Pop the cork and watch the delicious liquid glug out of the bottle into your glass. Most never think about the science. It is just fermented grape juice, right? Well yeah, mostly, but as long as we’ve been making wine, we’ve been utilizing the best available technology to make it taste better. Fast forward a thousand years or so and winemakers now consistently make myriad additions to the wine on its journey from grape to glass. At varying times in the production process, these additions preserve, adjust, and enrich the finished wine to be at its best. However, there are those that question their use and some winemakers that go so far as to abstain from any additions at all. Knowledge is ultimately power, and a deeper understanding of what is used will enable you to decide for yourself. So what else is in that wine you’re pouring and why?
1.Egg Whites, Ox Blood, and Sturgeon Bladder
A bit of a shock to those unfamiliar with their use, all of these additions are proteins derived from myriad sources used simply to fine or clarify the dissolved solids out of the finished wine in order to obtain a more clear and stable finished product. Some of these agents also remove off-flavors, prevent the wine from browning and minimize harsh tannins. Ox blood is the most steeped in history, used for hundreds of years in Europe until its use was banned in the EU following the mad cow disease scare of the 90’s. Albumin, the useful protein in blood, is all so found in the common egg white which is still commonly used for the same reason. More filtering agents are Isinglass (derived from the bladders of sturgeon), gelatin(sourced from pork bellies), chitosan (derived from shellfish), protease (sourced from cow stomach and pancreas), and bentonite (volcanic clay). Most recently, the issue of allergies has become common and while almost every molecule of these fining agents is removed from the finished wine, some labels have begun naming anything used in production that could be an problem.
2.Sugar & Acid
You may have heard of these two before. Sugar and/or acid are added to most wine on the market. Adding sugar is called "chaptalization". Adding acid is called, naturally enough, "acidifying". Hypothetically a winemaker will use one or the other; adding sugar in cold climates where the grapes reach ripeness but with low levels of sugar. Conversely, acidification occurs in hot climes where the grapes develop plenty of sweetness but not enough acid, which results in wine that is flabby and boring. The sugar that is added is simple sucrose easily available at the grocery store while the acid used is tartaric. While each country regulates these additions, the true amounts of either is often kept quite "hush hush" and questioning a winemaker about his or her usage may lead to a much abbreviated conversation or tasting.
Oxygen is 20% of our atmosphere and the gas we depend on for survival. We often underestimate or are simply unaware of the destructive nature of oxygen. The current life on this planet evolved in differing directions for just this reason; with some life hiding deep in the ocean or others, like humans, adapting to use it as fuel and mitigating its negatives by utilizing antioxidants. In the case of wine making, oxygen is prohibited from interfering at almost every stage of production to protect fruity flavors and freshness. Yet despite its negative characteristics, its judicial use can actually benefit the wine at certain points of production. Primarily, oxygen is added to the juice before yeast inoculation to help give the yeast a boost, allowing them to build populations necessary for a healthy fermentation, though it is used at other times as well. In fact, wines made totally anemically (without any oxygen) often show flaws, "off smells" of rotten eggs are a perfect example.
The most common use of oxygen for the consumer is when they open the bottle. Simply pouring the wine into a glass begins the process of oxidation that will eventually lead to the wine becoming vinegar. In the short term though, this oxidation allows the wine to become more expressive and many consumers enjoy tasting this transformation. In many higher alcohol, tannic wines, oxidation is encouraged though decanting or pouring the wine through a vinturi, though one should be cautious with older wines as they will transition into something undrinkable much quicker.
4.D.A.P. (Diammonium Phosphate)
In order to ferment all (or most) of the sugar out of the juice without the risk of funky phenols (smells), the yeast needs one nutrient above all else; Nitrogen. DAP, or Diammonium Phosphate is added to supplement this nitrogen and invigorate the yeast so your wine doesn’t smell rotten. It also serves to strengthen the yeast to ferment the wine without getting stuck (see below). It is also used elsewhere as a fertilizer, fire retardant and nicotine enhancer in cigarettes.
While it seems silly to dilute all the flavors that are developed in the vineyard, water is sometimes necessary to make a dry wine. Modern preference for opulent, fruity, high alcohol wines has had the effect of encouraging viticulturists to allow their fruit to ripen until it has sugar levels with potential alcohol levels of almost 20%. There is no yeast that can survive to convert sugar at alcohol levels this high, so winemakers commonly add water to bring the potential alcohol down to a level that their chosen or natural yeasts can successfully ferment the sugar to the desired level of dryness. If not, the fermentations will simply get “stuck” with high levels of alcohol and sugar. When adding water before fermentation, its is important to add acid and tannin to the water, matching the PH of the must (grape juice and skins),before its addition. This process is not relegated to cheap plonk, but is often utilized by winemakers producing the most lauded wines available. Trends in some regions have resulted in wines with an ABV of upwards of 17% and over 5 g/L of residual sugar.
In the pickup game of additions, sulphur dioxide, or SO2, is the first choice for most winemakers. As the primary defense against the ravages of oxygen, SO2 has been added since the Roman days. Back then, they burned sulfur candles in the barrels before filling them to defend against bacteria that would spoil the wine. Today, sulfur is added at most stages of the production cycle in order to protect the wine from the ravages of oxygen and to protect it from undesirable yeasts like Brettanomyces (produces a barnyard "funky" smell) and bacteria that leads to volatile acidity (vinegar). Many advocates of its use believe wine destined to be aged for any length of time should have the protection of sulphur.
Sulphur has fallen into the same category as MSG and gluten as the culprit for negative health symptoms. Though, just like gluten, there are people with a severe, albeit rare, allergy. Many countries now require sulphur use to be displayed on the label. Though naturally present in all wine, the majority of sulfur in wine is due to its addition in the wine making process. It is also commonly used in the production of many other foodstuffs including fruit juice, dried fruit, prepared foods, and sausage. Do not fear the sulphites!
Ultimately, its important to remember that the additives mentioned here are just the tip of the iceberg of available and perfectly legal chemicals, enzymes, and enhancing agents used in the production of wine. While many may react strongly at this realization, remember that these same substances are used to make all sorts of food and beverage products, many using much higher amounts. Education serves to allow the consumer to spend their hard earned dollars on products that reflect their values and many winemakers have reacted by becoming much more transparent about the additions they use. Regardless of your opinion, at least you’ll sound knowledgeable when it comes up at a dinner party.