Scale effect of viticultural zoning: effect of macro-terroir and basic terroir unit in Chianti Classico D.O.C.G. (Italy)

By Simone Priori
Terroir is a concept used to explain the specific combination and interaction of natural and human factors that affect distinctive wine characteristics. Soil and geology effects are sometimes considered considered less important than either climate or the human component. This post briefly describes a study carried out on one of the largest farms of the “Chianti Classico” wine district (Tuscany, Italy), focused on the effect of terroir on wine characteristics using two different zoning scales. At macro-terroir (MT), vineyards were carefully chosen based on lithology, soilscape, morphology, and mesoclimate. This study demonstrates that characteristics of pedo-geological landscapes can be used for a wine district zoning, while a more detailed soil mapping, leading to Unité Terroir de Base identification, is needed for differentiating wine characteristics. Find out more

Norisoprenoids and aroma precursors in early-harvested grapes

By Maurizio Petrozziello, Andriani Asproudi and Alessandra Ferrandino
Climate change can influence winemakers to anticipate the harvest to limit alcohol content in wine and to provide satisfactory concentration of secondary metabolites in the grapes. This post describes a study carried out to understand the link between grape ripening, seasonal trend and wine aroma. Aromatic profile of Barbera and Pinot Noir wines, produced with early harvested grapes was assessed. Considering that norisoprenoids are important contributors to wine aroma, attention was focused on these compounds during both alcoholic fermentation and after three months of storage. At the end of fermentation, the highest β-damascenone content was detected in wines obtained from less ripe grapes, the content subsequently increased significantly after three months of storage; however, the levels of β-ionone decreased significantly during the same period. The reduction of wine alcohol as a result of harvesting earlier, especially for Barbera, was associated with optimal aromatic levels as well as good technological parameters. Find out more

Understanding the green character in red wines by a sensory-directed approach

By Sara Ferrero del Teso, María-Pilar Sáenz Navajas, Ignacio Arias Pérez, Purificación Fernández Zurbano, Ana Escudero, Vicente Ferreira
This post results from a study done with the aim of define the “green character” of red wines and characterise the groups of molecules potentially involved in that perception. Wines were screened by wine experts for different levels of green character. Phenolic fractions were obtained by liquid chromatography (LC) and further submitted to sensory and chemical characterisation. The volatile fraction was screened by semipreparative LC, gas chromatography-olfactometry (GC-O) and quantitative analysis. The green character was associated to vegetal aroma, astringency, green and dry tannins. No specific aroma compounds were identified in the GC-O evaluation of green wines, however the wines contained higher levels of fusel alcohols. The interaction between isoamyl alcohol and the anthocyanin-derivative fraction and/or tannins is suggested to be involved in the formation of green character in red wines. Find out more

Effect of Botrytis and Penicillium on quality of passito Amarone wine

By Barbara Simonato, Marilinda Lorenzini, Giacomo Zapparoli
This study analysed chemical composition and sensory properties of Amarone wines produced from withered grapes artificially contaminated by Botrytis cinerea and Penicillium spp. Changes in properties of the two wines were evident by comparing wines obtained from healthy grapes used as controls. Penicillium infection affects aroma and sensory profile with respect to wine produced from heathy and botrytized grapes. The differences observed between the two Penicillium wines suggest that the impact on Amarone wine quality may be potentially different depending on the contaminant species of withered grapes. Moreover, strain-species effects cannot be excluded, and it will be possible to assess them in further investigations. Find out more

Chemistry and photochemistry inspired by the colors of grapes and red wines

By Cristiane Copetti
Oxidative stress is caused by the insufficient capacity of biological systems to neutralize reactive species produced in excess. A serious imbalance between the generation of reactive oxygen species (ROS) and antioxidant (AOX) protection in favor of the former causes excessive oxidative damage in cells and tissues because the ROS excessive production is associated with disruption of cell cycle regulatory mechanisms. Results obtained suggest that wine is a potential antioxidant and have positive effect against reactive species generated in SH-SY5Y cells, suggesting a neuroprotective effect. Find out more

Metabolomics in the field, walking through the chemical diversity of grape

By Arnaud Lanoue
Polyphenols are grape compounds with numerous health benefit and organoleptic properties. These compounds act as key components of the plant defense system against diseases. Herein, are discussed the results of an innovator metabotyping (metabolite-phenotype characterization) study using different grape varieties. A field experiment was setting up with uniform pedo-climatic factors and viticultural practices of growing vines to favor the genetic determinism of polyphenol expression. Metabolite correlation network suggested that several polyphenol subclasses were differently controlled. In a near future, the present polyphenol metabotyping approach coupled to multivariate statistical analyses might assist grape selection programs to improve metabolites with health-benefit potential and plant defense traits Find out more

