Brix very similarly to sucrose with respect to specific gravity as a function of concentration, or compounds which are present in small amounts (minerals, hop acids in wort, tannins, acids in must). In any case, even if °Bx are not representative of the exact amount of sugar in a must or fruit juice they can be used for comparison of relative sugar content. As specific gravity was the basis for the Balling, Brix and Plato tables, dissolved sugar content was originally estimated by measurement of specific gravity using a hydrometer or pycnometer. In modern times, hydrometers are still widely used, but
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