Differences In Volatile Profiles Research Articles

Differences in Volatile Profiles and Sensory Characteristics in Plum Spirits on a Production Scale

The specific sensory properties attributed to distillates from different plum varieties are intricately linked to aromatic substances, fruit quality, and technology employed during production. This study compares four plum brandies, each made from a renowned plum variety: Presenta, Valjevka, Čačanská lepotica, and Čačanská rodná on a production scale. Analytical and sensory profiles were assessed using GC-FID, an available analytical method advantageous for monitoring industrial fruit distillate production. Between 71 and 85 analytes were detected in the distillates, with the Presenta plum distillate containing the highest number of substances. Statistically significant differences in analyte concentration between plum varieties (p < 0.05) were observed for 11 analytes. The comparison of analytical profiles and sensory evaluation revealed that a high concentration of 1-propanol, despite its negative sensory perception, significantly impacts the overall perception of a distillate, contrasting with substances like acetaldehyde and propyl acetate, which have positive sensory evaluations but lesser significance in content. Our work identified key compounds and procedures that can be used as benchmarks for production of plum brandy with positive sensory evaluation. These findings demonstrate the broad application potential of GC-FID in fruit distillate production as an independent tool for aromatic profile assessment and quality control.

Mango headspace volatiles trigger differential responses of the mango fruit fly Ceratitis cosyra and its parasitoids

Before the introduction of Bactrocera dorsalis (Hendel) to sub-Saharan Africa, Ceratitis cosyra (Walker) was economically the most important pest in mango farming. Its native natural enemy, the solitary parasitoid Psyttalia cosyrae (Wilkinson), played a crucial role in C. cosyra bio-control, later complemented by the exotic parasitoids Diachasmimorpha longicaudata (Ashmead) and Fopius arisanus (Sonan) among Integrated Pest Management (IPM) systems. To understand the in situ mango-C. cosyra-parasitoid tritrophic interaction, we assessed the responses of the fruit fly and the three parasitoids to headspace volatiles from various mango conditions. These conditions included non-infested mature unripe mangoes, C. cosyra-infested mangoes, 7th- and 9th-day post-infestation mangoes, non-infested ripe mangoes of three varieties (Kent, Apple, and Haden), and clean air (blank). We also compared the fruit fly's performance in the mango varieties and identified the chemical profiles of mango headspace volatiles. Ceratitis cosyra was attracted to both infested and non-infested mangoes (66–84 % of responsive C. cosyra) and showed superior performance in Kent mango (72.1 % of the 287 puparia recovered) compared to Apple and Haden varieties. Fopius arisanus displayed a stronger attraction to the volatiles of C. cosyra-infested mangoes (68–70 %), while P. cosyrae and D. longicaudata were significantly attracted to the 9th-day post-infestation mangoes (68–78 %) compared to non-infested mango volatiles. Gas chromatography-mass spectroscopy showed substantial quantitative and qualitative differences in volatile profiles among mango treatments. Esters predominated in non-infested ripe, 7th- and 9th-day post-infestation mangoes, while monoterpenes and sesquiterpenes were most dominant in the other treatments. The in situ experiments underscored varying preferences of the species for mango headspace volatiles and their subsequent treatments. These results provide valuable insights for further exploration, specifically in identifying the key volatiles responsible for species responses, to facilitate the development of applicable selective semiochemicals for managing species of African fruit fly.

Host Volatiles Potentially Drive Two Evolutionarily Related Weevils to Select Different Grains.

The Sitophilus zeamais (maize weevil) and Sitophilus oryzae (rice weevil) are two insect pests that have caused huge economic losses to stored grains worldwide. It is urgent to develop an environmentally friendly strategy for the control of these destructive pests. Here, the olfactory-mediated selection preference of the two weevil species to three stored grains was analyzed, which should help establish a pull-push system in managing them. Bioassays showed that maize weevil adults prefer to select maize, followed by paddy and wheat, while rice weevil adults mainly migrate towards wheat. Volatile analyses revealed that 2-ethylhexanol, piperitone, and (+)-Δ-cadiene are the major components in volatiles from both maize and wheat, but the abundance of these chemicals is much lower in maize than that in wheat. The volatile limonene was only detected in paddy. Y-tube bioassays suggest that 2-ethylhexanol, piperitone, and (+)-Δ-cadiene were all attractive to both weevils, whereas limonene was attractive only to rice weevils. Overall, maize weevil appeared more sensitive to the tested volatiles based on having much lower effective concentrations of these volatiles needed to attract them. The differences in volatile profiles among the grains and the sensitivity of the two species towards these volatiles may explain the behavioral differences between maize and rice weevils in selecting host grains. The differences in sensitivity of maize and rice weevils towards host volatile components with abundance differences are likely determinants driving the two insect species to migrate towards different host grains.

