Floral Scent Research Articles

The role of oak wood in the mint and floral notes of whisky: identification of common terpenoids by aromatic fractionation

Understanding the development of the whisky aroma during maturation in oak casks provides a rational basis for improvements in product quality. While oak wood is an important contributor to the spicy, toasted, and smoky aromatic notes, limited studies have focused on its role in floral and mint notes of matured whiskies. However, achieving consistent flavour profiles remains difficult since the odorant molecules are mostly present in low concentration. A semi-preparative ultra-high-performance liquid chromatography (UHPLC) method was applied to whisky and oak wood extracts and used to isolate fractions characterised by floral and mint aromas. To investigate the contribution of terpenoids in these floral and fresh fragrances, a similar analytical process was applied on solutions of targeted reference compounds. This approach, coupled to gas-chromatography/mass-spectrometry analyses, indicated the presence of terpenoids in the fractions of interest as well as selective separation according to chemical structure (i.e., monoterpenes, monoterpenols, ketone monoterpenes, and C13-norisoprenoids). This approach resulted in the detection of respectively, ten and seven new terpenoids in whisky and oak wood. To the best of our knowledge, piperitone, mintlactones, and

Volatile secondary metabolome and transcriptome analysis reveals distinct regulation mechanism of aroma biosynthesis in Syringa oblata and S. vulgaris

Lilacs have high ornamental value due to their strong aroma. However, the molecular regulatory mechanisms of aroma biosynthesis and metabolism in lilac were largely unclear. In this study, two varieties with distinct aroma, Syringa oblata ‘Zi Kui’ (faint aroma) and Syringa vulgaris ‘Li Fei’ (strong aroma), were used for exploring the regulation mechanism of aroma difference. Via GC-MS analysis, a total of 43 volatile components were identified. Terpene volatiles was the most abundant volatiles constituting the aroma of two varieties. Notably, 3 volatile secondary metabolites were unique in ‘Zi Kui’ and 30 volatile secondary metabolites were unique in ‘Li Fei’. Then, a transcriptome analysis was performed to clarify the regulation mechanism of aroma metabolism difference between these two varieties, and identified 6411 differentially expressed genes (DEGs). Interestingly, ubiquinone and other terpenoid-quinone biosynthesis genes were significantly enriched in DEGs. We further conducted a correlation analysis between the volatile metabolome and transcriptome and found that TPS, GGPPS, and HMGS genes might be the key contributors to the differences in floral fragrance composition between the two lilac varieties. Our study improves the understanding in the regulation mechanism of Lilac aroma and would help improve the aroma of ornamental crops by metabolic engineering.

Floral Scents in Bee-Pollinated Buckwheat and Oilseed Rape under a Global Warming Scenario.

Many wild plants and crops are pollinated by insects, which often use floral scents to locate their host plants. The production and emission of floral scents are temperature-dependent; however, little is known about how global warming affects scent emissions and the attraction of pollinators. We used a combination of chemical analytical and electrophysiological approaches to quantify the influence of a global warming scenario (+5 °C in this century) on the floral scent emissions of two important crop species, i.e., buckwheat (Fagopyrum esculentum) and oilseed rape (Brassica napus), and to test whether compounds that are potentially different between the treatments can be detected by their bee pollinators (Apis mellifera and Bombus terrestris). We found that only buckwheat was affected by increased temperatures. Independent of temperature, the scent of oilseed rape was dominated by p-anisaldehyde and linalool, with no differences in relative scent composition and the total amount of scent. Buckwheat emitted 2.4 ng of scent per flower and hour at optimal temperatures, dominated by 2- and 3-methylbutanoic acid (46%) and linalool (10%), and at warmer temperatures threefold less scent (0.7 ng/flower/hour), with increased contributions of 2- and 3-methylbutanoic acid (73%) to the total scent and linalool and other compounds being absent. The antennae of the pollinators responded to various buckwheat floral scent compounds, among them compounds that disappeared at increased temperatures or were affected in their (relative) amounts. Our results highlight that increased temperatures differentially affect floral scent emissions of crop plants and that, in buckwheat, the temperature-induced changes in floral scent emissions affect the olfactory perception of the flowers by bees. Future studies should test whether these differences in olfactory perception translate into different attractiveness of buckwheat flowers to bees.

