Oak aged mythology – According to recent research at the Public University of Navarre, wine makers get no benefit to their product from leaving wines to mature in oak casks for more than a year. In fact, chemical analysis showed that levels of aromatics in the wine from the oak casks begin to decrease if the wine is left to mature for too long. Legislation insists that Gran Reserva wines be kept for 18 months, but science shows that this isn’t based on sound chemical principles.