Rearing and 60Co radiation do not affect attractiveness but alter the volatile profiles released by Anastrepha obliqua calling males.

Calling males of Anastrepha obliqua release volatile compounds to attract conspecific males to form leks and females to mate. Male volatiles from Mexican and Brazilian populations of A. obliqua have been previously identified. However, there are differences in the number and identity of volatile compounds between the populations. These differences in volatile profiles may be due to male origin (e.g. wild or mass-reared flies) or methodological issues (e.g. sampling techniques). In this study, we evaluated the attractiveness of wild, laboratory non-irradiated, and laboratory-irradiated flies under semi-field conditions. Male volatiles were collected using dynamic headspace sampling (DHS) and solid-phase microextraction (SPME) techniques, and identified using gas chromatography-coupled mass spectrometry. The results showed no difference in the attractiveness of wild, laboratory non-irradiated, and irradiated males to females. However, the number of captured females differed according to the origin; wild and non-irradiated females were captured more frequently than the irradiated flies. A total of 21 compounds were found using SPME, whereas only 12 were collected using DHS, although the relative amounts of these compounds were higher than those obtained using the former sampling technique. In addition, only laboratory non-irradiated males released α-pinene and menthol, which have not been previously reported in this fruit fly species. Additionally, we identified novel compounds in A. obliqua; however, certain compounds previously reported were not detected. This study suggests that despite the qualitative and quantitative variations in the volatile profiles of A. obliqua males, their attractiveness was unaffected.

Comparative genomics and fermentation flavor characterization of five selected lactic acid bacteria provide predictions for flavor biosynthesis metabolic pathways in fermented muskmelon puree

AbstractFive species of plant‐derived lactic acid bacteria (LAB), including Pediococcus pentosaceus, Lactococcus garvieae, Lactiplantibacillus paraplantarum, Weissella paramesenteroides, and Lactococcus lactis, were used for muskmelon fermentation to improve flavor characteristics. Comparative genomic analysis showed that a high proportion of annotated genes were related to carbohydrate metabolism and amino acid metabolism in all five strains. L. lactis P‐1 (Ll1) contained the highest proportion (2.02%) of genes from the glycoside hydrolase family associated with carbohydrate metabolism. Gas chromatography–mass spectrometry results showed that 89 volatile compounds in muskmelon purees were identified; the largest number of volatile compounds was detected in fermented muskmelon puree (FMP) inoculated with W. paramesenteroides FL3, followed by L. paraplantarum FL‐8. A total of 25 key volatile compounds were screened in muskmelon puree, and some unique key volatile compounds (e.g., β‐damascenone, phenylacetaldehyde, and 3‐penten‐2‐one) and taste compounds (e.g., mannitol) were produced by different LAB strains. L. garvieae Pa‐2 and Ll1 were considered to have greater potential due to their ability to produce a greater category of pleasant key aromas. Based on the correlations of potential pathways analyzed using comparative genomics and detected flavor profiles, flavor synthesis pathways in FMP were predicted. Some carbohydrate, amino acid, and fatty acid metabolism pathways, including tricarboxylic acid cycle, glycolysis, and cysteine and methionine metabolism pathways, are common to all five LAB strains. Furthermore, differences in the predicted flavor biosynthesis metabolic pathways in monoterpenoid biosynthesis, phenylalanine metabolism, fatty acid biosynthesis, and fructose and mannose metabolism pathways explained the differences in volatile profiles produced by different strains.