Pollination biology of Sicyos angulatus: An invasive plant primarily pollinated by the native insects and introduced honeybee Apis mellifera

AbstractBurcucumber (Sicyos angulatus), first introduced in 1952 from North America to Japan, has recently become a seriously invasive alien species that has spread nationwide. The pollination mode is likely to play a crucial role in seed production and invasion. Burcucumbers have been characterized as self‐compatible flowers with distinct anthers and stigmas, indicating pollen vector‐mediated pollination. In this study, we aimed to describe the floral biology of burcucumbers and clarify their relationships with pollinators. We found that: (1) primarily native insects (at least 70 species) repeatedly visited burcucumbers, both during the day and night; (2) in terms of visitation frequency and pollen‐carrying load, honeybees, vespid wasps, and hoverflies were the most important diurnal pollinators, followed by sphingid and noctuid moths as nocturnal ones; and (3) the production of highly concentrated nectar as floral reward coupled with floral scents, predominantly aliphatic compounds such as heptanal and hexanol, may mediate the visitation of floral visitors. Our observations confirmed that burcucumber visitation is dominated by native pollinators, indicating the integration of burcucumbers into native pollinator webs. Our findings highlight the significance of a generalized pollination system in alien plants to overcome reproductive failure within a new region.

The Influence of Different Non-Conventional Yeasts on the Odour-Active Compounds of Produced Beers

The interest in new beer products, which has been growing for several years, forces technologists and brewers to look for innovative raw materials, such as hops, new sources of carbohydrates or yeast. The aim of the presented study was to evaluate the effect of selected Saccharomyces (Saccharomyces paradoxus (CBS 7302), S. kudriavzevii (CBS 3774), S. cerevisiae (Safbrew T-58)) and non-Saccharomyces yeast (W. anomalus (CBS 5759), Ha. uvarum (CBS 2768), D. bruxellensis (CBS 3429), Z. bailii (CBS 749), and T. delbrueckii (D10)) on the fermentation process, basic parameters and odour-active compounds of the produced beers. The chemical composition and key aroma components of the obtained beers were determined using various chromatographic methods (HPLC, GC-FID, GC-MS, and GC-O). We showed large differences between the key aroma components depending on the culture of microorganisms used. Forty different compounds that have an active impact on the creation of the aroma of beers were detected, among which the most important are: β-phenylethanol, ethyl hexanoate, ethyl 4-methylpentanoate, ethyl dihydrocinnamate and β-damascenone. We also found the presence of components specific to the yeast strain used, such as 2-methoxy-4-vinylphenol, γ-decalactone, methional, nerolidol and others. Among the analyzed yeasts, S. kudriavzevii and W. anomalus should be distinguished, which produced beers with intense fruity and floral aromas and were also characterized by favorable features for brewing. The Z. bailii strain also turned out to be interesting as a potential starter culture for the production of low-alcohol beers, significantly differing in sensory characteristics from the standard ones.

LiMYB108 is involved in floral monoterpene biosynthesis induced by light intensity in Lilium 'Siberia'.

We find that the MYB family transcription factor, LiMYB108, has a novel function to regulate the floral fragrance affected by light intensity. Floral fragrance determines the commercial value of flowers and is influenced by many environmental factors, especially light intensity. However, the mechanism by which light intensity affects the release of floral fragrance is unclear. Here, we isolated an R2R3-type MYB transcription factor LiMYB108, the expression of which was induced by light intensity and located in the nucleus. Light of 200 and 600μmolm-1s-1 significantly increased the expression of LiMYB108, which was consistent with the improving trend of monoterpene synthesis under light. Virus-induced gene silencing (VIGS) of LiMYB108 in Lilium not only significantly inhibited the synthesis of ocimene and linalool, but also decreased the expression of LoTPS1; however, transient overexpression of LiMYB108 exerted opposite effects. Furthermore, yeast one-hybrid assays, dual-luciferase assays, and electrophoretic mobility shift assays (EMSA) demonstrated that LiMYB108 directly activated the expression of LoTPS1 by binding to the MYB binding site (MBS) (CAGTTG). Our findings demonstrate that light intensity triggered the high expression of LiMYB108, and then LiMYB108 as a transcription factor to activate the expression of LoTPS1, thus promoting the synthesis of the ocimene and linalool, which are important components of floral fragrance. These results provide new insights into the effects of light intensity on floral fragrance synthesis.

