Cabernet Sauvignon Aging Stability Altered by Microoxygenation

Abstract

Microoxygenation (MOx) is used to reduce vegetal aroma and improve color by converting anthocyanins to stable pigments. A Cabernet Sauvignon wine treated with different levels of sulfur dioxide (SO₂) and glutathione (GSH) was microoxygenated, bottled with equivalent free SO₂ levels, and stored under controlled conditions for 28 months. After bottle aging, the MOx-treated wines, particularly those treated with relatively low levels of SO₂ and GSH during MOx, showed much more acetaldehyde and stable polymeric pigments and very stable color compared to wines without MOx treatment. MOx-treated wines also lost more SO₂ during aging. Higher SO₂ during treatments with or without MOx resulted in more protein-reactive tannins after aging, suggesting implications for wine mouthfeel. The addition of SO₂ and, to a lesser extent, GSH before MOx, was associated with slowed wine oxidation reactions during aging and reduced color stability, leading to greater color loss. These results show that MOx prior to bottling has a dramatic effect on the evolution of wine during aging. The MOx-treated wines had a more stable color, but they also lost SO₂ protection more quickly, and thus may need more SO₂ before bottling to ensure comparable stability during aging. These results suggest that MOx treatment removes some preservative factors in new wine, possibly phenolics that act as stabilizers.