Chemical cues involved in the host foraging behavior of Psyttalia concolor wasps to locate the olive fruit fly Bactrocera oleae

Foraging parasitoids rely on infochemicals, derived from the habitat, host plant and/or host insect itself. Here, we studied the olive fruit fly Bactrocera oleae (Rossi) (Diptera: Tephritidae), a major pest in olive agroecosystem and its larval parasitoid, Psyttalia concolor (Szépligeti) (Hymenoptera: Braconidae), a well-established and abundant wasp in Crete. To improve parasitoid’s efficiency as biological control agent, more knowledge on its host location behavior is required. The aim of this study was to investigate the role of oviposition- (OIPVs) and herbivore-induced plant volatiles (HIPVs) emitted by olive trees upon infestation by B. oleae as well as cues emitted by B. oleae, e.g., pheromones, therein. We conducted two-choice bioassays to test the preference of P. concolor to different olfactory stimuli. Moreover, we collected headspace volatiles from olive fruits and branches to investigate whether egg or larval infestation changes volatile emissions locally or/and systemically. We found that P. concolor wasps showed a strong preference to volatiles of B. oleae larval-infested fruits (HIPVs) compared to clean air, non-infested, egg-infested, and mechanical-damaged fruits. But they were not able to discriminate between volatiles of non-infested and larval-infested branches. In addition, the wasps were attracted to cues emitted from the virgin and mated B. oleae females. They were neither attracted to cues emitted by the virgin and mated males nor to the olive fruits with or without the cues of the oviposition marking of the B. oleae. We found important qualitative differences in volatile profiles of egg- and larval-infested fruits: nineteen volatile compounds were only detected in infested fruits, such as the terpenoids (E)-β-ocimene and (E,E)-α-farnesene. Moreover, volatile analysis showed that olives change volatile emissions locally and systemically in response to larval infestation. Our results suggest that both HIPVs and host cues play an important role to P. concolor during host location. Further knowledge on the chemical compounds utilized by the parasitoid to locate infested fruits could help application in olive orchards and to improve the control of the olive fruit fly by natural enemies.

Attraction of the Air Potato Leaf Beetle, Lilioceris Cheni, (Coleoptera: Chrysomelidae) to leaf Volatiles of the Air Potato, Dioscorea bulbifera.

Air potato, Dioscorea bulbifera L., is an invasive vine found in the southeastern United States and is native to Asia and Africa. The air potato leaf beetle Lilioceris cheni (Coleoptera: Chrysomelidae), is a host specific biological control agent introduced for D. bulbifera control. In this study, odor cues that control the attraction of L. cheni to D. bulbifera were investigated. The first experiment investigated the response of L. cheni to D. bulbifera leaves versus no leaves in the presence or absence of air flow. The experiment showed a significant response of L. cheni to D. bulbifera leaves in the presence of air flow with leaves placed upwind. When air flow and/or leaves were absent, L. cheni dispersed randomly between the upwind and downwind targets, indicating L. cheni uses volatiles from D. bulbifera in host selection. The second experiment investigated L. cheni response to undamaged, larval-damaged, and adult-damaged plants. Lilioceris cheni showed preference to move towards conspecific damaged plants compared to undamaged plants but did not discriminate between larvae-damaged or adult-damaged plants. The third experiment investigated volatile profiles of damaged D. bulbifera plants using gas chromatography coupled with mass spectroscopy. We found significant differences in volatile profiles between adult and larval damaged plants compared to mechanically damaged and undamaged plants, with increases in 11 volatile compounds. However, larval and adult-damaged volatile profiles did not differ. The information acquired during this study could be used to develop strategies to monitor for L. cheni and improve its biological control program.

The volatile profile of pasteurized leek (Allium ampeloprasum var. porrum) and Brussels sprouts (Brassica oleracea var. gemmifera) (products), as a witness to (bio)chemical reactivity, influenced by pretreatment and successive refrigerated storage

Processing can affect (bio)chemical conversions in vegetables and can act on their volatile properties accordingly. In this study, the integrated effect of pretreatment and pasteurization on the volatile profile of leek and Brussels sprouts and the change of this profile upon refrigerated storage were investigated. Pretreatments were specifically selected to steer biochemical reactivities to different extents. Volatile profiles were analyzed by headspace-solid phase microextraction-gas chromatography-mass spectrometry. For both vegetables, it was observed that different pretreatments prior to a pasteurization step led to diverse volatile profiles. The differences in volatile profiles observed in the different samples were presumably attributed to the different degrees of enzymatic conversions, further conversions of enzymatically formed products and thermally induced reactivities. Interestingly, the observed initial relative differences between volatile profiles of differently pretreated pasteurized samples were still observed after a refrigerated storage of 4 weeks at 4 °C. In conclusion, refrigerated storage only limitedly affected the resulting volatile profile.

