Occurrence and Analysis of Sulfur Compounds in Wine

Sulfur compounds play an important role in the sensory characteristics of wine. These molecules can derive from the grape, in which the non-volatile forms are usually present as glycosylated molecules, the metabolic activities of yeast and bacteria, the chemical reactions taking place during the wine aging and storage, and the environment. The sulfur compounds include molecules positively correlated to the aromatic profile of wine, namely the volatile thiols, and are responsible for certain defects, imparting notes described as cabbage, onion, rotten egg, garlic, sulfur and rubber. Due to the low concentration of these molecules in wine, their high reactivity and the matrix complexity, the analytical methods which enable their detection and quantification represent a challenge. The solid phase microextraction (SPME) technique has been developed for sulfur compounds associated with off-flavors. The analysis of volatile thiols usually requires a derivatization followed by gas chromatography (GC)-MS or UPLC-MS methods. Besides the sulfur-containing aromas, another sulfur compound that deserves mention is the reduced glutathione (GSH) which has been widely studied due to its antioxidant properties. The analysis of GSH has been proposed using a liquid chromatography technique (HPLC or UPLC) coupled with fluorescence, MS and UV detectors

Role of extraction procedures on the concentration of varietal thiol precursors in Grillo white grape must

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Acute cigarette smoking impairs microvascular function in young moderate smokers: A potential model for studying vasoactive properties of food bioactives

It has been suggested that several dietary compounds may improve endothelial dysfunction and oxidative stress induced by smoking. We investigated the effects of acute smoking on blood pressure, heart rate (HR), peripheral arterial function (reactive hyperemia index, RHI), and arterial stiffness in young smokers by Endo-PAT2000. Twenty subjects that smoked an average of 15 cigarettes per day participated in the study. Reactive Hyperemia Index, arterial stiffness, blood pressure and HR were assessed before and after smoking one cigarette. Acute smoking significantly reduced RHI by 28% while increased arterial systolic ( + 14%) and diastolic ( + 10%) blood pressure and HR ( + 13%) at 5 min, while no effect was observed after 30 min. Arterial stiffness was not significantly affected. A significant, positive correlation was found between total serum cholesterol concentration and post-smoking arterial stiffness values. This study demonstrates that acute cigarette smoking impairs RHI and vital signs in young moderate smokers as evaluated through a non-invasive technique. Additionally, the experimental model described, where a decrease of RHI is induced by cigarette smoking, may be useful to study the impact of dietary vasoactive compounds on endothelial function

Comparison between the Grape Technological Characteristics of Vitis vinifera Subsp. sylvestris and Subsp. sativa

none7siWine has been produced in Georgia since the 6th millennium BC. The processes of cultivar selection and breeding started with wild grapes Vitis vinifera L. ssp. sylvestris Gmel. and included multiple introgression events—from the wild to domestication. This article aims at improving the knowledge concerning the history of winemaking through a comparison of the Vitis vinifera subsp. sylvestris and subsp. sativa. Grapes of Vitis vinifera subsp. sylvestris were grown in an ampelographic collection and vintages 2017–2020 were analyzed. The obtained data were compared to a wider dataset available in literature concerning Vitis vinifera subsp. sativa, demonstrating the central role of grape morphology in the domestication process. This evidence suggests that the technological value of the cultivars played an important role in the selection process. In vintages 2017, 2018, and 2019, wines were produced with Vitis vinifera subsp. sylvestris grapes and compared with Cabernet Sauvignon and Saperavi vinifications. For all the vintages, the fermentations took shorter time for wild grape, despite the highest content of total phenols. Learning from the past, Vitis vinifera subsp. sylvestris might still be an interesting genetic resource for future breeding programs. Furthermore, the possible combination of wild and domesticated grapes can make possible the production of wines with long ageing, exalting their own characteristics.openMaghradze, David; Kikilashvili, Shengeli; Gotsiridze, Olan; Maghradze, Tamar; Fracassetti, Daniela; Failla, Osvaldo; Rustioni, LauraMaghradze, David; Kikilashvili, Shengeli; Gotsiridze, Olan; Maghradze, Tamar; Fracassetti, Daniela; Failla, Osvaldo; Rustioni, Laur

A single serving of blueberry (V. corymbosum) modulates peripheral arterial dysfunction induced by acute cigarette smoking in young volunteers: a randomized-controlled trial