Effects of Different Brewing Technologies on Polyphenols and Aroma Components of Black Chokeberry Wine

The black chokeberry is a shrub of the Rosaceae family, which is characterized by strong acidity and astringency and is widely processed into wine and alcoholic beverages. However, due to the characteristics of black chokeberries, the wine brewed by traditional methods often has a strong sour taste, weak aroma, and poor sensory quality. In order to improve the sensory quality and explore the effects of different brewing technologies on polyphenols of black chokeberry wine, five brewing technologies (traditional fermentation, frozen fruit fermentation, co-fermentation, carbonic maceration, and co-carbonic maceration) were used in this study. The results showed that compared with the traditional method, the four alternative brewing technologies could reduce acidity, increase the contents of several major polyphenols, and enrich floral scents and fruity aroma, thus significantly improving the sensory qualities of black chokeberry wine. The proposed brewing technologies would be applied to the production of quality black chokeberry or other fruit wines.

Comparative Study on Effectiveness of Organic Pineapple Juice Vinegar Over Commercially Available Vinegar Using Chemical Titration Technique for Chicken Quality Analysis

Aim: The production of innovative Pineapple vinegar necessitates the use of a low-cost raw material due to the commodity’s low price.The present investigation represents the use of pineapple waste as a new substrate. Materials and Methods: In this method, the juice and core of the pineapple (Ananas comosus) can be used instead of being thrown away during processing or consumption. For 6-8 days at 25°C, the waste was fermented with Saccharomyces cerevisiae and a combination of physical and enzymatic treatments to turn it into a sugar. Two groups are taken with 8 sample size per group, G power 80%, coincidence interval will be 95%. Results: Acitric fermentation with Acetobacter aceti and the alcoholic medium took about 15 days at 30°C, and the final product had an acidity of 7.8%. Chemical titration was used to determine the amount of volatile and fixed compounds in the acetified samples, and the results showed that the concentration of acetic acid in the pineapple vinegar was significantly more than in the original wine (p=0.001). Conclusion: The metabolite profile of pineapple waste vinegar, which has a slight floral aroma, has never been studied before. It has also been shown that reusing pineapple fruits in food products with added nutritional value can significantly reduce post-harvest losses. The final pineapple vinegar had a stronger aroma due to the presence of more alcohols, aldehydes, and ketones, while the off-flavors were significantly reduced compared to the original.

Volatilomics Analysis of Jasmine Tea during Multiple Rounds of Scenting Processes

Jasmine tea is reprocessed from finished tea by absorbing the floral aroma of jasmine (Jasminum sambac (L.) Aiton); this process is commonly known as "scenting". Making high-quality jasmine tea with a refreshing aroma requires repeated scenting. To date, the detailed volatile organic compounds (VOCs) and the formation of a refreshing aroma as the number of scenting processes increases are largely unknown and therefore need further study. To this end, integrated sensory evaluation, widely targeted volatilomics analysis, multivariate statistical analyses, and odor activity value (OAV) analysis were performed. The results showed that the aroma freshness, concentration, purity, and persistence of jasmine tea gradually intensifies as the number of scenting processes increases, and the last round of scenting process without drying plays a significant role in improving the refreshing aroma. A total of 887 VOCs was detected in jasmine tea samples, and their types and contents increased with the number of scenting processes. In addition, eight VOCs, including ethyl (methylthio)acetate, (Z)-3-hexen-1-ol acetate, (E)-2-hexenal, 2-nonenal, (Z)-3-hexen-1-ol, (6Z)-nonen-1-ol, β-ionone, and benzyl acetate, were identified as key odorants responsible for the refreshing aroma of jasmine tea. This detailed information can expand our understanding of the formation of a refreshing aroma of jasmine tea.

