malvidin-3-glucoside and caffeic-acid

The copigmentation effects of polyphenol with different structures vary greatly. Therefore, the aim of this study is to investigate possible interactions in red wine model solutions between oenin and three phenolic compounds: danshensu, caffeic acid and rosmarinic acid. Our results show that the copigmentation of rosmarinic acid is the strongest among the compounds tested. The colourimetric parameters indicate that colour intensity becomes enhanced with increasing concentration of these copigments, leading to darker and more vivid bluish colours. Thermodynamic and quantum chemical investigations are performed to interpret the absorption properties in the visible range. Fluorescence spectroscopy confirms the interaction between caffeic acid and oenin, while FTIR spectroscopic results further suggest a role for hydrogen bonds in the overall process. To our knowledge, this is the first experimentally corroborated direct evidence of hydrogen bonds in copigmentation.

Topics: Anthocyanins; Caffeic Acids; Cinnamates; Color; Depsides; Lactates; Rosmarinic Acid; Spectrometry, Fluorescence; Spectroscopy, Fourier Transform Infrared; Thermodynamics; Wine

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.

Topics: Anthocyanins; Caffeic Acids; Glucosides; Time Factors; Vitis; Wine

Intermolecular copigmentation reactions are significantly responsible for the manifold color expression of fruits, berries, and their products. These reactions were investigated with five anthocyanins and five phenolic acids acting as copigments. The stability of the pigment-copigment complexes formed was studied during a storage period of 6 months. The study was conducted using a UV-visible spectrophotometer to monitor the hyperchromic effect and the bathochromic shift of the complexes. The greatest copigmentation reactions took place in malvidin 3-glucoside solutions. The strongest copigments for all anthocyanins were ferulic and rosmarinic acids. The immediate reaction of rosmarinic acid with malvidin 3-glucoside resulted in the biggest bathochromic shift (19 nm) and the strongest hyperchromic effect, increasing the color intensity by 260%. The color induced by rosmarinic acid was not very stable. The color intensity of pelargonidin 3-glucoside increased greatly throughout the storage period with the addition of ferulic and caffeic acids.

Topics: Anthocyanins; Caffeic Acids; Cinnamates; Color; Coumaric Acids; Depsides; Drug Stability; Food Preservation; Glucosides; Hydroxybenzoates; Pigments, Biological; Rosmarinic Acid; Solutions; Time Factors