Study of volatile compounds in Greek pistachio (Pistacia vera L. ‘Aegina’ cultivar) oils using Soxhlet and ultrasound assisted extraction

Headspace solid-phase microextraction followed by gas chromatography-mass spectrometry (HS-SPME/GC-MS) represents the most used solvent-free methodology for the characterization of the complex and heterogeneous mix of volatile compounds. The present study investigates the differences in volatile profile of pistachio oils ‘Aegina’ cultivar extracted with two different techniques, ultrasound assisted extraction (UAE) and Soxhlet. Differences were observed both in the pistachio oil yield and the composition of the volatile compounds among these two groups of samples, which were significantly influenced due to the different thermal conditions. In terms of pistachio oil yield, the Soxhlet extraction technique was proven more efficient (52.5–68.2% w/w) than the UAE type (28.2–42.6% w/w). A total of 34 and 30 volatile compounds were identified for UAE and Soxhlet, respectively. The main ones associated with UAE were α-pinene, octane and decane, while the volatiles formed as a consequence of Soxhlet extraction were decane, nonanal and (E)-2-decenal. Terpenes' concentrations were found decreased in Soxhlet's samples, but hydrocarbons and aldehydes were significantly increased in these samples. Numerous studies concluded in common results. However, this article is the first to explore the influence of different extraction types on the volatile profile of the unique flavour and odor pistachio oil ‘Aegina’ cultivar.

Evaluation by a GC Electronic Nose of the Differences in Volatile Profile Induced by Stopping Fermentation with Octanoic and Decanoic Acid to Produce Sweet Wines

Due to their inhibitory effect on the growth and fermentation of yeasts, medium-chain fatty acids can be used for the production of naturally sweet wines. Addition of octanoic acid, decanoic acid or their combinations is able to stop the alcoholic fermentation, reducing at the same time the doses of sulphur dioxide addition needed for the same goal in the classical technologies. Doses in the range of 10–30 mg L−1 of these acids were used, and their effect on the aroma profile of the sweet wines obtained was evaluated by using a chromatographic electronic nose with two columns. Based on the chromatographic peaks, which are considered the sensors of this e-nose, differentiation of the wines treated with octanoic or decanoic acids is easily achieved. The acid doses, the type of acid and also the yeast used for fermentations have all detectable influences on the volatile profiles of the wines. Discriminant factor analysis was applied on the e-nose data to separate the wines obtained with different treatments. Several differences in the content of the volatile compounds were identified and discussed in view of their sensory influences and the impact of treatment and yeast, respectively. Special attention was given to the formation of ethyl octanoate and ethyl decanoate which, at acid additions over 10 mg L−1, are formed in quantities which have a detectable influence on the aromatic profile. Ethyl octanoate and decanoate are produced in direct relation to the dose of the corresponding acids, but the yeast named ST leads to higher amounts of ethyl decanoate while the one named ERSA leads to higher amounts of ethyl octanoate. In accordance with the e-nose results, the aromatic profile obtained by stopping the fermentation with decanoic acid and using the ERSA yeast is more complex, the wines thus produced preserving more of the varietal and fermentation aroma. This research will be continued at an industrial scale.

Inoculation of Latilactobacillus sakei with Pichia kluyveri or Saccharomyces boulardii improves flavor compound profiles of salt-free fermented wheat-gluten: Effects from single strain inoculation

Wheat-gluten, the protein-rich portion of wheat, can be processed to produce a highly savory sauce product after solid and liquid-state fermentation (SSF and LSF) with the inoculation of selected lactic acid bacteria (LAB) and yeast under salt-free condition. However, limited research has been done on the impact of different types of microbes in this process. This work studied the flavour impact on fermented wheat-gluten by the single inoculation of Latilactobacillus sakei or one yeast (Saccharomyces boulardii or Pichia kluyveri). Glucose was depleted during LSF in all treatments. Lactic acid production increased over time in L. sakei-fermented samples but not in yeast-fermented samples. Cysteine, serine and arginine remained low over LSF in L. sakei-fermented samples but increased in yeast-fermented samples. More fruity esters such as isoamyl acetate and isobutyl acetate were detected in samples fermented by P. kluyveri, while S. boulardii boosted the production of alcohols such as 3-methyl butanol and 2-phenylethyl alcohol. Principal component analysis revealed a clear difference in volatile profiles of the samples fermented with different strains. Therefore, the fermented sauce can potentially be processed into different flavor directions, and based on the flavor profile, be used in different food applications.