Cigarette smoking causes oxidative stress, hypertension and endothelial dysfunction. Polyphenol-rich foods may prevent these conditions. We investigated the effect of a single serving of fresh-frozen blueberry intake on peripheral arterial function and arterial stiffness in young smokers. Sixteen male smokers were recruited for a 3-armed randomized-controlled study with the following experimental conditions: smoking treatment (one cigarette); blueberry treatment (300 g of blueberry) + smoking; control treatment (300 mL of water with sugar) + smoking. Each treatment was separated by one week of wash-out period. The blood pressure, heart rate, peripheral arterial function (reactive hyperemia and Framingham reactive hyperemia), and arterial stiffness (digital augmentation index, digital augmentation index normalized for a heart rate of 75 bpm) were measured before and 20 min after smoking with Endo-PAT2000. Smoking impaired the blood pressure, heart rate and peripheral arterial function, but did not affect the arterial stiffness. Blueberry consumption counteracted the impairment of the reactive hyperemia index induced by smoking (?\u274.4 ? 0.8% blueberry treatment vs. ?\u2722.0 ? 1.1% smoking treatment, p < 0.01) and Framingham reactive hyperemia (+28.3 ? 19.2% blueberry treatment vs. ?\u2742.8 ? 20.0% smoking treatment, p < 0.0001), and the increase of systolic blood pressure (+8.4 ? 0.02% blueberry treatment vs. +13.1 ? 0.02% smoking treatment, mmHg, p < 0.05) after cigarette smoking. No effect was observed for arterial stiffness and other vital signs. In conclusion, data obtained suggest a protective role of blueberry on reactive hyperemia, Framingham reactive hyperemia, and systolic blood pressure in subjects exposed to smoke of one cigarette. Future studies are necessary to elucidate the mechanisms involved

Microclimate of Grape Bunch and Sunburn of White Grape Berries: Effect on Wine Quality.

This research aimed to evaluate the composition of wines made with white grapes which are particularly susceptible to sunburn symptoms due to the absence of anthocyanin. Sunburn is a complex physiological dysfunction leading to browning or necrosis of berry tissues. In vintage 2021, the canopy of ‘Verdeca’ grapevines grown in Salento, South Italy, was differently managed by sun exposing or shading the bunches. Micrometeorological conditions were studied at different levels. Grapes were vinified, comparing the winemaking with and without skin maceration. The vegetative-productive balance of plants was not substantially modified. On the contrary, a significant effect was observed on the quality and quantity of grapes produced: smaller berries with sunburn symptoms were found on unshaded bunches. This influenced the percentage distribution among skin, pulp and seeds, causing a decrease in must yield of up to 30%. The pH was significantly higher in macerated wines made using shaded grapes, due to a lower titratable acidity and to significant impacts on the acid profile. Obviously, maceration produced a higher extraction of phenolics in wines, which reached their maximum in wines made with sunburned grapes. The absorbance at 420 nm, index of yellow color, was also significantly higher in sunburned grapes, indicating greater oxidation. Even though excessive grape sun-exposure could negatively affect the perception of white wines made without maceration (resulting in more oxidative character), the sensory quality of orange/amber wines was not significantly impacted by the presence of sunburned grapes. Thus, this winemaking technique could be particularly interesting to set up a production strategy adapted to viticultural regions strongly affected by climate change

Development of a novel liquid/liquid extraction and ultra-performance liquid chromatography tandem mass spectrometry method for the assessment of thiols in South African Sauvignon Blanc wines

Background and Aims: The thiol compounds, 3-mercaptohexan-1-ol (3MH) and 3-mercaptohexyl acetate (3MHA), are important, pleasant volatile thiols conferring fruity notes in wines. The analytical determination of these thiols in wine remains problematic due to their trace concentration and instability. The main aim of this study was to develop a liquid/liquid extraction and ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method for the determination of 3MH and 3MHA concentration in Sauvignon Blanc wines. Methods and Results: A novel sample preparation based on a liquid/liquid extraction was developed. Thiols were quantified by UPLC-MS/MS after derivatisation with o-phthaldialdehyde. Good results were obtained with the method in terms of limit of detection and of quantification, accuracy and repeatability. Average concentration of 3MH in 18 South African wines was 1320 and of 3MHA 313ng/L. Conclusions: The analytical method described enables the liquid/liquid extraction of 3MH and 3MHA from wine, separates them by liquid chromatography and detects them by MS/MS at a concentration lower than that of their sensory threshold. Significance of the Study: The determination of the concentration of 3MH and 3MHA in Sauvignon Blanc wines could enable wine producers to predict the sensory attributes of the wine

Identifying the Main Drivers in Microbial Diversity for Cabernet Sauvignon Cultivars from Europe to South Africa: Evidence for a Cultivar-Specific Microbial Fingerprint

Microbial diversity in vineyards and in grapes has generated significant scientific interest. From a biotechnological perspective, vineyard and grape biodiversity has been shown to impact soil, vine, and grape health and to determine the fermentation microbiome and the final character of wine. Thus, an understanding of the drivers that are responsible for the differences in vineyard and grape microbiota is required. The impact of soil and climate, as well as of viticultural practices in geographically delimited areas, have been reported. However, the limited scale makes the identification of generally applicable drivers of microbial biodiversity and of specific microbial fingerprints challenging. The comparison and meta-analysis of different datasets is furthermore complicated by differences in sampling and in methodology. Here we present data from a wide-ranging coordinated approach, using standardized sampling and data generation and analysis, involving four countries with different climates and viticultural traditions. The data confirm the existence of a grape core microbial consortium, but also provide evidence for country-specific microbiota and suggest the existence of a cultivar-specific microbial fingerprint for Cabernet Sauvignon grape. This study puts in evidence new insight of the grape microbial community in two continents and the importance of both location and cultivar for the definition of the grape microbiome.The YeSViTE project (FP7-IRSES-2013-GA612441) supported the secondments of J.T. and F.V. to the Stellenbosch University (South Africa) and R.F. to the Agrarian University of Georgia (Georgia), and the grape sampling in Tuscany carried out by D.F. This work was also supported by Winetech grant SU IWBT 16-02

