-effective and easily accessible to the public to treat cancer diseases. These bioactive photochemical are meticulously belongs to secondary metabolites such as alkaloids, flavonoids, polyphenols.Among them, the flavonoids are polyphenolic substances, which are found in all parts of the plant such as flowers, fruits, leaves, roots, seeds, and bark. They possess high medicinal properties like being anti-cancer, anti-hypertensive, anti-inflammatory, anti-obesity, anti-malarial, antioxidant agents. Quercetin is major flavones associated with a profound antioxidant and medicinal property to prevent the oxidation of lipids in vitro and in vivo, and also exhibits direct proapoptotic effects on tumor cells. This compound has proven efficacy in targeting several cancer cells of breast, colon, prostate, ovarian, and lung tumor in vitro. The present review focuses on the effect of quercetin in cancer therapy.

Engineering of Saccharomyces cerevisiae for the production of (+)-ambrein.

The triterpenoid (+)-ambrein is the major component of ambergris, a coprolite of the sperm whale that can only be rarely found on shores. Upon oxidative degradation of (+)-ambrein, several fragrance molecules are formed, amongst them (-)-ambrox, one of the highest valued compounds in the perfume industry. In order to generate a Saccharomyces cerevisiae whole-cell biocatalyst for the production of (+)-ambrein, intracellular supply of the squalene was enhanced by overexpression of two central enzymes in the mevalonate and sterol biosynthesis pathway, namely the N-terminally truncated 3-hydroxy-3-methylglutaryl-CoA reductase 1 (tHMG) and the squalene synthase (ERG9). In addition, another key enzyme in sterol biosynthesis, squalene epoxidase (ERG1) was inhibited by an experimentally defined amount of the inhibitor terbinafine in order to reduce flux of squalene towards ergosterol biosynthesis while retaining sufficient activity to maintain cell viability and growth. Heterologous expression of a promiscuous variant of Bacillus megaterium tetraprenyl-β-curcumene cyclase (BmeTC-D373C), which has been shown to be able to catalyse the conversion of squalene to 3-deoxyachillol and then further to (+)-ambrein resulted in production of these triterpenoids in S. cerevisiae for the first time. Triterpenoid yields are comparable with the best microbial production chassis described in literature so far, the methylotrophic yeast Pichia pastoris. Consequently, we discuss similarities and differences of these two yeast species when applied for whole-cell (+)-ambrein production.

Aroma Molecules as Dynamic Volatile Surfactants: Functionality beyond the Scent.

Understanding of nonequilibrium processes at dynamic interfaces is indispensable for advancing design and fabrication of solid-state and soft materials. The research presented here unveils specific interfacial behavior of aroma molecules and justifies their usage as multifunctional volatile surfactants. As nonconventional volatile amphiphiles, we study commercially available poorly water-soluble compounds from the classes of synthetic and essential flavor oils. Their disclosed distinctive feature is a high dynamic interfacial activity, so that they decrease the surface tension of aqueous solutions on a time scale of milliseconds. Another potentially useful property of such amphiphiles is their volatility, so that they notably evaporate from interfaces on a time scale of seconds. This behavior allows for control of wetting and spreading processes. A revealed synergetic interfacial behavior of mixtures of conventional and volatile surfactants is attributed to a decrease of the activation barrier as a result of high statistical availability of new sites at the surface upon evaporation of the volatile component. Our results offer promising advantages in manufacturing technologies which involve newly creating interfaces, such as spraying, coating technologies, ink-jet printing, microfluidics, laundry, and stabilization of emulsions in cosmetic and food industry, as well as in geosciences for controlling aerosol formation.

Preparation of Gamma Polyglutamic Acid (Γ-PGA)/Gelation Composite Nanoparticle and Application on Osmanthus Fragrance Slow-Release

In order to extend the incense period, to improve the stability and processability of osmanthus fragrance. It has not reported to use γ-PGA/Gelatin nanoparticle preparate coated fragrance. This research used γ-PGA/Gelatin nanoparticles after embedding essence, observed its property index. γ-PGA/Gelatin nanoparticle was investigated with respect to its optimum experiment process and microencapsulation technology. Through coagulation precipitation, which is an ionic self-assembly process, a large amount obtained of non-toxic and edible. Thermogravimetric analysis uncovered that fragrance-γ-PGA/Gelatin nanoparticles were surprisingly well conserved at rapidly increasing temperature. E-nose measurement revealed fine stability of scent. The yield was obtained as 41.6g/L which increased by 32.9% under optimized conditions and less waste was created. As the temperature increased from 0°C to 200 °C, the coated fragrance lost only by 11% while bare fragrance molecules almost fully evaporated. The unchanged and stable scent and a superior ability of heat resistant were attributed to the nano-size effect of fine structure and good characteristics of the incorporation of γ-PGA and gelatin.