Chemistry and photochemistry inspired by the colors of grapes and red wines

By Frank H. Quina
Anthocyanins and pyranoanthocyanins are major contributors to the color of red wines. These pigments are cationic below about pH 3, highly colored, non-toxic, reasonably soluble in water or alcohol and stable to light. They exhibit good antioxidant or antiradical activity and, as part of our diet, confer several important health benefits. excited state proton transfer in uncomplexed anthocyanins or pyranoanthocyanins and ultra-rapid direct deactivation of the excited state in copigmented anthocyanins, contribute to make the color of anthocyanins and pyranoanthocyanins quite resistant to fading in sunlight. Find out more

Healthy grapes for a good microbiome and wine

By Maria del Carmen Portillo
Wine quality depends of several factors, being grapes quality one of the most important ones. In the world, the main losses in viticulture are related with chemical composition and the grape microbiota. Rotten grapes might affect the alcoholic fermentation and, therefore, wine quality. In this post are discussed the results obtained in a study aimed to establish the relationship between the sour rot and Botrytis infection affecting Macabeo grapes with specific changes on the grape microbiota. Find out more

Red wines from northeastern Brazil: an abundant source of biologically active phenolics

By Eduardo de J. Oliveira
A phenolic-rich fraction extracted from red wine from the São Francisco valley, Northeastern Brazil, was chemically characterized and its hypotensive and antioxidant effects on spontaneously hypertensive rats were studied both in vitro and in vivo. Liquid chromatography coupled to mass spectrometry analysis showed that this fraction was rich in flavonols, flavonol glycosides, phenolic acids and anthocyanins. Pre-treatment of spontaneously hypertensive rats with this wine fraction by gavage for 15 days decreased mean arterial pressure and heart rate as well as serum lipid peroxidation. This demonstrate it is possible for phenolic constituents of red wine that are orally bioavailable to exert in vivo hypotensive and antioxidant effects on intact endothelial function. Find out more

Modulation of wine astringency by mannoproteins –salivary protein/mannoprotein/polyphenol interactions

By Alba Ramos-Pineda, Ignacio García-Estévez, M. Teresa Escribano-Bailón

The oral sensation called astringency is commonly described as drying, roughing and puckering in the mouth epithelia. Since some polyphenols are able to bind salivary proteins, namely PRPs, they can form insoluble tannin-protein precipitates in the mouth, causing a loss of lubrication and increased friction in the oral cavity, which would explain its astringency. This mechanism is thought to be the main responsible of wine astringency. Results obtained indicate the existence of interactions between mannoproteins and flavonols but also between mannoproteins and salivary proteins, suggesting a possible formation of protein/polyphenol/polysaccharide ternary complex that probably affects the astringency perception.

Find out more

Characterization of the aroma profile of wines by solid-phase microextraction using polymeric ionic liquid sorbent coatings

By Leandro Wang Hantao
Aroma is one the main factors contributing to the quality of wine and sets the difference between a vast number of wines and wine styles produced throughout the world. The volatile organic compounds (VOCs) are a highly complex fraction of wine with more than 1.000 volatile compounds reported so far. Headspace solid-phase microextraction (HS-SPME) is a solvent less, equilibrium-based sample preparation technique that combines sampling and sample preparation into a single step, which may be performed relatively fast and under mild extraction conditions. HS-SPME is likely the ideal tool for aroma profiling of wines because it requires minimal sample handling and it bypasses the co-isolation of non-volatile organic compounds. Find out more

Does blind wine tasting work? Investigating the impact of training on blind tasting accuracy and wine preference

Qian Janice Wang and Domen Prešern
Blind wine tasting refers to the practice of tasting a wine without seeing the label, and deducing the grape variety, location of origin, and vintage of the wine based on what one perceives and infers from the glass. Earlier this year, as the Oxford University Blind Tasting Society started their training season, we had a unique opportunity to follow the progress of a group of relatively novice tasters as they went through the intensive five-week training program under the watchful eye of long-time coach and Oxford Companion to Wine contributor, Hanneke Wilson. The study, funded by an American Association of Wine Economists research scholarship, aimed to get a longitudinal view of expertise acquisition over an intense period of blind tasting training, where participants attend multiple tastings a week over a period of 36 days. Find out more

ABOUT ME

My name is Paula Silva, I am an assistant professor in the Institute of Biomedical Sciences Abel Salazar (ICBAS) of University of Porto (UPorto) and I decided to have this blog to share my love by Science & Wine Find out more

CONNECT WITH ME