Effect of different cofactors on the color of red wine
You saw how the addition to a fermentation of the cofactor caffeic acid increased red wine color. These authors go a bit further and study the effect of several cofactors, on several varieties.
Find the full text at: http://pubs.acs.org/cgi-bin/article.cgi/jafcau/2005/53/i21/pdf/jf051005o.pdf