Improved Production and In Situ Recovery of Sesquiterpene (+)-Zizaene from Metabolically-Engineered E. coli.

The sesquiterpene (+)-zizaene is the direct precursor of khusimol, the main fragrant compound of the vetiver essential oil from Chrysopogon zizanioides and used in nearly 20% of men’s fine perfumery. The biotechnological production of such fragrant sesquiterpenes is a promising alternative towards sustainability; nevertheless, product recovery from fermentation is one of the main constraints. In an effort to improve the (+)-zizaene recovery from a metabolically-engineered Escherichia coli, we developed an integrated bioprocess by coupling fermentation and (+)-zizaene recovery using adsorber extractants. Initially, (+)-zizaene volatilization was confirmed from cultivations with no extractants but application of liquid–liquid phase partitioning cultivation (LLPPC) improved (+)-zizaene recovery nearly 4-fold. Furthermore, solid–liquid phase partitioning cultivation (SLPPC) was evaluated by screening polymeric adsorbers, where Diaion HP20 reached the highest recovery. Bioprocess was scaled up to 2 L bioreactors and in situ recovery configurations integrated to fermentation were evaluated. External recovery configuration was performed with an expanded bed adsorption column and improved (+)-zizaene titers 2.5-fold higher than LLPPC. Moreover, internal recovery configuration (IRC) further enhanced the (+)-zizaene titers 2.2-fold, whereas adsorption velocity was determined as critical parameter for recovery efficiency. Consequently, IRC improved the (+)-zizaene titer 8.4-fold and productivity 3-fold from our last report, achieving a (+)-zizaene titer of 211.13 mg L−1 and productivity of 3.2 mg L−1 h−1. This study provides further knowledge for integration of terpene bioprocesses by in situ product recovery, which could be applied for many terpene studies towards the industrialization of fragrant molecules.

Ti3 C2 MXene Paper for the Effective Adsorption and Controllable Release of Aroma Molecules.

Olfactory sensing and perception play an important role in people's daily lives and greatly affects senses, emotions, and behavior. In particular, the development of the controlled release of aroma enhances human's well-being and strengthens interactions with surroundings through olfactory display, especial when combined with visual and audial cues. Here, Ti3 C2 MXene plays a dual-function role as the adsorption site of aroma molecules and the heating source for the controlled release of aroma molecules. Due to abundant termination groups on the surface and the metallic nature, Ti3 C2 MXene provides abundant active sites for the interaction with aroma molecules; simultaneously, MXene can be electrically heated to thermally desorb the aroma molecules from the interaction sites. This approach eliminates the interface incompatibility issues between the heating source and the molecular encapsulation layer in conventional olfactory display system. This work presents the controlled release of the aroma molecule phenethyl alcohol (PA) using Ti3 C2 MXene paper. Ti3 C2 MXene paper serves as the adsorption material and a heating source that achieves 100 °C within 1 s. The relative amount of PA released reaches nearly 100% after 1 min of heating.

Photocontrollable Release with Coumarin-Based Profragrances.

The achievement of controllable and lasting scent on a targeted surface is a long-term goal in the field of flavors and fragrances. Herein, we design a novel series of phototriggered coumarin-based profragrances conjugated with volatile carboxylic fragrances via activatable chemical bridge of ester group, thereby achieving the controllable release of volatile fragrances under ambient conditions. Upon exposure to light, the fragile ester group of profragrances allows the slow release of fragrance molecules, building up a new light-sensitive fragrance delivery system. The incorporated coumarin unit of CM-OH as phototrigger is killing two birds with one stone, that is, precise photocontrollable release of fragrance molecules, and unprecedented fluorescence intensity to monitor the releasing process of fragrance molecules with linear relationship (R2 > 0.95). In comparison, the light-induced releasing amount from profragrances of CM-O-EA, CM-O-PEA, CM-O-PA, and CM-O-CA is much lower than corresponding free fragrances by 33-, 8.5-, 13-, and 983-fold, respectively. As demonstrated, the coumarin-based profragrances provide a phototriggered platform to realize the controllable release of volatile fragrances, resulting in a long-lasting headspace concentration on the targeted surface of wallpaper.

