Utility of comprehensive GC×GC Gas Chromatography in finding varietal markers among volatile compounds in non-aromatic red wines

To investigate the utility of comprehensive GC×GC gas chromatography metabolomics in finding varietal markers among volatile compounds in non-aromatic red wines, representative samples of the two most important Croatian monovarietal red wines, Plavac mali and Teran, were subjected to analysis by both conventional gas chromatography–mass spectrometry (GC-MS) and comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry (GC×GC-TOF-MS) after headspace solid-phase microextraction (HS-SPME). GC-MS was useful for the determination of the basic volatile profile composed mainly of major esters and acids, followed by terpenes and C13-norisoprenoids. GC×GC-TOF-MS allowed the identification of 209 volatiles, among which 49 were significantly different across monovarietal wines. The compounds most characteristic for Teran were two theaspirane isomers, ethyl 3-(methylsulfanyl)propanoate, ethyl methyhexanoate, and ho-trienol, whereas Plavac mali stood out with higher concentrations of tridecane and a 2,3-butanediol isomer. The two monovarietal wines were successfully differentiated between each other by multivariate statistical methods mostly based on GC×GC-TOF-MS data. The presented approach that combines conventional GC-MS and advanced GC×GC-TOF-MS showed a great potential for tracking chemical markers of varietal origin and could be practically applied in managing wine production, quality and typicity, marketing, and protection from forger

Comprehensive lipid profile of ‘Maraština’ grape skins from Dalmatia

Lipids are a diverse group of organic compounds that serve essential roles due to their biological functions for all prokaryotic and eukaryotic organisms. Despite the fundamental role of lipid class in plants, there is still a relatively low level of knowledge regarding the composition of grape lipids. This research represents the first investigation into the lipids of the Croatian grape variety ‘Maraština’ (Vitis vinifera L.), employing a targeted approach and the UHPLC-MS/MS method to conduct a comprehensive analysis of the lipid profile of grape skins. The study investigated the profile of free fatty acids, glycerolipids, glycerophospholipids, triterpenoids, sphingolipids, and free fatty acid esters in eleven vineyards located along the cultivation area of ‘Maraština’ variety (Dalmatia, Croatia). Grape skins from vineyards that were exposed to more sunlight and higher daily temperature during the vegetation period mainly resulted in a richer profile of free fatty acids. Among lipids, ‘Maraština’ grape skins were characterized mainly by a triterpenoid compound; oleanolic acid (249.49 g/g of FW), and free fatty acids, especially palmitic acid C16:0 (26.09 g/g of FW), and lignoceric acid C24:0 (12.40 g/g of FW). Hierarchical clustering analysis represented valuable insights into the diversity of lipids in ‘Maraština’ grape skin

Development of a fully automated method HS-SPME-GC-MS/MS for the determination of odor-active carbonyls in wines: a "green" approach to improve robustness and productivity in the oenological analytical chemistry

The aim of this study was the optimization and validation of a green, robust, and comprehensive method for the determination of volatile carbonyl compounds (VCCs) in wines that could be added as a new quality control tool for the evaluation of a complete fermentation, correct winemaking style, and proper bottling and storage. A HS-SPME-GC-MS/MS method was optimized and automated using the autosampler to improve overall performance. A solvent-less technique and a strong minimization of all volumes were implemented to comply with the green analytical chemistry principles. There were as many as 44 VCC (mainly linear aldehydes, Strecker aldehydes, unsaturated aldehydes, ketones, and many other) analytes under investigation. All compounds showed a good linearity, and the LOQs were abundantly under the relevant perception thresholds. Intraday, 5-day interday repeatability, and recovery performances in a spiked real sample were evaluated showing satisfactory results. The method was applied to determine the evolution of VCCs in white and red wines after accelerated aging for 5 weeks at 50 °C. Furans and linear and Strecker aldehydes were the compounds that showed the most important variation; many VCCs increased in both classes of samples, whereas some showed different behaviors between white and red cultivars. The obtained results are in strong accordance with the latest models on carbonyl evolution related to wine agin

Application of a target-guided data processing approach in saturated peak correction of GC×GC analysis

5openInternationalItalian coauthor/editorDetector and column saturations are problematic in comprehensive two-dimensional gas chromatography (GC×GC) data analysis. This limits the application of GC×GC in metabolomics research. To address the problems caused by detector and column saturations, we propose a two-stage data processing strategy that will incorporate a targeted data processing and cleaning approach upstream of the “standard” untargeted analysis. By using the retention time and mass spectrometry (MS) data stored in a library, the annotation and quantification of the targeted saturated peaks have been significantly improved. After subtracting the nonperfected signals caused by saturation, peaks of coelutes can be annotated more accurately. Our research shows that the target-guided method has broad application prospects in the data analysis of GC×GC chromatograms of complex samples.openZhang, Penghan; Carlin, Silvia; Franceschi, Pietro; Mattivi, Fulvio; Vrhovsek, UrskaZhang, P.; Carlin, S.; Franceschi, P.; Mattivi, F.; Vrhovsek, U

In-depth characterization of the volatile aroma profile and other characteristics of white wine produced by sequential inoculation with a Lachancea thermotolerans starter yeast strain

