In Banyuls , winemakers use various methods to " bake " their wines to encourage deep raisin colors . Some winemakers utilize a solera system of transporting the wine among different size barrels of various ages that are left out in the sun to warm . Others will put the wine in large glass jars to expose it to direct sunlight . In addition to the dark color , the resulting wines often have a nutty , rancid taste called rancio . In the Banyuls Grand Cru AOC the wine is required to be aged in wood barrels for two and a half years .