If aeration is required in order to enhance aromatic complexity, exposing the must to oxygen at the beginning of the fermentation is much less risky and more effective then at the end, when the yeast growth factors are depleted. Musts from rotted vintages should be aerated as little as possible due to the presence of oxidative enzymes in solution. Red musts can be aerated to a greater extent to increase the rate of fermentation (Morgan et al., 2006).