The yeast Lachancea thermotolerans has the ability to produce notable amounts of lactic acid and reduce alcoholic strength in fermentation, so it has a considerable potential for mitigating negative impacts of climate changes in winemaking. In this study, a treatment with L. thermotolerans and Saccharomyces cerevisiae in sequential inoculation was compared to a control S. cerevisiae monoculture fermentation of Malvazija istarska (aka Malvasia Istriana) white grape must. Standard physico-chemical parameters of the obtained wines were determined by the OIV methods. Targeted (GC/FID and GC/MS) and untargeted (GC×GC/TOF-MS) gas chromatographic techniques were combined for the analysis of volatile compounds. Phenolic compounds were analyzed by UPLC/QqQ-MS/MS, and proteins by RP-HPLC-DAD, while a sensory analysis of wines was performed by a panel of trained and certified tasters. L. thermotolerans co-fermentation treatment increased the concentration of lactic acid and decreased alcoholic strength. L. thermotolerans increased the concentrations of geraniol, β-ionone, isobutanol, isobutyric acid, ethyl isobutyrate, several major acetates, ethyl lactate, and diethyl succinate, followed by many minor compounds. This wine also contained more hydroxycinnamoyl tartrates, while control S. cerevisiae wine had higher levels of free hydroxycinnamates. The effects on PR proteins were minor. L. thermotolerans co-fermentation slightly enhanced the sensory perception of tropical fruit, herbaceous, tobacco, and buttery odor notes, as well as fullness of body. With the largest number of identified volatile compounds up to date and other results obtained, this study contributes to the better understanding of oenological and especially aromatic potential of L. thermotolerans in white wine productio

MS imaging of small metabolites in fruits

MS Imaging of large molecules, e.g. proteins and lipids, have been reported with MALDI. On the other hand, few works have been done on mapping the small molecules by MALDI imaging. This is mainly due to the high chemical noise background interference in the low mass region caused by chemical matrices. DESI Imaging, however, could be complementary to MALDI in that sample can be analyzed directly without matrices. A large group of small metabolites are of considerable physiological and morphological importance in plants, e.g. flavonols involve in plant defense against environmental stresses and organic acids are one of important factors for fruit quality, but knowledge of their precise functions is limited due to insufficient characterization of their spatial responses. In this communication we will discuss methodological details about MS imaging of small metabolites in apple and grape in terms of sample preparation, imaging methods, and other experimental concerns by using MALDI [1] and DESI source coupled with a high resolution/accurate LTQ-Orbitrap mass spectrometer. Finally, we will describe the spatial distributions of flavonols and organic acids in apple and grape, respectively

Monoterpenoids isomerization and cyclization processes in Gewürztraminer wines: a kinetic investigation at different pH and temperatures

The evolution of volatile compounds in wine comprises several acid-catalyzed reactions, such as glycosides precursors’ hydrolysis and rearrangements, and significantly contributes to its sensory qualities, even after prolonged aging. The aim of this work was to use a well-defined experimental design and to examine how terpenoids in Gewürztraminer wine change over time when subjected to different temperatures and pH levels over two weeks. A theoretically-based approach was used, involving the definition of a complete system of ordinary differential equations (ODE) with well-established boundary conditions (initial concentration of reactants/products), using Kinetiscope, a kinetic simulation software. The calculated optimal rate constants, based on the experimental curves, produced a comprehensive data set describing the evolution of the terpenoid profile, highlighting the reversible and irreversible interconversion processes. Finding revealed that higher pH and lower temperature conditions are crucial for preserving the important terpenoid compounds that characterize the typicality and exemplarity of Gewürztraminer aroma profil

assessing the biodiversity of fermenting yeasts associated with marula fruits (Sclerocarya birrea)

The research work was funded by Botswana International University of Science and Technology (BIUST). © 2023 The Author(s). Published by Oxford University Press on behalf of the Guarantors of Brain.The inebriation of wild African elephants from eating the ripened and rotting fruit of the marula tree is a persistent myth in Southern Africa. However,the yeasts responsible for alcoholic fermentation to intoxicate the elephants remain poorly documented.In this study, we considered Botswana, a country with the world’s largest population of wild elephants, and where the marula tree is indigenous, abundant and protected, to assess the occurrence and biodiversity of yeasts with a potential to ferment and subsequently inebriate the wild elephants. We collected marula fruits from over a stretch of 800 km in Botswana and isolated 106 yeast strains representing 24 yeast species. Over 93% of these isolates,typically known to ferment simple sugars and produce ethanol comprising of high ethanol producers belonging to Saccharomyces, Brettanomyces, and Pichia, and intermediate ethanol producers Wickerhamomyces, Zygotorulaspora, Candida, Hanseniaspora, and Kluyveromyces. Fermentation of marula juice revealed convincing fermentative and aromatic bouquet credentials to suggest the potential to influence foraging behaviour and inebriate elephants in nature. There is insufficient evidence to refute the aforementioned myth. This work serves as the first work towards understanding the biodiversity marula associated yeasts to debunk the myth or approve the facts.publishersversionpublishe

Phlorizin released by apple root debris is related to apple replant disease

Autotoxic compounds are likely to be among the causes of apple replant disease, but their secretion is low during plant life. Using targeted metabolomics, the changes in soil phenolic profile were analyzed after the addition of apple roots, and their potential autotoxicity was assessed on apple seedlings. The addition of apple roots severely damaged the plants, attributed to autotoxic action of the phenolic compound phlorizin. Prolonged residence time of the roots in the soil before planting reduced their negative action, probably due to the degradation of phlorizin