MAKING WINE - Alcohol science part two
Making of wine is one of the earliest chemical processes used in food, discovered most probably by chance, at least 9,000 years ago in the earliest civilizations. The first wines were all made from red grapes, but in later times, the Egyptians managed to get a white grape that has spontaneously mutated from the red color. Already at this stage of wine making, the good practice of aging the wine in air-tight mud-sealed wine amphoras was invented. Only at a later time, during the Roman empire, people discovered wood barrel aging that allowed the wine to pick up some flavors from the wood and further enhance the enjoyment of the drink.
The start produce to make wine is the grape. This is the main flavor-giver, with the flavor-creators being yeasts and other microbes, as well as the wood containers in which the wine is stored. The color of the grape is provided by the anthocyanin pigments (red grapes) and flavonols (white grapes only). The main compound that the yeast consume is the sugar, but the grapes also contain some acidic compounds like tartaric acid (inhibit growth of many fowl microbes), together with tannins – the phenolic molecules that are “scraping” on the tongue when you drink red wine. Besides these basic compounds, we also need some flavor in the grape to get a good wine. However, many aromatic molecules are not released until the yeasts cut them off from other molecules (often sugars), and so the flavor of the wine develops during yeast fermentation.
There are several thousands of grape varieties in the world, and even among the famous ones, e.g. Cabernet Sauvignon, Chardonnay, there is a wide range of differently tasting grapes. All this cocktail simply emanated during the ages of cultivating grapes, by spontaneous mutations (sort of microevolution), by moving the grapevines from one place to another, or by simply breeding the grape once a pleasant variety popped up. Some of the grapes are good for making wines that develop deeper complex flavor with age, these including Cabernet Sauvignon, Pinot Noir (red grapes) and Chardonnay or Riesling (white grapes) – to mention the most popular ones. If you travel to some of the wine-making countries you will encounter many local varieties of the grapes that you may like and stuff your car with some bottles of these. A really nice trip idea I think – going around the small farms, tasting their wines, and purchasing your own collection of these goodies.
Much of the flavor of the grape depends on how it is cultivated. You cannot simply grow the grapes. To get a well-balanced content of sugar, acids, and aromas the grape needs sufficient sun, water, and minerals from the soil. On the other hand, it cannot have too much of these either: excessive sun will make the grape very sweet, which the yeasts will manage to turn into lots of alcohol, but the aroma will suffer. Too much water and minerals will induce growth of many leaves on the grapevines – these will in turn shield the fruits from the sun and render them bad or strange-tasting. Another factor that influences the taste of the grape is the soil in which it grows with all its details and microclimate (terroir). In any case, the optimal condition of a wine grape is for it to be fully ripened, with enough sugar and aroma to make a great wine. This largely depends on weather of course, and this is why people can be so picky about the years during which the wine in question was produced. Some years in certain regions are worse for the grape agriculture, and some years are better.