Bottleshock...Nobody Really Knows

Over a year ago, a brilliant, wine loving friend who moonlights as a neuroscience PhD, asked me to collaborate on a piece about bottle shock. Since I had nothing intelligent to contribute, I conveniently “forgot” he asked. “Bottle shock…yeah, I saw the movie. Nobody really knows,” didn’t quite cut it.

Fifteen months later, Wine Business Monthly has shamed me. The July cover announces “The Mystery of Bottle Shock.” Superimposed is a cartoon of a wine bottle wired with electric circuitry, emitting lightning from the headspace. It’s prescient too since we bottle the 2011 pinots next month. And informative - each expert interviewed for the article offers a different explanation. Turns out, “nobody really knows” was more accurate than shady.

WBM discusses bottle shock with everyone from long time winemakers to UC Davis academics to top industry personnel. Nearly every theory indicts oxygen as a culprit. Oxygen accelerates oxidation, alters redox potential, messes with sulfur, and is a precursor to reactive peroxide. Also implicated: filtration (all types), bottling lines, last minute blending, 11th hour sulfur dumps, and any/all wine transfers and transports. This catch-all umbrella pretty well covers every post-fermentation, winemaking operation. It also means anything I write is correct- at least a little.

Some theories sound simple and seem plausible, like Bo Barrett’s hypothesis (FYI - he’s the protagonist in the BottleShock movie). Wine inside a barrel is in equilibrium with oxygen that slowly seeps through the wood. When it’s transferred to an impermeable glass bottle, that oxygen balance changes. Dr. Andy Waterhouse (UC Davis) carries Bo’s logic to its biochemical conclusion. The introduction of oxygen converts ethanol (alcohol) to aldehydes (smelly stuff). At a critical threshold, those aldehydes impact aromatics, diminish fruity character or dampen varietal charm. But since aldehydes are themselves reactive, their impact is temporary. Over time, they bind up with other wine chemicals, and you can’t detect them anymore. Bottle shock effectively “disappears.” But now consider the confounding impact of our various pre-bottling and bottling practices. We winemakers add a good dose of sulfur at bottling, which mops up stinky aldehydes too. Does that mean sulfur helps fix bottle shock? Or would it spontaneously resolve anyway? How come others blame sulfur additions for “a big influence on what we perceive as bottle shock?” (WBM, p 22)

Both filtration and bottling are singled out as potential sites of oxygen over exposure. But filtration gets an especially bad rap as a dual offender. It both exposes wine to unwanted oxygen and mucks with the “colloidal matrix.” When considering the colloid theory, the window screen analogy works best. Imagine pushing the wine through a screen with tiny, tiny microscopic holes. Compounds (of any type) that are too big to flow through the interstices are retained by the screen. In theory, removing these compounds can alter the wine. But again, this is temporary. As tannins and colloids reconfigure into longer compounds, the “bottle shock” resolves. While filtration may sound disruptive, rigorous academic concludes it neither disrupts the polysaccharide matrix nor altering sensory properties. My UC Davis coursework and textbook also debunk the myth that filtration “permanently strips” wine of varietal character and aromatics.

Dr. Roger Boulton’s explanation is kind of an outlier. He wrote the UC Davis textbook and is the only expert to implicate peroxide. He blames bottle shock on “a long persistent concentration of peroxide.” According to Boulton, when wine is exposed to oxygen, the direct effects are short lived. But peroxide, a reactive oxygen by product, sticks around. Boulton proposes that it’s really peroxide that dampens varietal character and ignites oxidative damage. But again, the sulfur we winemakers add pre-bottling “masks” the effect. For Boulton, the purported “bottle shock” is residual carry over from prior oxygen pickup. Whether from racking, filtration, or transfers, it all thoroughly predates the actual bottling process.

So what’s my personal experience? Last year, I complained to a fellow winemaking mom that my newly bottled pinots tasted and smelled pretty lipid. “Don’t’ worry. They’ll bounce back,” she reassured me. “They always do.” And of course they did.

This information is excerpted from “The Mystery of Bottle Shock” by Lance Cutler, Wine Business Monthly, July 2012. The full article can be accessed here: