Non-Targeted Metabolite Profiles and Sensory Properties Elucidate Commonalities and Differences of Wines Made with the Same Variety but Different Cultivar Clones

From the grapevine to the glass: A wine metabolomics tale by FT-ICR-MS

Wine is one of the most consumed beverages around the world. Its unique characteristics arise from numerous processes, from the selection of grapevine varieties and grapes, the effect of the terroir and geographical origin, through the biochemical process of fermentation by microorganisms, until its aging. All molecules found in wine define its chemical fingerprint and can be used to tell the story of its origin, production, authenticity and quality. Wine's chemical composition can be characterized using an untargeted metabolomics approach based on extreme resolution mass spectrometry. Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) is currently the most powerful analytical technique to analyse such complex sample, providing the most comprehensive analysis of the chemical fingerprint of wine.

Inter- and intra-varietal genetic variations co-shape the polyphenol profiles of Vitis vinifera L. grapes and wines

Inheritance and mutations are important factors affecting grape phenolic composition. To investigate the inter- and intra-varietal differences in polyphenolic compounds among grapes and wines, 27 clones belonging to eight varieties of Vitis vinifera L. were studied over two consecutive years. A total of 24 polyphenols (nine anthocyanins, three flavanols, five flavonols, and seven phenolic acids) were analyzed, and the physicochemical parameters of the grapes and wines were determined. Polyphenol profiles showed significant varietal and clonal polymorphisms, and malvidin-3-O-glucoside, peonidin-3-O- glucoside, and epicatechin were identified as key biomarkers distinguishing different grapes and wines when using an orthogonal partial least squares discriminant analysis. Further multivariate analysis classified these genotypes into three subclasses, and a somatic variant of 'Malbec', MBVCR6, had the most abundant polyphenolic compounds that were related to the titratable acid content. The current results reveal that varietal and clonal variations are important for obtaining wines with high polyphenol content.

Effects of alcoholic fermentation on the non-volatile and volatile compounds in grapefruit (Citrus paradisi Mac. cv. Cocktail) juice: A combination of UPLC-MS/MS and gas chromatography ion mobility spectrometry analysis

Grapefruit has attracted much attention as a functional fruit, of which “Cocktail” is a special variety with low acidity. The present study aimed to investigate the effects of alcoholic fermentation on the non-volatile and volatile compounds of “Cocktail” grapefruit juice. To analyze, a non-targeted metabolomics method based on UPLC-MS/MS and volatiles analysis using GC-IMS were performed. A total of 1015 phytochemicals were identified, including 296 flavonoids and 145 phenolic acids, with noticeably increasing varieties and abundance following the fermentation. Also 57 volatile compounds were detected, and alcoholic fermentation was effective in modulating aromatic profiles of grapefruit juice, with terpenes and ketones decreasing, and alcohols increasing together with esters. Citraconic acid and ethyl butanoate were the most variable non-volatile and volatile substances, respectively. The results provide a wealth of information for the study of “Cocktail” grapefruit and will serve as a valuable reference for the large-scale production of grapefruit fermented juice in the future.

LC-MS-Based Metabolomics Discriminates Premium from Standard Chilean cv. Cabernet Sauvignon Wines from Different Valleys

Cabernet Sauvignon grapes in Chile, mainly grown between the 30° S and 36° S, account for more than 30% of Chilean wine production, and yield wines with different characteristics which influence their quality. The aim of this study was to apply a liquid chromatography – mass spectrometry (LC–MS)-based metabolomic protocol to investigate the quality differentiation in a sample set of monovarietal wines from eight valleys covering 679 km of the north-south extension. All samples were produced using a standardized red winemaking process and classified according to a company categorization in two major groups: premium and standard, and each group in two subcategories. The results pointed out that N-containing metabolites (mainly small peptides) are promising biomarkers for quality differentiation. Moreover, the premium wines were characterized by higher amounts of anthocyanins and other glycosylated and acetylated flavonoids, as well as phenolic acids; standard quality wines, on the other hand, presented stilbenoids and sulfonated catabolites of tryptophan and flavanols.

Metabolomics: An analytical technique for food processing evaluation

This review aimed to retrieve the most recent research with strong impact concerning the application of metabolomics analysis in food processing. The literature reveals the high capacity of this methodology to evaluate chemical and organoleptic transformations that occur during food production. Current and potential applications of metabolomics analysis will be addressed, focusing on process-composition-function relationships. The use of the metabolomics approach to evaluate transformations in foods submitted to minimal processes, heat or cold treatments, drying, fermentation, chemical and enzymatic treatments and processes using innovative technologies will be discussed. Moreover, the main strategies and advantages of metabolomics-based approaches are reviewed, as well as the most used analytical platforms. Overall, metabolomics can be seen as an important tool to support academia and industry on pursuing knowledge about the transformation of raw animal or plant materials into ready-to-eat products.

Characterization of Tempranillo negro (VN21), a high phenolic content grapevine Tempranillo clone, through UHPLC-QqQ-MS/MS polyphenol profiling

Grapevine cultivar and clone genotype is an important factor in the phenolic composition of wine. In this study, a new intense dark black berry color variant of Tempranillo, known as Tempranillo negro or VN21, is described. A targeted chromatographic approach based on UHPLC-QqQ-MS/MS was used to study the anthocyanins and non-colored phenols of the grape berry (skin and seeds) and wine. RJ43, one of the most cultivated clones in D.O.Ca. Rioja (Spain), was analyzed for comparison. Results suggest that the unique color of the grape skin in Tempranillo negro could be explained by higher concentrations of peonidin and cyanidin derivatives. This genotype accumulated anthocyanins in the seeds. Those differences in the berry were enhanced in the VN21 wines, which displayed notably higher concentrations of anthocyanins, and significantly increased contents of proanthocyanidins and stilbenes. This study exemplifies the application of phenol chromatographic analyses of spontaneous somatic variants to grapevine clonal selection.

Special Issue on "Fruit Metabolism and Metabolomics"

Over the past 10 years, knowledge about several aspects of fruit metabolism has been greatly improved. Notably, high-throughput metabolomic technologies have allowed quantifying metabolite levels across various biological processes, and identifying the genes that underly fruit development and ripening. This Special Issue is designed to exemplify the current use of metabolomics studies of temperate and tropical fruit for basic research as well as practical applications. It includes articles about different aspects of fruit biochemical phenotyping, fruit metabolism before and after harvest, including primary and specialized metabolisms, and bioactive compounds involved in growth and environmental responses. The effect of genotype, stages of development or fruit tissue on metabolomic profiles and corresponding metabolism regulations are addressed, as well as the combination of other omics with metabolomics for fruit metabolism studies.