Adsorption and Desorption of Organic Molecules From Thin Cellulose Films

The debate on environmental effects of everyday packaging materials has long reached the scientific community. The quest is on to design cheap, but also sustainable and eco - friendly packaging solutions. A hot contestant material within the application is the ever present wood based paper. In addition to meeting logistic requirements, paper packaging must protect the packaged goods from environmental influences, while keeping aroma molecules in the food. To quantify both aspects in depth, exploration of adsorption of organic molecules on paper is required. As paper is a rather complex material, adsorption and desorption experiments can be notoriously difficult to interpret. This paper will demonstrate that the adsorption of organic molecules on a cellulose surface can be investigated simply? by using temperature programmed desorption (TPD) experiments. The experiments show that both non-polar and polar molecules (n-decane and deuterated methanol) readily adsorb onto cellulose films. During desorption one finds the polar molecule bound to the cellulose surface more heavily, effectively oder doch strongly? than the non-polar molecule.

The Scent of Stress: Evidence From the Unique Fragrance of Agarwood.

Agarwood (Aquilaria spp.) fragrance and its origin in stress make it probably the most suitable model to study stress-induced aroma. Production being confined only to certain small pockets of South and Southeast Asia, agarwood is arguably the costliest wood in the world. Formation of fragrant agarwood resin is the outcome of complex biotic, abiotic, and physical stress on the Aquilaria trees. The intricate mechanism by which some 150 odd fragrant molecules that constitute agarwood aroma is formed is still not clearly understood. The present review therefore aims to bring to focus this less known but highly valuable stress-induced aroma from Asia. Discussions on agarwood species, occurrence, distribution, formation, and products have been included as foundation. Although global trade in agarwood and its products is estimated at US$6 billion to US$8 billion, no reliable data are readily available in literature. Therefore, an effort has been made to review the current status of agarwood trade. The element of stress and its correlation to agarwood aroma is discussed in the subsequent sections. Natural agarwood formation as well as technologies and interventions in agarwood induction are stress-based (natural and artificial injury, insect and fungal attack, chemical induction). The molecular triggers are gradually coming to light as new studies are implicating jasmonate, LOX signaling, and other stress reaction routes as the source of agarwood aroma. This review therefore has strived to compile the information that is scattered across scientific as well as other authentic literature and update the reader on the current status. More information about the specific roles of other vital stressors like insects, abiotic, and genetic factors is eagerly awaited from ongoing and future research to further understand the unique fragrance of agarwood.

Modulating the Precursor and Terpene Synthase Supply for the Whole-Cell Biocatalytic Production of the Sesquiterpene (+)-Zizaene in a Pathway Engineered E. coli

The vetiver essential oil from Chrysopogon zizanioides contains fragrant sesquiterpenes used widely in the formulation of nearly 20% of men’s cosmetics. The growing demand and issues in the supply have raised interest in the microbial production of the sesquiterpene khusimol, the main compound of the vetiver essential oil due to its woody smell. In this study, we engineered the biosynthetic pathway for the production of (+)-zizaene, the immediate precursor of khusimol. A systematic approach of metabolic engineering in Escherichia coli was applied to modulate the critical bottlenecks of the metabolic flux towards (+)-zizaene. Initially, production of (+)-zizaene was possible with the endogenous methylerythritol phosphate pathway and the codon-optimized zizaene synthase (ZS). Raising the precursor E,E-farnesyl diphosphate supply through the mevalonate pathway improved the (+)-zizaene titers 2.7-fold, although a limitation of the ZS supply was observed. To increase the ZS supply, distinct promoters were tested for the expression of the ZS gene, which augmented 7.2-fold in the (+)-zizaene titers. Final metabolic enhancement for the ZS supply by using a multi-plasmid strain harboring multiple copies of the ZS gene improved the (+)-zizaene titers 1.3-fold. The optimization of the fermentation conditions increased the (+)-zizaene titers 2.2-fold, achieving the highest (+)-zizaene titer of 25.09 mg L−1. This study provides an alternative strategy to enhance the terpene synthase supply for the engineering of isoprenoids. Moreover, it demonstrates the development of a novel microbial platform for the sustainable production of fragrant molecules for the cosmetic industry.