The Effect of Cow Breed and Wild Garlic Leaves (Allium ursinum L.) on the Sensory Quality, Volatile Compounds, and Physical Properties of Unripened Soft Rennet-Curd Cheese.

The aim of this study was to investigate the effects of cow breed and the addition of wild garlic on the sensory quality, volatile compounds, and physical properties of soft rennet-curd cheese. Cheese was produced from the milk of the Polish Holstein-Friesian breed Black-and-White type and the Polish Red breed, with or without the addition of wild garlic leaves. The samples were analyzed for their sensory quality, volatile compounds (using an electronic nose and GC/MS), color, and texture. The intensity of taste and smell characteristics depended only on the addition of wild garlic. PCA showed that the differences in volatile profiles resulted both from the milk cow breed and the use of wild garlic. Breed influenced almost all color parameters, while the addition of wild garlic affected all of them. The milk source, wild garlic addition, and storage duration influenced the majority of the textural parameters of the cheeses. The research conducted indicates that the addition of wild garlic leaves results in the enrichment of the volatile compound profile of cheese, making its taste and smell less milky and sour (p ≤ 0.001), while modifying its color and some textural properties (p ≤ 0.001); while, at the same time, not adversely affecting the sensory assessment of the color, appearance, texture, smell, or taste of the cheese (p > 0.05).

Plant Volatiles and Herbivore Induced Plant Volatiles from Chili Pepper Act as Attractant of the Aphid Parasitoid Aphelinus varipes (Hymenoptera: Aphelinidae).

Plants have evolved a number of different chemical defenses, covering nearly all classes of (secondary) metabolites, that represent a major barrier to herbivory: some are constitutive; others are induced after attacks from herbivores (HIPVs) and may elicit the attraction of predators and parasitoids. Here, we studied how the female solitary endoparasitoid Aphelinus varipes responds to plant and host aphid volatiles in a series of experiments on five commercially important vegetables that were either healthy or infested with the aphid Myzus persicae: chili pepper, eggplant, crown daisy, Chinese cabbage and cabbage. The results for the olfactory responses of A. varipes showed that the presence of M. persicae increased the attraction of the endoparasitoid to the infested plants. In a second experiment, volatiles from highly attractive and repellent plants were obtained via headspace collection to investigate volatiles from healthy and aphid-damaged plants. The results for the differences in volatile profiles in response to aphid infestation in chili pepper cultivar were dominated by the volatile blends, including α-pinene, decanal and phthalic acid, while in cabbage they were dominated by isophorone. Moreover, when HIPVs with different concentrations were compared, α-pinene at a dose rate of 100 ng/μL attracted more parasitoids, and the comparison was useful to understand the mechanisms of plant secondary volatiles during aphid infestation and to provide new resources to control this insect pest. Overall our study shows how HIPVs can bolster tritrophic interactions by enhancing the attractiveness of parasitoids.

Adult House Fly (Diptera: Muscidae) Response to Black Soldier Fly (Diptera: Stratiomyidae) Associated Substrates and Potential Volatile Organic Compounds Identification

Black soldier fly, Hermetia illucens (L.) (Diptera: Stratiomyidae), larvae are suspected to inhibit house flies, Musca domestica (L.) (Diptera: Muscidae), seeking oviposition sites. However, the mechanisms regulating these interactions are not well known. In this study, a Y-tube olfactometer was used to determine whether black soldier fly eggs, larvae, puparia (without pupae inside), adult carcasses, or resulting frass of black soldier fly decrease attractiveness of adult house flies to an oviposition substrate (i.e., sugar and wheat bran diet, used as the control). Secondly, two symbiotic bacteria associated were isolated, identified, and tested for house fly attractiveness with a Y-tube olfactometer. Thirdly, volatile organic compounds produced by swine feed before and after black soldier fly, or house fly larval digestion were analyzed with gas chromatography-mass spectrometry (GC-MS). Results indicate feed mixed with black soldier fly larval frass, and symbiotic bacteria, Paenalcaligenes sp. associated with black soldier fly, were less attractive to house flies than the control. However, another symbiotic bacterium Lysinibacillus sp. associated with black soldier fly pupae was attractive. In total, 52 volatile organic compounds were identified from treatments previously described. Quantitative differences in volatile profiles across treatments potentially explain the mechanism regulating house fly substrate choices in the presence, or absence, of black soldier fly larvae.

