Biogenic Volatiles Emitted from Four Cold-Hardy Grape Cultivars During Ripening

In this research dataset, we summarize for the first time volatile organic compounds (VOCs) emitted in vivo from ripening wine grapes. We studied four cold-hardy cultivars grown in the Midwestern U.S.: St. Croix, Frontenac, Marquette, and La Crescent. These cultivars have gained popularity among local growers and winemakers, but still very little is known about their performance compared with long-established V. vinifera grapes. Volatiles were collected using two novel approaches: biogenic emissions from grape clusters on a vine and single grape berries. A third approach was headspace collection of volatiles from crushed grapes. Solid-phase microextraction (SPME) was used to collect volatiles. Vacuum-assisted SPME was used in the case of single grape berry. Collected VOCs were analyzed using separation and identification on a gas chromatograph mass spectrometer (GC-MS). More than 120 VOCs were identified using mass spectral libraries. The dataset provides evidence that detecting biogenic emissions from growing grapes is feasible. The dataset provides a record of temporal and spatial variability of VOCs, many of which could potentially impart aroma and flavor in the wine. The number of VOCs detected followed the order from single berry (the least) to crushed berry (the most). Thus, more information for potential use in harvesting in order to obtain the desired flavor is found in data from crushed grapes

Chemical and sensory evaluation of volatile aroma compounds from selected cold-hardy grapes and wines

Hybrid wine grape cultivars such as St. Croix (E.S. 283 x E.S. 193), Brianna (‘Kay Gray’ x E.S. 2-12-13), Frontenac (‘Landot 4511’ x University of Minnesota 89), La Crescent (‘St. Pepin’ x E.S. 6-8-25), Frontenac gris (single bud sport cane from ‘Frontenac’), Marquette (MN 1094 x Ravat 262) have been developed to be cold-hardy and disease-resistant in order to thrive in the cold climates such as the upper Midwest. Grape growers, area of grape production, wineries, and wine production has been increasing since the early 2000. The Iowa wine industry generated a $420 million (USD) economic impact in 2012. Cold-climate winemakers will encounter difficulties otherwise not encountered in areas where vinifera thrive. These struggles include high titratable acidity and low tannins, resulting in the perceptions of tartness and a lack of body and mouthfeel. Data about aroma profiles from volatile organic compounds of these grapes and wines are also lacking. To investigate the phenolic content of Marquette, Frontenac and St. Croix grape skins and seeds, at veraison and harvest, pigments and anthocyanins were exhaustively extracted, assayed by protein precipitation and bisulfite bleaching, and analyzed by spectrophotometer. Total tannins (from skins and seeds) decreased from veraison to harvest (0.62 mg catechin equivalents or CE per berry to 0.30 mg CE/berry). Monomeric pigments accounted for over 50% of the total color at pH 4.9. Short and long polymeric pigments accounted for less than 25% of the total color at pH 4.9. To investigate the volatile organic compounds emitted in-vivo from Frontenac, Marquette, St. Croix, and La Crescent during ripening, two novel SPME sampling devices were developed and metabolites were analyzed by GC-MS. PCA analysis of these volatile metabolites accounted for 26.8-79.9 percent of the variability, and a comprehensive summary of these metabolites was reported. To investigate the effects of harvest time on aroma profile of wines, berries of Marquette, Frontenac, Frontenac gris and Brianna were harvested at different time points and research wines were made. Research wines were analyzed by an automated headspace SPME-GCMS-olfactometry method, and a comprehensive summary of these volatile organic compounds was reported

Evaluation of Volatile Metabolites Emitted In-Vivo from Cold-Hardy Grapes during Ripening Using SPME and GC-MS: A Proof-of-Concept

In this research, we propose a novel concept for a non-destructive evaluation of volatiles emitted from ripening grapes using solid-phase microextraction (SPME). This concept is novel to both the traditional vinifera grapes and the cold-hardy cultivars. Our sample models are cold-hardy varieties in the upper Midwest for which many of the basic multiyear grape flavor and wine style data is needed. Non-destructive sampling included a use of polyvinyl fluoride (PVF) chambers temporarily enclosing and concentrating volatiles emitted by a whole cluster of grapes on a vine and a modified 2 mL glass vial for a vacuum-assisted sampling of volatiles from a single grape berry. We used SPME for either sampling in the field or headspace of crushed grapes in the lab and followed with analyses on gas chromatography-mass spectrometry (GC-MS). We have shown that it is feasible to detect volatile organic compounds (VOCs) emitted in-vivo from single grape berries (39 compounds) and whole clusters (44 compounds). Over 110 VOCs were released to headspace from crushed berries. Spatial (vineyard location) and temporal variations in VOC profiles were observed for all four cultivars. However, these changes were not consistent by growing season, by location, within cultivars, or by ripening stage when analyzed by multivariate analyses such as principal component analysis (PCA) and hierarchical cluster analyses (HCA). Research into aroma compounds present in cold-hardy cultivars is essential to the continued growth of the wine industry in cold climates and diversification of agriculture in the upper Midwestern area of the U.S