Screening of the Volatile Composition and Olfactory Properties of Aglianico and Primitivo, Two Southern Italian Red Wines

Gas-chromatography/mass-spectrometry and sensory descriptive analyses were applied to provide new data on volatile and olfactory properties of Aglianico and Primitivo (Zinfandel), Italian red wines of growing interest. The relationships between data sets were investigated by multivariate statistical analyses: Principal Component and Hierarchical Clustering Analyses (PCA, HCA). A total of 35% of the volatiles varied significantly (ANOVA) between the two wines, mostly showing higher amounts in the Aglianico samples. Multivariate analyses showed intra-varietal similarity and inter-varietal diversity in terms of aromatic characteristics. PCA indicated that Aglianico wines were mainly related to the main fermentative alcohols, with a sensory impact, and to terpenols, suggesting a potential discriminating power at a compositional level. Primitivo wines formed two groups, one of which correlated to the floral aroma vector linked to beta-phenethyl acetate and beta-ionone. These findings may be valuable for updating the information on these wines and for future research to improve and obtain more targeted production and communication approaches.

Volatile Constituents from Catasetum (Orchidaceae) Species with Occurrence in the Brazilian Amazon.

Catasetum Rich. ex Kunth is a genus of Neotropical orchids distributed in Central and South American regions. In the Brazilian Amazon, there are more than 60 species of Catasetum. The floral aromas of orchids are little known, particularly of Catasetum species. This work aimed to analyze the chemical constituents of the volatile concentrates of eight Catasetum specimens from the Amazon: C. alatum (1), C. albovirens (2), C. barbatum (1), C. ciliatum (2), C. galeritum (1), and C. gnomus (1). Gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) analyzed and identified the constituents of the volatile concentrates, and principal component analysis (PCA) and hierarchical cluster analysis (HCA) were used in the multivariate statistical analysis. The Catasetum main constituents in descending order and above 10% were trans-geranylgeraniol, 1,4-dimethoxybenzene, linalool, 2-phenylethyl acetate, geraniol, 7-epi-1,2-dehydro-sesquicineole, 1,8-cineole, benzyl acetate, limonene, methyl salicylate, (E)-β-farnesene, anisyl butyrate, cis-carvone oxide, cadin-4-en-10-ol, indole, α-pinene, and δ-cadinene. Multivariate statistical analysis of Catasetum species showed that C. barbatum, C. albovirens, and C. gnomus are distinct from the other studied species, while C. alatum, C. ciliatum, and C. galeritum presented the same primary classes of compounds. These results contribute to a better understanding of the genus Catasetum chemotaxonomy.

Visible light-based polymerization of poly (methyl methacrylate) encapsulated fragrances used for fabric softener applications

A visible-light-based photopolymerization is an attractive approach for encapsulating volatile essential oils with low aqueous solubility and stability. This research aimed to encapsulate pink fruity fragrance (PF) and white floral fragrance (WF) with poly (methyl methacrylate) (PMMA), termed respectively as PF-PMMA and WF-PMMA, through photopolymerization under blue-light emitting diodes (LEDs) exposure. The PF-PMMA and WF-PMMA were used in fabric softeners to provide a long-lasting fragrance to the fabric. The wavelength of the blue-LEDs light was 410–530 nm, while camphorquinone and ethyl 4-(dimethylamino) benzoate were used as co-photoinitiators. The effect of the mixing ratio between polymer shell and core material on particle size, conversion, and encapsulation efficiency of WF-PMMA and PF-PMMA was investigated. The size of the prepared WF-PMMA and PF-PMMA microcapsules were 3.1–3.7 µm and 2.1–2.3 µm, respectively. These microcapsules were added to fabric softeners and applied to TC fabric. The highest encapsulation efficiency and conversion of WF-PMMA and PF-PMMA were 95.7 ± 0.1 %, 93.5 ± 2.4 %, 89.4 ± 1.0 %, and 74.1 ± 4.2 %, respectively. It was also found that the fragrances remaining in the fabrics after 30 d storage was 54.3 % for PF-PMMA and 37 % for WF-PMMA. The results presented the high potential for microencapsulation of fragrances by photopolymerization to prolong the fragrance release duration.

Quality Improvement in Apple Ciders during Simultaneous Co-Fermentation through Triple Mixed-Cultures of Saccharomyces cerevisiae, Pichia kudriavzevii, and Lactiplantibacillus plantarum.

