Hunter Valley wine rot), "Greeneria uvicola" (bitter rot) and other fungi from the genera of "Aspergillus, Penicillium" and "Alternaria". Susceptibility of certain wine grape varieties were found to increase as the grapes reached higher Brix sugar levels. Further research in the 2000s, showed that some of the open canopy techniques used to prevent "Botrytis" grey rot may actually promote the development of some of these other types of rot. Ripe rot, in particular, seemed to thrive at the higher ultraviolet B (280–320 nm) light exposure that open canopies allow. To compound the potential problem for Hunter Valley wine growers is that, as of
Phenolic content in wine the vanilla notes in wines that have been aged in oak. Trace amounts of vanillin are found naturally in grapes, but they are most prominent in the lignin structure of oak barrels. Newer barrels will impart more vanillin, with the concentration present decreasing with each subsequent usage. Oak barrel will add compounds such as vanillin and hydrolysable tannins (ellagitannins). The hydrolyzable tannins present in oak are derived from lignin structures in the wood. They help protect the wine from oxidation and reduction. 4-Ethylphenol and 4-ethylguaiacol are produced during ageing of red wine in oak barrels that are infected by brettanomyces