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In red wine, up to 90% of the wine's phenolic content falls under the classification of flavonoids. These phenols, mainly derived from the stems, seeds and skins are often leached out of the grape during the maceration period of winemaking. The amount of phenols leached is known as extraction.
280 nm 45 min LC chromatogram of a red wine, showing mainly phenolic compounds. Wine is a complex mixture of chemical compounds in a hydro-alcoholic solution with a pH around 4. The chemistry of wine and its resultant quality depend on achieving a balance between three aspects of the berries used to make the wine: their sugar content, acidity ...
The grape reaction product (GRP, GRP1 or 2-S- glutathionyl caftaric acid [1]) is a phenolic compound explaining the disappearance of caftaric acid from grape must during processing. [2] It is also found in aged red wines. [3] Its enzymatic production by polyphenol oxidase is important in limiting the browning of musts, [4] especially in white ...
The major acids in wine are tartaric and malic acid with citric and succinic acids playing a small role. The titratable acidity or "TA" (also referred to as "total acidity") is the measure of the tartaric acid in the grapes. This is the most abundant acid and also the one acid that has the most pronounced and long lasting impact on the taste of ...
The three main acids found in wine are tartaric acid, malic acid and lactic acid. The first two come from the grapes and the third from Malolactic fermentation which often occurs in the winemaking process. Active acidity The concentration of acids in the wine. Used to gauge the "total acidity" in the wine. Measured using the pH scale.
The aging of wine is potentially able to improve the quality of wine. This distinguishes wine from most other consumable goods. While wine is perishable and capable of deteriorating, complex chemical reactions involving a wine's sugars, acids and phenolic compounds (such as tannins) can alter the aroma, color, mouthfeel and taste of the wine in ...
In winemaking, clarification and stabilization are the processes by which insoluble matter suspended in the wine is removed before bottling. This matter may include dead yeast cells (lees), bacteria, tartrates, proteins, pectins, various tannins and other phenolic compounds, as well as pieces of grape skin, pulp, stems and gums. [1]
Fischer–Speier esterification. Fischer esterification or Fischer–Speier esterification is a special type of esterification by refluxing a carboxylic acid and an alcohol in the presence of an acid catalyst. The reaction was first described by Emil Fischer and Arthur Speier in 1895. [1] Most carboxylic acids are suitable for the reaction, but ...