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

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

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

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

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

Nicotinic acid and nicotinamide on pear and apple flowers are not limiting factors for Erwinia amylovora growth when these chemicals are considered in relation to cultivar and flower age

Fire blight, caused by Erwinia amylovora, is a devastating disease of pear (Pyrus communis) and apple (Malus × domestica) in many areas of the world. The disease is often initiated by epiphytic populations that multiply on flowers and colonize the hypanthia. In vitro, E. amylovora requires nicotinic acid (NicAc) and/or nicotinamide (NicNH2) as essential growth factors. The amount of NicAc on pear hypanthia was positively correlated with the altitude of the growing site and was inversely correlated with the sum of the maximum temperatures in the 30 days before flowering. The sum of the amounts of NicAc and NicNH2 on the hypanthia was about 6 to 23 times higher in pear, and about 1.2 to 3.5 times higher in apple, than the amounts of NicAc or NicNH2 necessary to support maximum E. amylovora growth  in vitro. No correlation was found between the amounts of NicAc and NicNH2 on the hypanthia of different pear and apple cultivars and at different growth stages and the growth of E. amylovora after experimental inoculation. In conclusion, NicAc and NicNH2 are essential for E. amylovora growth but the amounts of these chemicals on pear and apple flowers do not limit the establishment of the pathogen when competing bacteria are lacking

Grape lipidomics: an extensive profiling thorough UHPLC–MS/MS method

8openInternationalItalian coauthor/editorLipids play many essential roles in living organisms, which accounts for the great diversity of these amphiphilic molecules within the individual lipid classes, while their composition depends on intrinsic and extrinsic factors. Recent developments in mass spectrometric methods have significantly contributed to the widespread application of the liquid chromatography-mass spectrometry (LC–MS) approach to the analysis of plant lipids. However, only a few investigators have studied the extensive composition of grape lipids. The present work describes the development of an ultrahigh performance liquid chromatography tandem mass spectrometry (UHPLC–MS/MS) method that includes 8098 MRM; the method has been validated using a reference sample of grapes at maturity with a successful analysis and semi-quantification of 412 compounds. The aforementioned method was subsequently applied also to the analysis of the lipid profile variation during the Ribolla Gialla cv. grape maturation process. The partial least squares (PLS) regression model fitted to our experimental data showed that a higher proportion of certain glycerophospholipids (i.e., glycerophosphoethanolamines, PE and glycerophosphoglycerols, PG) and of some hydrolysates from those groups (i.e., lyso-glycerophosphocholines, LPC and lyso-glycerophosphoethanolamines, LPE) can be positively associated with the increasing °Brix rate, while a negative association was found for ceramides (CER) and galactolipids digalactosyldiacylglycerols (DGDG). The validated method has proven to be robust and informative for profiling grape lipids, with the possibility of application to other studies and matrices.openMasuero, Domenico; Škrab, Domen; Chitarrini, Giulia; Garcia-Aloy, Mar; Franceschi, Pietro; Sivilotti, Paolo; Guella, Graziano; Vrhovsek, UrskaMasuero, D.; Škrab, D.; Chitarrini, G.; Garcia-Aloy, M.; Franceschi, P.; Sivilotti, P.; Guella, G.; Vrhovsek, U

Exploratory analysis of commercial olive-based dietary supplements using untargeted and targeted metabolomics

8openInternationalItalian coauthor/editorThe market of olive-based dietary supplements (OBDS) is composed of a broad range of natural extracts claiming different health effects and often sold without a clear statement on their chemical composition. The aim of this survey was to characterize the chemical profiles of 14 commercially available OBDS. As many as 378 compounds were tentatively annotated in the analyzed samples. Although for most of metabolites the annotation at level I was prevented due to the lack of the analytical standard, the spectra obtained from high-resolution tandem mass spectrometry (MS/MS) measurements were very informative, allowing annotation of dozens of metabolites at level II or III. A targeted method allowed the quantification of 26 selected compounds. A large qualitative and quantitative variability was observed. The products obtained from buds by glyceric maceration were those with the lowest concentrations of all the quantified elements. The dose of 5 mg of hydroxytyrosol, corresponding to the European Food Safety Authority (EFSA) health claim, was only reached by four products, all of them originating from the olive fruit or the leaves. If we also take into consideration oleuropein, two additional products provide this daily amount. This work demonstrates the high complexity and diversity in the composition of OBDSopenGarcia Aloy, M.; Groff, N.; Masuero, D.; Nisi, M.; Franco, A.; Battelini, F.; Vrhovsek, U.; Mattivi, F.Garcia Aloy, M.; Groff, N.; Masuero, D.; Nisi, M.; Franco, A.; Battelini, F.; Vrhovsek, U.; Mattivi, F