This post reports the results of study where fermentations were performed using simulated grape juice supplemented with terpene glycosides (TGs), extracted from Vitis vinifera L. Meili, and phenolic acids (gallic acid or p-coumaric acid). Free terpenes were detected using solid phase microextraction-gas chromatography-mass spectrometry (SPME-GC–MS) every day during the fermentation, and the aromas of final wines were evaluated by panelists. Results showed that phenolic acids remarkably inhibited TG hydrolysis and free terpene volatilization, and affected wine aroma perception. These findings indicate that the matrix effect of phenolic acids can effectively control the release and modulate the global feature of wine aromas. See all at: http://science-and-wine.com/
Polyphenols are a diverse group of compounds of utter importance to wine quality. Current understanding of the polyphenolic composition in wine is well elaborated, however, recent studies continuously report novel findings involving them. It is evident that synergistic approaches between emerging analytical platforms in combination with advanced multivariate data analysis will be considered the spearheads toward fraud detection and the provision of authentic wines.
This post describes a tandem absorbance and fluorescence detection following liquid chromatography (LC-DAD-FLD) method for the determination of 32 phenolic compounds (PCs) in winemaking industry derived products. The applicability of the method was verified by the suitable quantification of analytes in complex samples of wine, bunch stem and grape cane extracts. The developed LC-DAD-FLD approach is highly recommended for processing large sets of samples in routine quality control of extracts or during characterization studies.
This post is about a study that delivers a comprehensive flavonoid fingerprint profile, physiochemical and external color characterization of Plavac Mali grapes through four harvest dates at two distinct vineyards (Split and Zadar) in the Eastern Adriatic region. Results show that berries of extended harvest dates underwent colorimetric improvements, trough decrease in CIELab color space parameters a* (reed/green), b* (yellow/blue), L* (lightness (0, black; 100 white)) and C (chroma, relative saturation) characteristics and increase in skin color index for red grapes. In conclusion, the extended harvest date promotes flavonoid composition, and improves the quality of Plavac Mali grape berries.
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.