Carbon dioxide. Proteins. Beer foam. And more science about how beer makes yummy crusts.
There are many reasons why beer-battered foods like fish and chips are yummier. One of them is the carbon dioxide bubbles in beer stretch the batter to make the crust fluffier while providing additional insulation to prevent overcooking.
The carbon dioxide bubbles would, however, be unable to do all this if they burst as soon as they are formed. They would neither rise to stretch the batter nor provide much insulation.
The reason they take a while to pop has to do with a phenomena we have all seen: the beer foam in a glass of beer. Beer foam forms and dissipates slowly because the carbon dioxide bubbles in it are coated with a layer of proteins that slow down the rate of bursting.
Where do the proteins come from? They come from the beer too, originating from the barley that many beers are made from. Specifically, Professor Karl J. Siebert from Cornell University has found that one particular protein, lipid transfer protein 1 (LTP1), seems to show “greater involvement” in the formation of beer foam.
What does LTP1 do? LTP1 has high hydrophobicity, meaning it is not attracted to water. (One way to visualise hydrophobicity is to look at the droplets of dew on leaves — the leaf surface is hydrophobic).
In fact, LTP1 tries very hard to stay away from water. (It’s beginning to sound like some teenage crush.) LTP1 does exactly that by catching onto the bubbles of carbon dioxide, thus coating each bubble with a layer of protein.
These protein-coated carbon dioxide bubbles then rise to the top of the beer, forming beer foam. The coat slows down the speed at which the bubbles burst, giving the foam structure while ensuring it sits around at the top for a while.
This process is how the carbon dioxide bubbles help to make beer battered fish yummier. The bubbles too are coated by the LTP1 found in the same beer. The protein coat prevents the bubbles from bursting, giving it time to rise through the batter to make the crust fluffier, and to act as insulators against overcooking.
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