Miniaturised air sampling techniques for analysis of volatile organic compounds in air

Growing concern about the effects of atmospheric pollutants on climate and human health has accelerated the development of novel analytical methods, including sampling systems, for the determination of atmospheric volatile organic compounds (VOCs). Miniaturised air sampling (MAS) techniques have attracted wide attention in the past two decades due to their advantages (ease of operation, time-integrated sampling, small/no organic solvent consumption, and potential for automation). This review focuses on the latest developments in these techniques, including needle trap microextraction (NTME), in-tube extraction (ITEX), sorption trap, solid-phase microextraction (SPME fibre, SPME Arrow, and retracted SPME fibre), thin-film microextraction (TFME), solid-phase dynamic extraction (SPDE), and stir bar sorptive extraction (SBSE). Further, their benefits, drawbacks, and applicability to air sampling are discussed. The applications of MAS techniques for the analysis of atmospheric air, indoor air, breath air, and emissions of plants and foods are summarised and discussed.Peer reviewe

Methyl salicylate as a signaling compound that contributes to forest ecosystem stability

Methyl salicylate (MeSA) is a volatile plant and microbial signaling compound involved in systemic acquired resistance (SAR) and defense against pests and microbial pathogens, and antagonists. MeSA emitted by plants is also believed to trigger SAR in neighboring plant individuals, thus contributing to the resilience of the entire plant community. In this review, we discuss volatile plant-to-plant communication processes with a special focus on MeSA and provide an overview about the occurrence of MeSA in fungi and other microbes. We summarize present findings on the role of MeSA in plants and particularly in birches (Betula spp.) and discuss the potential use of MeSA and MeSA-emitting plants in agriculture and forestry. MeSA levels in plant tissues are adjusted by methylation of salicylic acid to MeSA and the reverse process of demethylation. Some plant species possess constitutively high MeSA levels and thus are suitable for experiments of admixture of high MeSA plants, e.g., birches of the subgenera Betulenta and Acuminata in plant communities such as mixed forests. Furthermore, knowledge of candidate genes and the molecular pathways underlying high MeSA emission is expected to offer a basis for altering MeSA levels and/or the selection of high MeSA mutants.Humboldt-Universität zu Berlin (1034)Peer Reviewe

Volatilomics of Natural Products: Whispers from Nature

Volatilomics studies the emission of volatile compounds from living organisms like plants, flowers, animals, fruits, and microorganisms, using metabolomics tools to characterize the analytes. This is a complex process that involves several steps like sample preparation, extraction, instrumental analysis, and data processing. In this chapter, we provide balanced coverage of the different theoretical and practical aspects of the study of the volatilome. Static and dynamic headspace techniques for volatile capture will be discussed. Then, the main techniques for volatilome profiling, separation, and detection will be addressed, emphasizing gas chromatographic separation, mass spectrometry detection, and non-separative techniques using mass spectrometry. Finally, the whole volatilome data pre-processing and multivariate statistics for data interpretation will be introduced. We hope that this chapter can provide the reader with an overview of the research process in the study of volatile organic compounds (VOCs) and serve as a guide in the development of future volatilomics studies

Postharvest Management of Fruits and Vegetables

All articles in the presented collection are high-quality examples of both basic and applied research. The publications collectively refer to apples, bananas, cherries, kiwi fruit, mango, grapes, green bean pods, pomegranates, sweet pepper, sweet potato tubers and tomato and are aimed at improving the postharvest quality and storage extension of fresh produce. The experimental works include the following postharvest treatments: 1-methylcycloprpene, methyl jasmonate, immersion in edible coatings (aloe, chitosan, plant extracts, nanoemulsions, ethanol, ascorbic acid and essential oils solutions), heat treatments, packaging, innovative packaging materials, low temperature, low O2 and high CO2 modified atmosphere, and non-destructible technique development to measure soluble solids with infra- and near infra-red spectroscopy. Preharvest treatments were also included, such as chitosan application, fruit kept on the vine, and cultivation under far-red light. Quality assessment was dependent on species, treatment and storage conditions in each case and included evaluation of color, bruising, water loss, organoleptic estimation and texture changes in addition to changes in the concentrations of sugars, organic acids, amino acids, fatty acids, carotenoids, tocopherols, phytosterols, phenolic compounds and aroma volatiles. Gene transcription related to ethylene biosynthesis, modification of cell wall components, synthesis of aroma compounds and lipid metabolism were also the focus of some of the articles

