Bárbara TORRES-ROCHERA, Ignacio GARCÍA-ESTÉVEZ, María Teresa ESCRIBANO-BAILÓN
Department of Analytical Chemistry, Nutrition and Food Sciences, Universidad de Salamanca, Spain
Email contact: barbara.torres[@]usal.es
AIM: The objective of this work was to perform a colorimetric study of the copigmentation between malvidin-3-O-glucoside, one of the main anthocyanins in red wines, and different wine phenolic compounds and polysaccharides. The present work also aimed to study the stabilization effect on the flavylium cation due to the copigmentation interactions with these compounds.
METHODS: Copigmentation was studied in model systems containing malvidin-3-O-glucoside and different copigments, including flavonols, flavanols, hydroxycinnamic and hydroxybenzoic acids and also polysaccharides at two pH values. The stability of the flavylium cation (25 ºC for 5 weeks) was assessed by HPLC-DAD in an acid medium whereas the study of copigmentation and its relevance on color was carried out at wine like pH (pH 3.6) by differential colorimetry using CIELAB parameters calculated from the whole visible spectra.
RESULTS: Important changes in the CIELAB parameters of the model systems were observed depending on the phenolic compound assayed as copigment, which could point out differences on the copigmentation interactions established. In the case of polysaccharides, it has been observed that they could play a role on the copigmentation effect. Moreover, copigmentation reactions seem to exert an influence on the flavylium cation stability by stabilizating the flavylium concentration during the length of the study or favoring the formation of anthocyanin-derived pigments.
CONCLUSIONS: Color changes and stability of the flavylium cation due to copigmentation phenomenon between anthocyanin and phenolic compounds and/or polysaccharides can be related to the copigment structure.