Olfactory Cues in Infant Feeds: Volatile Profiles of Different Milks Fed to Preterm Infants.

Background: Smell is determined by odor-active volatile compounds that bind to specific olfactory receptors, allowing us to discriminate different smells. Olfactory stimulation may assist with digestion and metabolism of feeds in the neonate by activation of the cephalic phase response of digestion. Infants' physiological responses to the smell of different milks suggest they can distinguish between breastmilk and infant formula. We aimed to describe the profile of volatile compounds in preterm breastmilk and investigate how this differed from that of other preterm infant feeding options including pasteurized donor breastmilk, breastmilk with bovine milk-based fortifier, human milk-based products and various infant formulas.Methods: Forty-seven milk samples (13 different infant formulas and 34 human milk-based samples) were analyzed. Volatile compounds were extracted using Solid Phase Micro Extraction. Identification and relative quantification were carried out by Gas Chromatography with Mass Spectrometry. Principal Component Analysis (PCA) and one-way Analysis of Variance (ANOVA) with Tukey's HSD (parametric data) or Conover's post-hoc test (non-parametric data) were used as appropriate to explore differences in volatile profiles among milk types.Results: In total, 122 compounds were identified. Breastmilk containing bovine milk-based fortifier presented the highest number of compounds (109) and liquid formula the lowest (70). The profile of volatile compounds varied with 51 compounds significantly different (adjusted p < 0.001) among milk types. PCA explained 47% of variability. Compared to preterm breastmilk, the profile of volatile compounds in breastmilk with added bovine milk-based fortifier was marked by presence of fatty acids and their esters, ketones and aldehydes; infant formulas were characterized by alkyls, aldehydes and furans, and human milk-based products presented high concentrations of aromatic hydrocarbons, terpenoids and specific fatty acids.Conclusions: Sensory-active products of fatty acid oxidation are the major contributors to olfactory cues in infant feeds. Analysis of volatile compounds might be useful for monitoring quality of milk and detection of oxidation products and environmental contaminants. Further research is needed to determine whether these different volatile compounds have biological or physiological effects in nutrition of preterm infants.

Discrimination of Floral Scents in &lt;i&gt;Chrysanthemum morifolium&lt;/i&gt; Cultivars using Electronic Nose

The aim of the present study was to investigate the differences in volatile profiles among different Korean chrysanthemum cultivars grown as cut flowers. To optimize a method for sampling and comparing scents, the scents were evaluated by electronic nose (E-nose) at different flowering stages and in different organs and cultivars. The values of maximum resistance changes of metal oxide semiconductor sensors and relative aroma intensity were highest at flowering stage III (full flower stage of ray florets and initial opening disc florets) among different stages and in disc florets among different floral organs of cut chrysanthemums. Among the 12 chrysanthemum cultivars, the highest values for response change and relative aroma intensity were observed in the flowers of the ‘Ilweol’ cultivar. To compare scent patterns among the cultivars, E-nose sensor data was subjected to multivariate statistical analysis. Principal component analysis and discriminant function analysis of the volatile metabolic profile data indicated that chrysanthemum samples were clearly discriminated in a cultivar-dependent manner. These results show that different cultivars are characterized by distinct volatile profiles. Hierarchical cluster analysis showed that the 12 chrysanthemum cultivars were separated into 3 main groups according to the relationship of volatile profiles; however, chrysanthemum cultivars were not clustered according to the flower shape. We propose that these results could be used as the basis on which to improve the breeding of cut chrysanthemums based on volatile characteristics.

Evaluation of Volatilomic Fingerprint from Apple Fruits to Ciders: A Useful Tool to Find Putative Biomarkers for Each Apple Variety.

Aroma is a crucial criterion to assess the quality of apple fruits, juices, and ciders. The aim of this study was to explore similarities and differences in volatile profiles among apple fruits, juices, and ciders from different apple varieties (Festa, Branco, and Domingos) by headspace solid-phase microextraction gas chromatography–mass spectroscopy (HS–SPME/GC–MS). A total of 142 volatile organic compounds (VOCs) were identified, but only 9 were common in all analysed matrices and apple-tested varieties. Esters, alcohols, and aldehydes presented a higher concentration in apple fruits and juices, whereas esters, alcohols, and acids were dominant in ciders. Moreover, there were unique VOCs for each matrix and for each variety, highlighting the importance of the selection of apple varieties as an important factor to obtain good sensory and quality ciders, multiple benefits, and legal protection against the misuse of local products.