This study explored the effect of the combination of Saccharomyces yeast, non-Saccharomyces yeast (Pichia kudriavzevii), and Lactiplantibacillus plantarum during cider fermentation on physicochemical properties, antioxidant activities, flavor and aroma compounds, as well as sensory qualities. Ciders fermented with the triple mixed-cultures of these three species showed lower acid and alcohol content than those fermented with the single-culture of S. cerevisiae. The antioxidant activities were enhanced by the triple mixed-culture fermentation, giving a higher 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging rate and total antioxidant capacity; specifically, the SPL5 cider showed the highest DPPH radical scavenging rate (77.28%), while the SPL2 gave the highest total antioxidant capacity (39.57 mmol/L). Additionally, the triple mixed-culture fermentation resulted in improved flavor and aroma with a lower acidity (L-malic acid) and higher aroma compounds (Esters), when compared with the single-culture fermented ciders (Saccharomyces cerevisiae); more specifically, the SPL4 cider resulted in the highest total flavor and aroma compounds. In addition, sensory evaluation demonstrated that ciders produced using the triple mixed-cultures gained higher scores than those fermented using the single-culture of S. cerevisiae, giving better floral aroma, fruity flavor, and overall acceptability. Therefore, our results indicated that the triple mixed-cultures (S. cerevisiae, P. kudriavzevii, and L. plantarum) were found to make up some enological shortages of the single S. cerevisiae fermented cider. This study is believed to provide a potential strategy to enhance cider quality and further give a reference for new industrial development protocols for cider fermentation that have better sensory qualities with higher antioxidant properties.

Review of the chemical ecology of homoterpenes in arthropod–plant interactions

AbstractThe homoterpenes 4,8‐dimethyl‐1,3,7‐nonatriene (DMNT) and 4,8,12‐trimethyl‐1,3,7,11‐tridecatetraene (TMTT) are volatile products of plant metabolism reported from diverse plant taxa and multiple plant tissues. As such, they have a range of potential ecological functions. Here, we review the key literature to assess evidence for roles in contrasting plant–arthropod interactions. TMTT, and DMNT especially, have been reported as sometimes dominant constituents of floral scents from angiosperm taxa ranging from primitive Magnoliales to more advanced, taxonomic orders of economic significance such as Fabales and Sapindales. Although all taxa producing TMTT and DMNT in floral scents are entomophilous (‘insect pollinated’), experimental evidence for an assumed role of these homoterpenes in pollinator attraction is limited. Representing a trade‐off, in some cases, homoterpenes in floral scents have been shown to act as kairomones, attracting herbivores. Additionally, both TMTT and DMNT are released by plant foliage in response to arthropod feeding, mechanical damage simulating feeding, or even egg deposition. Evidence for a functional role in herbivore‐induced plant volatile (HIPV) blends comes from a wide range of angiosperm orders, including anemophilous (‘wind pollinated’) taxa, as well as from gymnosperms. We conclude by considering how TMTT and DMNT function in community‐level interactions and highlighting research priorities that will reveal how plants avoid trade‐offs from contrasting ecological functions of DMNT and TMTT release and how homoterpene production might be exploited to develop improved crop varieties.

Effect of different salt substitutions on the decomposition of lipids and volatile flavor compounds in restructured duck ham

Excessive salt intake can increase the risk of cardiovascular diseases such as hypertension. Effect of different methods of salt substitution on lipid oxidation and volatile compounds formation by fermented restructured hams was studied. Sensory ratings of 30% KCl+70% NaCl (w/w) and 25% k-lactate+75% NaCl (w/w) showed higher odor scores than 100% NaCl. HS-SPME-GC-MS results indicated that nonanal (fatty), 2-decenal, 2-methyl-butanoic acid methyl ester, 2-pentyl-furan (fruity), benzeneacetaldehyde (flora rose & sweet), linalool (floral aroma), linalyl acetate, eugenol, and 1-octen-3-ol (mushroom aroma) were the main contributors to this discrepancy. Furthermore, these compounds were mainly related to the degradation of lipids. The increase in the activity of critical enzymes affecting lipid degradation, such as acidic and neutral lipase, LOX, further led to an increase in fatty acid content in the salt substitution group. Correlation analysis demonstrated that unsaturated fatty acids such as C20:4n6, C20:6n3, and C18:2n6c were the main precursors to specific flavors of salt substitution. Therefore, this study has a guiding significance for producing healthy, low-salt, restructured ham with excellent organoleptic acceptability.

