What do you do when you’re snuggled in a comfortable seat with unlimited movies and a hearty prepackaged meal on your hands?

Well, I decided to order some wine and start binging, because for the next 13 hours, I had nothing else to do but wait for my flight to touch down in San Francisco.

I was travelling from Sydney for a work event and I couldn’t have asked for a better meal or hospitality. Unlike most people’s claims, I’ve always thought airplane food quite good. Despite being a picky vegan, I’ve managed to find the meals palatable and enjoyable.

So of course I was going to complement it with wine. A white sauvignon blanc, please, I asked. And with a wide smile, the cabin staff member handed me a two-serve bottle of wine. Settling myself in a more comfortable position, I glanced at the label as I always did.

“Made with the aid of egg whites and traces may remain.”

My heart stopped in mid air. Egg whites in wine? Wasn’t that illegal? Why would anyone combine grape juice with eggs? What abomination?

Questions bombarded my already heavy head. Everything I knew and loved about wine came to a sudden halt and I started questioning my entire affliction to the grape nectar. I started searching my brain for any information I’d heard or read of that justified or even explained the use of dairy in winemaking. Alas, not even my memories of winery visits and tastings revealed anything to shed light on this phenomenon.

I waited for what seemed like an eternity for the cabin member to pass my seat again. I returned the unopened white and asked for a red instead—a syrah, this time. With another, judgement sans smile, he handed me a bottle, twisting the cap open as if to indicate I couldn’t change my mind anymore.

“Made with the aid of egg whites and milk and traces may remain.”

I drank the wine. I was having bad headache and it wasn’t the time to research or argue with the flight crew about my dietary preferences in alcohol. In a moment of deep sadness, guilt, and weakness, I drowned the wine and slept like a baby for the next 12 hours.

Three days later, still battling jet lag, I looked it up online. According to some articles, winemakers use egg whites, milk, and even fish bones to help separate the natural sediments in wine. Grape starches, peels, and other natural and goopy stuff that occur during the ageing process stick to these dairy products and sink to the bottom of the barrel. This makes it easier for winemakers to filter those sediments from the wine that goes into bottling. The entire process is called fining—refining the wine from the undesirable lumpiness of the residue from crushed grapes.

So there we have it—although the eggs and milk don’t leave any trace in the actual wine that goes into our bottles and glasses, dairy is an ancient part of the wine process.

What’s interesting though, is that most modern winemakers have found vegetarian alternatives like seaweed and volcanic clay for their fining processes. And when they use dairy, they say so in their labels—it’s even required by law in Australia and New Zealand.

Ha. And I used to think “vegan wines” was just a modern marketing stunt!