COOKING WITH ALCOHOL - Alcohol science part one
Alcohol is produced from sugar by yeasts, and they do so to defend themselves against other microorganisms that could also thrive in a nutrient-rich environment. This prowess has a lot to do with their low demand of oxygen, at least when it comes to competition for survival. Sure, they like oxygen if they want to proliferate quickly, but when it comes to knocking out other small living things in competition for food, the yeasts spit out alcohol and manage to live – albeit in slow growth – in low oxygen environment. And the yeasts that ferment the alcohol are amazingly resistant to it, they may tolerate up to 20% of the tough stuff, that is the amount in which most life cannot survive. For this reason highly alcoholic drinks can be kept for many years after opening without being rotten and consumed by microbes.
But alcohol is not the only thing the yeasts produce while they ferment, for example, a grape juice. They also contribute to the final flavor of the alcohol drink by making fruity-tasting esters, savory succinic acid, and long-chain alcohols that give that sort of oily feeling in the mouth. At the end of their lives, when the yeast dies, their intracellular enzymes break down the cellular compounds and molecules present in the fermenting liquid, further improving the flavor.
Alcohol, while fully miscible with water, has some special properties that chefs put to use. Firstly, it boils already at 78 C/176 F, which makes it possible to reduce alcoholic content of a food (e.g. when cooking with wine or cognac) and concentrate the flavorful compounds contained in it. Second, you can make a fine flambé with alcohol without burning the food, since all the heat will be dispersed mainly in the water that is all around the flames. Lastly, you can make fun layered drinks by pouring high- alcohol liquid over low-alcohol liquid, since the addition of alcohol (the higher the percentage) will decrease the density of the solution (weight per volume ratio).
One very good thing about alcohol is that it can extract and collect fat-soluble flavor compounds in the food, so a small addition of alcohol, as chefs often do, would improve the taste of the food. The trick is to not get too much of alcohol (it’s not what you want to taste really) and neither to get below 1% of it because then – paradoxically – these fat-soluble flavors will start to quickly evaporate.
Cooking with alcohol can be quite confusing, because it may not evaporate as easily as we expect it to. Indeed, the best method to get rid of almost all alcohol is to cook it for a long time on low heat – for example in a braise. Quick cooking may actually retain around one-third of alcohol, and flambé is the worst method to remove the alcohol as three-fourth of it may remain in the liquid. In short, depending on what cooking technique you use, add a reasonable amount of alcohol – count beforehand how big volume you can add to arrive at 2-4 % final concentration. Alternatively, if you don’t think it will affect the flavor of the dish, make a reduction of an alcoholic drink per se, and then add it to the food – this is especially good in quick cooking.