Comparative Study of the Effect of Temperature and pH on the Growth of Bio-flavor Producing Microorganisms Kluyveromyces marxianus and Ceratocystis fimbriata

Kluyveromyces marxianus and Ceratocystis fimbriata are two potential microorganisms that have been reported to produce fruity and floral aroma compounds during fermentation. In the present investigation, an in vitro comparative study was conducted using a liquid medium to investigate the effect of temperature from 20±2°C to 45±2°C and pH from 3 to 8 on the growth of both microorganisms. The results showed that the optimum growth of K. marxianus was found at 30°C while C. fimbriata showed the highest growth at 20°C. Similarly, the optimum growth of K. marxianus was found at pH 4.5 while C. fimbriata showed the highest growth at pH 6.5. The comparative analysis suggested that K. marxianus has a shorter lag phase and shows better growth at ambient temperature and pH compared to C. fimbriata. Thus, it is concluded that K. marxianus can be a better choice for the industrial production of bio-flavors.

Floral scent chemistry of sympatric species of Philodendron (Araceae) sharing a common pollinator in the fragmented coastal Atlantic Forest of southeastern Brazil

Floral volatiles are crucial components in flower advertisement, often contributing to the reproductive isolation of angiosperms through scent-mediated differential pollinator attraction. Recently, there were significant advances in our understanding of the chemical communication between plants and cyclocephaline beetles, a predominant group of Neotropical pollinators. However, details on how the floral scent chemistry differs or converges among species pollinated by different or the same cyclocephaline beetle species are still unknown. Here, we used dynamic headspace sampling and gas chromatography coupled with mass spectrometry to investigate the floral fragrance chemistry of eight co-flowering Philodendron (Araceae) species that share a single pollinator, Cyclocephala variolosa (Melolonthidae, Cyclocephalini). Additionally, we compared our results to published data on the floral fragrances of different conspecifics pollinated by other species of cyclocephaline beetles. Although all the investigated Philodendron spp. emitted perceivably intense floral scents, the number of volatile organic compounds in the analyzed samples varied between 1 and 50 among species. Also, the overall relative scent composition strongly differed among species (or chemotypes). The floral scents of four of the investigated species (P. appendiculatum, P. cordatum, P. crassinervium, and P. eximium) and one of the two chemotypes of P. corcovadense were dominated by (Z)-jasmone (46 to 100% total relative concentration). High relative amounts of (Z)-2-pentenyl acetate (44 to 66%) characterized the samples of P. undulatum and Philodendron bipinnatifidum, while (E)-4,8-dimethyl-1,3,7-nonatriene was the main constituent in samples of P. curvilobium (75%) and the other P. corcovadense chemotype (56%). The scents of Philodendron spp. pollinated by C. variolosa differed from those of conspecifics associated with other cyclocephaline beetle species, but we also verified significant interspecific variation among these species sharing a common pollinator. We hypothesize that this community of co-flowering plants might be reproductively isolated despite being pollinated by the same pollinator species and having partly overlapping scent compositions.

Volatile metabolome and floral transcriptome analyses reveal the volatile components of strongly fragrant progeny of Malus × robusta.

Floral fragrance is an important trait that contributes to the ornamental properties and pollination of crabapple. However, research on the physiological and molecular biology of the floral volatile compounds of crabapple is rarely reported. In this study, metabolomic and transcriptomic analyses of the floral volatile compounds of standard Malus robusta flowers (Mr), and progeny with strongly and weakly fragrant flowers (SF and WF, respectively), were conducted. Fifty-six floral volatile compounds were detected in the plant materials, mainly comprising phenylpropane/benzene ring-type compounds, fatty acid derivatives, and terpene compounds. The volatile contents were significantly increased before the early flowering stage (ES), and the contents of SF flowers were twice those of WF and Mr flowers. Odor activity values were determined for known fragrant volatiles and 10-11 key fragrant volatiles were identified at the ES. The predominant fragrant volatiles were methyl benzoate, linalool, leaf acetate, and methyl anthranilate. In the petals, stamens, pistil, and calyx of SF flowers, 26 volatiles were detected at the ES, among which phenylpropane/benzene ring-type compounds were the main components accounting for more than 75% of the total volatile content. Functional analysis of transcriptome data revealed that the phenylpropanoid biosynthesis pathway was significantly enriched in SF flowers. By conducting combined analyses between volatiles and differentially expressed genes, transcripts of six floral scent-related genes were identified and were associated with the contents of the key fragrant volatiles, and other 23 genes were potentially correlated with the key volatile compounds. The results reveal possible mechanisms for the emission of strong fragrance by SF flowers, and provide a foundation for improvement of the floral fragrance and development of new crabapple cultivars.

