Casse

Casse meaning in wine

Casse is a wine defect characterized by the formation of an unwanted haze or cloudiness that develops when unstable compounds precipitate out of solution. This phenomenon occurs most commonly due to protein instability, where naturally occurring proteins in wine coagulate and form visible particles, particularly when exposed to temperature fluctuations or during storage. Metal casse represents another form, typically caused by excessive copper levels (often from previous copper sulfate treatments used to remove hydrogen sulfide) or iron contamination from winemaking equipment. Copper casse manifests as a reddish-brown haze, while iron casse appears as a bluish or whitish cloudiness. Protein casse is more prevalent in white wines, as they retain higher protein levels than reds, which lose most proteins during fermentation and maceration with grape skins. Prevention involves protein stability testing using heat or tannin treatments, and bentonite fining to remove excess proteins before bottling. Metal casse prevention requires careful monitoring of copper and iron levels, typically keeping copper below 0.5 mg/L and iron below 5-10 mg/L. While casse doesn’t necessarily affect taste, it creates an unappealing appearance that renders wine commercially unacceptable, making pre-bottling correction essential for quality winemaking.