Phosphine fumigation – Time dependent changes in the volatile profile of table grapes

Industrial and agricultural goods are fumigated in transport containers in order to control pest infestations and to avoid the transmission of alien species. Phosphine is increasingly used prior to the export as fumigant for table grapes, fruit cultures and dried fruits to control active table grapevine insect pests. Less knowledge exists for fumigants about the desorption time of toxic gases and factors that affect the composition of the fumigated good. Therefore, red and white table grapes (´Thompson seedless´, ´Scarlotta´ and ´Flame seedless´) were chosen to represent the allowed group of phosphine fumigated foods and were treated with a concentration of 2000 vpm phosphine (PH3) at different temperatures. In the present study, sorption and desorption behavior of PH3 by table grapes and possible changes in their VOC (volatile organic compounds) profiles were investigated. The PH3 concentration was monitored before and after the fumigation process and was determined under the maximum residue level 0.005 ppm after 35 days. The adsorbed amount of PH3 was not influenced by fumigation parameters. For analysis of the influences on the volatile profile after fumigation, a headspace solid-phase micro-extraction coupled to gas chromatography mass spectrometry (HS-SPME-GC/MS) was used. Small differences in volatile profiles of fumigated and subsequently outgassed table grapes compared to non-fumigated table grapes could be observed. A slight influence on the aldehyde group directly after fumigation could be perceived by a decrease of hex-2-en-1-ol and 1- hexanol in PH3-treated table grapes. The concentrations of both compounds increase again after completion of the desorption process. On the other hand terpenes are not significantly influenced by the fumigation process. Overall these changes are likely to affect table grape aroma characteristics directly after a treatment with PH3 and it could be demonstrated that phosphine alters the volatile profile of fumigated table grapes qualitatively and quantitatively.

Yeast cells in double layer calcium alginate–chitosan microcapsules for sparkling wine production

This paper focuses on the use of a new type of yeast encapsulation procedure, applying the chitosan-calcium alginate double layer microcapsules, for the production of Riesling sparkling wine. Four different sparkling wines were produced by free or encapsulated yeasts. The four types of yeast used were adapted (Free EtOH-A, Encapsulated EtOH-A) and non-adapted to ethanol (Free, Encapsulated).The different yeast-inoculating formats had a significant impact on oxygen consumption and pressure increase rate in the bottle during the prise de mousse. Similarly to the free form, encapsulated yeast successfully completed the secondary fermentation. After an ageing period of 6 months, volatiles and sensory profiles of sparkling wines were compared. Although, some differences in volatile profiles were found among samples, sparkling wines produced by Encapsulated EtOH-A showed sensory properties, in terms of aroma, taste and body, similar to those produced by free yeast (both adapted and non-adapted to ethanol).

Influence of Leishmania (Viannia) braziliensis infection on the attractiveness of BALB/c mice to Nyssomyia neivai (Diptera: Psychodidae).

BackgroundPhlebotomine sand flies are vectors for several pathogens, with Leishmania being the most important. In Brazil, the main aetiological agent of American cutaneous leishmaniasis (ACL) is Leishmania (Viannia) braziliensis, and Nyssomyia neivai is one of its main vectors in São Paulo state and other areas of South America. Similar to other haematophagous insects, sand flies use volatile compounds called kairomones to locate their hosts for blood meals. A possible increase in the attractiveness of hosts infected with Leishmania infantum to their vectors has been demonstrated. In the present study, we aimed to investigate whether L. braziliensis-infected hosts present higher attractiveness to Ny. neivai and to identify differences in the volatile compounds released by infected and uninfected mice.ResultsBehavioural experiments in which sand fly females directly fed on infected or uninfected mice showed no significant differences in the attractiveness of the mice or the blood volume ingested. Y-tube olfactometer bioassays also revealed no significant differences in the attractiveness of these hosts to Ny. neivai. No differences were observed in the profiles of the volatile compounds released by the two groups of mice. However, PCA and cluster analysis were able to classify the 31 identified compounds into three clusters according to their abundances. This classification showed a possible role for individual variation in the absence of differences in volatile profiles and attractiveness between infected and uninfected mice.ConclusionIn this first cross-sectional study with an aetiological agent of ACL, there were no statistically significant differences in the attractiveness of infected hosts to their vector.