Biological responses and control of California red scale Aonidiella aurantii (Maskell) (Hemiptera: Diaspididae)

In many citrus areas around the world and within citrus-producing regions of Australia, the California red scale (CRS), Aonidiella aurantii (Maskell) (Hemiptera: Diaspididae), is considered the most important pests of citrus. The main biological control agents of Ao. aurantii in this zone are the parasitoid Aphytis melinus DeBach (Hymenoptera: Aphelinidae). In order to improve the biological control of Ao. aurantii several biotic and abiotic factors were studied, that may affect the efficiency of A. melinus in the laboratory and the field. More concretely, reproductive potential and age-specific fecundity schedules of Ao. aurantii were studied in the laboratory at constant temperatures (20, 23 and 27°C), while the biological parameters of its parasitoid A. melinus were conducted at 27°C. Results revealed that the net reproduction rate (Ro) was considerably higher for Ao. aurantii than A. melinus, which reached 28.14 at 27°C, indicating its high reproductive capacity. Moreover, the net reproduction rate obtained for A. melinus indicates a low substitution potential for each female having Ao. aurantii as a host under laboratory conditions. The intrinsic rate of increase (rm) of A. melinus (0.188 ♀/♀/day) was significantly greater than that of Ao. aurantii (0.080) at 27°C. Plants produce volatile organic compounds (VOCs) in response to herbivore attack, and these VOCs can be exploited by parasitoids of the herbivore as host location cues. The VOCs from non-infested and Ao. aurantii-infested citrus fruit were investigated using headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS). The data showed that more than 52 different compounds were identified, and different emissions associated attributed to herbivore activity were found for all fruit species (lemon, orange, mandarin and Tahitian lime). However, a single compound was exclusively produced by infested lemon fruit, while two compounds were significantly increased, and two compounds were only present in non-infested lemon. Five compounds were significantly increased in infested mandarins. For orange, five compounds were increased, and five compounds were exclusively presented in infested fruit. For lime fruit, eighteen of these compounds were increased, one was decreased, whereas five compounds were produced exclusively from infested lime fruit. Two putative herbivores-induced plant volatiles, d-limonene and β-ocimene, were significantly increased by Ao. aurantii infestation in all infested fruit, regardless of the citrus species. Subsequently, the preferences of female parasitoid on infested or healthy fruit in olfactometer bioassays were evaluated. Then in order to understand the magnitude of volatile attractiveness, the innate attractiveness of VOCs to A. melinus females in varying densities were tested in the laboratory. The results of the olfactometer assays that tested the behaviour of A. melinus to the different compounds emitted from infested and non-infested citrus fruit showed no such preference when compared between non-infested and infested oranges, mandarins and lime fruit; whilst, there were significant preferences for lemon fruit infested with Ao. aurantii over non-infested ones. For assessment, the attraction of synthetic Herbivore induced plant volatiles (HIPVs), four different concentrations (5,10, 15 and 20 μl/ml) of d-l-limonene and β-ocimene were investigated. However, mated A. melinus females preferred the reward-associated VOC more than hexane control in the case of d-limonene at the tested dosages of 15 and 20 μl/ml, β-ocimene at tested dosages of 10, 15 and 20 μl/ml. Finally, this study evaluated the dispersal ability of released A. melinus adults and their effect on the parasitism percentage, using d-limonene and β-ocimene with yellow sticky traps and scoring percentage parasitism on infested fruit. Under field conditions, the natural enemies’ effectiveness in controlling pests is largely correlated with their capability to spread towards infested crops. In this study, d-limonene and β-ocimene were examined for their attractiveness to California red scale parasitoid A. melinus in the field after augmentative releases. Field experiments demonstrated that lures baited with isolates of d-limonene and\or β-ocimene, which significantly attracted some species of natural enemies but had no significant impact on others. The number of A. melinus captured during the whole trial was greater in the traps treated with volatiles than the control. Finally, the overall parasitism rates were not increased by synthetic HIPV lures, but there was evidence that lures may increase parasitism of California red scale when there is a decrease in the amount of volatile organic compounds due to lack of healthy and infested fruit. In conclusion, HIPVs can potentially play important roles in attracting and exploiting natural enemies to reduce pest infestations