Pollination biology of Aristolochia bianorii Sennen & Pau: promoting cross-pollination but assuring reproductive success in island ecosystems.

Deceptive pollination has been reported in the genus Aristolochia, but the floral biology and pollination strategy of A. bianorii, an endemic of the Balearic Islands, have not yet been studied. Here, we investigated floral anthesis, mating system, pollinators and volatile organic compounds (VOCs) emitted by its flowers. Flower buds were marked and monitored daily to define floral stages and their duration. Experimental bagging and hand-pollination were performed to test for autonomous self-pollination, induced self-pollination and cross-pollination. Flowers were collected to analyse the presence of entrapped pollinators. VOCs emitted by flowers were evaluated by means of solid phase microextraction followed by immediate GC-MS. Anthesis lasted between 63 and 96 h, and the species exhibited autonomous self-pollination with moderate inbreeding depression. Pollinators were mainly females of Oscinomorpha longirostris (Diptera; Chloropidae). The number of pollinators inside flowers was affected by floral stage and time of flowering. The most common VOCs were alkanes, oximes, esters, alkenes, cyclic unsaturated hydrocarbons, isocyanates, amides and carboxylic acids. Aristolochia bianorii can set seed by autonomous self-pollination, in contrast to other Aristolochia species, in which both protogyny and herkogamy prevent autonomous self-pollination. However, the species may encourage cross-pollination by attracting female chloropid flies though emission of floral scents that may mimic an oviposition site and, possibly, freshly killed true bugs (i.e. Heteroptera). In conclusion, A. bianorii promotes cross-pollination, but delayed autonomous self-pollination assures reproductive success in the putative absence of pollinators.

Effect of microencapsulated inoculum of Pichia kudriavzevii on the fermentation and sensory quality of cacao CCN51 genotype.

Microencapsulated yeasts are a novel alternative as a delivery matrix for microbiological starters. This technology aims to protect the active compounds from adverse environmental conditions and prolong their useful life and could also improve the conditions of the starters for cocoa fermentation. The present study established the effective dose to apply the microencapsulated yeast Pichia kudriavzevii as a microbiological starter of fermentation and biotechnological strategy for promoting the biochemical dynamics and sensory expression of the cocoa variety CCN-51. For this, 0.5%, 1%, 2%, and 3% of microencapsulated P. kudriavzevii yeast insolated from the artisanal fermentation process of cocoa was added to the cocoa mass to be fermented and studied on a laboratory scale. The partial least squares regression of fermentation was related in four quartiles, comprising the hedonic judgments of the sensory evaluation with the biochemical traits of the cocoa liquor, finding a high correlation between the physicochemical variables total phenols, percentage of insufficiently fermented grains, and percentage of total acidity, with a level of bitterness and defects found in liquors with the addition of 0.5% of microencapsulated starter. The treatments with the addition of 2% and 3% of the inoculum showed a high correlation between the variables pH, total anthocyanins, cocoa, fruity and floral aromas, sweet taste, and general aroma perception. The higher presence of volatile compounds such as 2,3-butanediol associated with cocoa aroma and 1-phenyl-2-ethanol and acetophenone associated with aromatic descriptors of fruity and floral series allowed establishment in 2% of microencapsulated P. kudriavzevii yeast, comprising the effective dose for promoting the biochemical dynamics of laboratory-scale fermentation and the development of cocoa, as well as the fruity and floral aromas of cocoa CCN-51 liquor. The microencapsulation is suitable for cocoa starters. © 2023 Society of Chemical Industry.