why do wine thicken

The Deep Dive

The thickening of wine is a fascinating interplay of chemistry and biology. At its core, wine contains tartaric acid, one of the primary acids found in grapes. During fermentation and aging, this acid can combine with potassium naturally present in the wine to form potassium bitartrate, commonly known as cream of tartar. When wine is chilled, especially below its freezing point, or when it undergoes temperature fluctuations, these tartrate crystals precipitate out of solution. This process, called tartrate crystallization, is accelerated by factors such as low pH, high alcohol content, and the presence of other ions. Winemakers often induce this through cold stabilization, where wine is cooled to near-freezing temperatures to encourage crystal formation before bottling, preventing unsightly sediment in the final product. Additionally, other compounds like proteins and polysaccharides can contribute to viscosity, but tartrates are the primary culprit for noticeable thickening. Over time, oxidative processes or microbial activity might alter wine's texture, but the crystalline sediment is the most common and benign cause. Understanding this helps in appreciating the delicate balance of acids and minerals that define a wine's character and stability.

Why It Matters

Knowing why wine thickens is crucial for both winemakers and consumers. For producers, managing tartrate crystallization ensures product consistency and prevents consumer complaints about sediment, which is often mistaken for spoilage. Techniques like cold stabilization are standard in the industry to maintain clarity and mouthfeel. For enthusiasts, recognizing tartrate crystals as harmless allows for a deeper appreciation of wine's natural processes. This knowledge also aids in proper storage and serving; for instance, chilling wine slightly can enhance flavors but might cause temporary thickening. Ultimately, it demystifies a common occurrence, turning potential concerns into an understanding of wine's complex chemistry, enhancing the overall experience.

Common Misconceptions

A common myth is that wine thickening or sediment indicates a faulty or spoiled bottle. In reality, tartrate crystals are entirely harmless and often a sign of a well-made, minimally processed wine. They do not affect flavor negatively and can be easily removed by decanting. Another misconception is that thickening is always due to additives or manipulation; however, it's a natural chemical reaction inherent to wine composition. Some believe that only cheap wines develop crystals, but even premium wines can exhibit this, especially if not cold-stabilized. Correcting these myths helps consumers make informed choices and reduces unnecessary waste.

Fun Facts

• Tartrate crystals in wine are sometimes romantically referred to as 'wine diamonds' by connoisseurs.
• The process of cold stabilization to remove tartrates was pioneered in the 19th century and is now a standard practice in modern wineries.