Polyphenols are an important constituent of wines and they are largely studied due to their antioxidant properties and for their effects on wine quality and stability, which is also related to their capacity to bind to proteins. The effects of some selected polyphenols, including procyanidins B1 and B2, tannic acid, quercetin, and rutin, as well as those of a total white wine procyanidin extract on the conformational properties of the major wine protein VVTL1 (Vitis vinifera Thaumatin-Like-1) were investigated by Synchrotron Radiation Circular Dichroism (SRCD). The data demonstrate the existence of an interaction between polyphenols and VVTL1, which results in modification of its thermal and UV denaturation pattern. This information can be useful in understanding the behavior of wine proteins in presence of polyphenols, thus giving new insights on the phenomena that are involved in wine stability.
This is the last post of 2019. The second year of Science & Wine existence, time for a brief reflection. This was a great year!
This post reports the development of a new strategy based on the accelerated hydrolysis of reconstituted phenolic and aromatic fractions (PAFs) extracted from grapes. It was possible to identify by GC-Olfactometry and GC–MS at least 30 different odorants including lipid derivatives, volatile phenols, vanillins, norisoprenoids, terpenes, bencenoids and 3-mercaptohexanol.
This work fits into a more general context related to the revalorization of agri-food by-products, which is extremely current for both environmental and economic reasons.
Results from this paper are stimulating for the flavor industry. It suggests that all simple fragrance materials could be advantageously replaced by much smaller levels of complex mixtures.
T2,4,6-trihydroxyphenanthrene (THP) results from cyclization of the trans-to the cis-isomer of resveratrol one of the most abundant polyphenols in red grapes and red wine. It has been demonstrated that THP can induce DNA damage through a pro-oxidant mechanism. On the other hand, due to the extended delocalization and conjugation of the πelectrons over the entire molecule, THP displays a significantly increased antioxidant activity compared to RSV with potential benefits on human health. Whatever the effect of THP on human health, it becomes important to establish its actual presence not only in RSV-containing food and beverages but even in cosmetics that, by their nature, are subject to UV radiation.
This is the post number 100. One hundred of weekends that I spend writing, reading, illustrating, editing and publishing the posts. The time that I spent do it is just part of the time I stole to the family, special to my youngest daughter, so today I decided to involve her in this project. The illustration is her authorship.
Wine metabolome results from a complex process, involving grapes, yeast, bacteria, terroir effects and its ageing in wooden barrels. Wine metabolome fingerprint tells the story of its origin, production and quality. Its characterization is of paramount importance for quality control, authenticity and quality improvement. Wine metabolome characterization remains one the greatest challenges of analytical chemistry and biochemistry that challenges all conventional approaches to metabolomics.
The biomolecular characterization of foods and beverages represent nowadays an intriguing task for the scientific community. While nonvolatile compounds of a wine, e.g. polysaccharides, organic acids, mineral salts and polyphenols, have a great impact on the mouthfeel with acidity and salinity perceptions and astringency, the volatile component is the main responsible of wine aroma that contributes to the peculiar recognizability of a vine. Food aroma is the result of the complex interaction of small volatile molecules and odor receptors and, although its perception might be affected by subjectivity, it is considered as the first step in quality assessment.
Wine alcohol content can now be measured using membrane contactors through the measurement of the trans-membrane flux. This approach involves a flat cell module equipped with a commercial polypropylene membrane. One membrane side of the membrane is in contact with wine and the other one is under vacuum. A preliminary experiment was carried out using hydro-alcoholic solutions with final ethanol contents of 5, 10 and 20% v/v. A correlation line was obtained between the trans-membrane flux and the ethanol content of the feed. Then this approach was applied to measure trans-membrane fluxes of commercial white and rosé wines (both at 10.5% v/v), results were reported on the correlation line, so that to compare the real alcohol content with the predicted one. This post describes the results obtained and discuss the utility of this method to measure wine alcohol content.