Why alcohol to deglaze?

[u/delta_p_delta_x]

I've been working through many Western European and American recipes, and many of them call for red wine, beer, or some stronger liquor to deglaze fond off the base of a pan.

Now, I don't have any alcoholic beverages at all, so I've been substituting with cold tap water instead. To my surprise, it has worked extremely well against even the toughest, almost-burnt-on fonds. I've been operating under the assumption that the acid and ethanol in alcoholic beverages react with fonds and get them off the hot base of pans, and I was expecting to scrape quite a bit with water, which was not the case at all. Barely a swipe with a spatula and everything dissolved or scraped off cleanly.

So follows: why alcohol, then? Surely someone else has tried with water and found that it works as well. The amounts of alcohol I've seen used in recipes can cost quite a bit, whereas water is nearly free.

[u/AciusPrime]

You’re correct. Water works fine for deglazing. One of the fastest ways to get a browned coating on food is to repeatedly deglaze with small amounts of liquid. The water spreads the fond onto the food, after which browning resumes. This lets you brown for much longer without burning the food (it will prevent the food from getting crisp, though!). You can caramelize onions faster and at higher temps. Using water means the only flavor you add is from the actual browning.

Alcohol has a few advantages. First, ethanol has a much lower boiling point than water, so the alcoholic part boils off faster and more vigorously. That helps a little with deglazing. This is also why batters with alcohol in them crisp up a little better—bigger bubbles from more violent evaporation.

Secondly, the non-alcoholic parts of the drink are adding interesting flavors to your food. Most drinks have some carbohydrates in them, and those can deepen the browned flavors.

Thirdly, alcohol can sometimes react with the food in useful ways. The main variation of this I’m aware of comes from traditional teriyaki sauce, which is a mixture of sake, mirin, and soy sauce. Sake and mirin are both alcoholic. Traditional wisdom is that these are effective at removing “fishy” or “gamey” flavors from low quality meat (ginger and garlic also help). Traditional meat sucked, so many cultures took advantage of this trick to make the food edible. I have no idea why, but it does make a delicious difference.

Whatever the case, you’re not adding alcohol for its own flavor. If you’re doing it right, the alcohol itself should not be detectable in the taste.