Polyphenols in wine
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Polyphenols are compounds contained into grape skin whose presence in wine depends from the winemaking technique. Polyphenols content in must, and therefore in wine, is determined by the duration of the contact among must and grape skin. Phenolic compounds coming from grapes have an essential role in characterizing the different red wines since they are responsible of their colour but they also influence their smell and moreover their taste. Following their different polyphenols content, the different wines can be classified as white, rosè, red, dark red, etc. From the nutritional and quality point of view, phenolic content, together with the chromatic profile of wine, gives important to judge a wine.
Instrument
FoodLabWine
Reagents
R (pre-filled in cuvette): alcoholic mixture with potash, phenolphthalein derivative
Test method
Test type: End Point
Colour reading at 630 nm
Test time: 5 minutes
Calibration can be performed by aligning the test to reference values
Test principle
he polyphenols, when in contact with a coloured complex in an alcohol solution, become oxidized and discolours. This decrease in colour, measured at 630 nm, is directly proportional to the concentration of polyphenols in the sample, expressed in mg/L of gallic acid.
Sample
Wine as is.
