Investigations on anthocyanins in wines from Vitis vinifera cv. pinotage: factors influencing the formation of pinotin A and its correlation with wine age.
Pinotage red wines were found to contain a reaction product of malvidin 3-glucoside and caffeic acid, the so-called pinotin A. A total of 50 Pinotage wines from the vintages 1996-2002 were analyzed for the content of pinotin A, malvidin 3-glucoside, caffeic acid, and caftaric acid. Statistical analyses were performed to reveal variations in the content of these compounds and to determine the factors that influence pinotin A formation during wine aging. An exponential increase of the concentration of this aging product was observed with prolonged storage time. The most rapid synthesis of pinotin A was observed in 2.5-4 year old wines, although at this age malvidin 3-glucoside is already degraded to a large extent. This phenomenon is explained by the increased ratio of caffeic acid/malvidin 3-glucoside, which strongly favors the formation of pinotin A and makes side reactions less likely. Pinotin A formation proceeds as long as a certain level of malvidin 3-glucoside is maintained in the wines. In wines >5-6 years old degradation or polymerization of pinotin A finally exceeds the rate of its de novo synthesis.
Schwarz
Michael
M
Institute of Food Chemistry, Technical University of Braunschweig, Schleinitzstrasse 20, 38106 Braunschweig, Germany.
Hofmann
Glenn
G
Winterhalter
Peter
P
D000872:Anthocyanins / Q000032:analysis*; D002109:Caffeic Acids / Q000032:analysis; D005960:Glucosides; D013997:Time Factors; D027843:Vitis / Q000737:chemistry*; D014920:Wine / Q000032:analysis*
D000872:Anthocyanins; D002109:Caffeic Acids; D005960:Glucosides; C482620:pinotin A; C458419:malvidin-3-glucoside; C040048:caffeic acid