Sustainability of food side streams: a case study of fermented blends made with sour whey and sunflower press cake powder using the back-slopping technique

The exploitation of by-products is a key factor to increase the sustainability of the agri-food chain and fermentation is a simple and eco-friendly process for achieving safe and suitable food materials. In this study, we investigated the possibility to manage a spontaneous fermentation of blends made with different proportions of two food side streams (bovine acid whey and sunflower press cake powder) through the application of a back-slopping technique of the mixed material incubated at 26°C in static conditions. A full-factorial 2-factor 3-level design of experiment was applied to infer the effect of the percent (w/w) of press cake powder in the mixture (20, 25, and 30%) and the rate of back-slopping inoculum (15, 30, and 45%). The pH value, titratable acidity, content of sugars, organic acids, and phenolic acids, enumeration of lactic acid bacteria, yeasts and molds, bacterial contaminants, presumptive Bacillus cereus, and Escherichia coli were measured for each fermentation step at 0, 24, 48, and 72 h. On the same samples, a metataxonomics analysis, targeted on bacterial 16S rRNA gene and fungal ITS region, was performed by using the Illumina MiSeq platform. Acidification of the blends (on average, starting pH = 5.45 ± 011, final pH = 4.61 ± 0.11; starting acidity =13.68 ± 1.02 °SH/50 mL, final acidity = 28.17 ± 2.92°SH/50 mL) and high LAB counts (on average, 9.39 log CFU/g ± 0.25) were observed at the end of each refreshment. In all fermented mixtures, B. cereus, E. coli, and molds counts were lower than the detection limit (&lt;2 log CFU/g), whereas bacterial contaminants, overall spore-formers, were always present (3.74 log CFU/g ± 0.27). After 72 h, the dropping of pH value was maximum, yielding significant differences compared to previous fermentation steps (p &lt; 0.01); particularly, the lowest pH (4.45 ± 0.06) was achieved in the central points of DoE (25% of press cake powder and 30% of back-slopping rate), representing the most suitable condition. Results from both culture-dependent and -independent techniques were consistent; although Lactococcus lactis, continuously deriving from the acid whey, was the main LAB, Pediococcus pentosaceus appeared and, in some cases, became the dominant species. Finally, a long-term trial (about 1 month), using the best condition previously pointed out, was performed with an extension of the incubation time to 84 h for each refreshment. The increase in acidity forced the natural selection toward acid-tolerant microbial strains confirming the former results. Although preliminary, these findings can be useful for developing innovative operations to manage these two relevant side streams implementing the circularity of food resources

Transcriptomics unravels the adaptive molecular mechanisms of Brettanomyces bruxellensis under SO2 stress in wine condition

CITATION: Valdetara, F. et al. 2020. Transcriptomics unravels the adaptive molecular mechanisms of Brettanomyces bruxellensis under SO2 stress in wine condition. Food Microbiology, 90. doi:10.1016/j.fm.2020.103483.The original publication is available at https://www.sciencedirect.com/journal/food-microbiologySulfur dioxide is generally used as an antimicrobial in wine to counteract the activity of spoilage yeasts, including Brettanomyces bruxellensis. However, this chemical does not exert the same effectiveness on different B. bruxellensis yeasts since some strains can proliferate in the final product leading to a negative sensory profile due to 4-ethylguaiacol and 4-ethylphenol. Thus, the capability of deciphering the general molecular mechanisms characterizing this yeast species’ response in presence of SO2 stress could be considered strategic for a better management of SO2 in winemaking. A RNA-Seq approach was used to investigate the gene expression of two strains of B. bruxellensis, AWRI 1499 and CBS 2499 having different genetic backgrounds, when exposed to a SO2 pulse. Results revealed that sulphites affected yeast culturability and metabolism, but not volatile phenol production suggesting that a phenotypical heterogeneity could be involved for the SO2 cell adaptation. The transcriptomics variation in response to SO2 stress confirmed the strain-related response in B. bruxellensis and the GO analysis of common differentially expressed genes showed that the detoxification process carried out by SSU1 gene can be considered as the principal specific adaptive response to counteract the SO2 presence. However, nonspecific mechanisms can be exploited by cells to assist the SO2 tolerance; namely, the metabolisms related to sugar alcohol (polyols) and oxidative stress, and structural compounds.https://www.sciencedirect.com/science/article/pii/S0740002020300721?via%3DihubPublishers versio