Graphene oxide–silica hybrid capsules for sustained fragrance release

Encapsulation of active or valuable cargoes has become one of the most important methods for controlled delivery and release. However, many existing capsule technologies suffer from scalability issues, and capsules from surfactant- or polymer-stabilised emulsions tend to have weak shells or limited stability. Here we present a robust and scalable method for the surfactant-free preparation of silica hybrid capsules templated from Pickering emulsions stabilised by graphene oxide. These capsules are produced using a single step, undemanding formulation process with cheap and scalable precursors. The mechanical and chemical stability provided by the silica shell grown around these droplets is explored using surface pressure measurements and atomic force microscopy, demonstrating that a rigid and robust capsule is produced from higher loadings of silica precursor. In order to demonstrate the utility of these capsules, the sustained release of a fragrance molecule (vanillin) from the capsules is monitored, and compared to release from unencapsulated vanilla oil. It is seen that the capsules retain the fragrance for multiple weeks, offering new pathways for scalable encapsulation systems for the delivery of valuable actives.

Application of Sulfated Tin (IV) Oxide Solid Superacid Catalyst to Partial Coupling Reaction of α-Pinene to Produce Less Viscous High-Density Fuel

Brønsted acid-catalyzed reactions of α-pinene have been studied because of their ability to produce various types of fragrance molecules. Beyond this application, dimeric hydrocarbon products produced from coupling reactions of α-pinene have been suggested as renewable high-density fuel molecules. In this context, this paper presents the application of a sulfated tin(IV) oxide catalyst for the partial coupling reaction of α-pinene from turpentine. Brønsted acid sites inherent in this solid superacid catalyst calcined at 550 °C successfully catalyzed the reaction, giving the largest yield of dimeric products (49.6%) at 120 °C over a reaction time of 4 h. Given that the low-temperature viscosity of the mentioned dimeric products is too high for their use as a fuel in transportation engines, lowering the viscosity is an important avenue of study. Therefore, our partial coupling reaction of α-pinene provides a possible solution as a considerable amount of the isomers of α-pinene still remained after the reaction, which reduces the low-temperature viscosity. On the basis of a comparison of the reaction products, a plausible mechanism for the reaction involving coinstantaneous isomerization and coupling reaction of α-pinene was elucidated.

Tea aroma formation from six model manufacturing processes

Tea aroma is determined by the nature of the plant, the production processes, and many other factors influencing its formation and release. The objective of this study was to investigate the impact of manufacturing processes on the aroma composition of tea. Fresh tea leaves from the same cultivar and growing area were selected for producing the six types of tea: green, white, yellow, oolong, black, and dark teas. Comprehensive analysis by gas chromatography mass spectrometry (GC/MS) was performed for the volatiles of tea infusion, prepared by solid-phase microextraction (SPME), solid-phase extraction (SPE), and solvent assisted flavor evaporation (SAFE). A total of 168 volatile compounds were identified. Black tea has the highest volatile concentration of 710 µg/g, while green tea has the lowest concentration of 20 µg/g. Significantly affected by these processes, tea aroma molecules are formed mainly from four precursor groups: carotenoids, fatty acids, glycosides, and amino acids/sugars.

Advances in preparation and controlled release of profragrances under ambient conditions

Profragrances referred to the controlled release system, in which the fragrance molecules and the specific substrates are linked by the characteristic responsive bonding. Profragrances can release fragrances under mild reaction conditions. The controlled release property of profragrances can prolong the scented perception caused by the high volatility of the fragrance molecules, thereby satisfying the demands of many flavored products, especially in requiring long-lasting odor. Due to most flavored products are used in daily life, the controlled release of fragrances based on environmental conditions is given great attention. This review focuses on the preparation and controlled release of profragrances under mild environmental conditions, especially the profragrances with different pH-response or photo-response, as well as briefly introduce the unusual oxygen-response profragrances. Furthermore, it gives a new insight into the future direction of the design and research of profragrances.