The Chemistry of Wine

In Death in the Afternoon, Hemingway writes that “wine is one of the most civilized things in the world and one of the most natural things of the world that has been brought to the greatest perfection, and it offers a greater range for enjoyment and appreciation than, possibly, any other purely sensory thing.” What this eminent novelist and renown oenophile also knew was that not all wines are created equal. The scientists at ISI also know this to be true and realize the importance of empirical methods to make sure devoted vintners are able to produce the best quality of wine and that conscientious consumers have all the information they need to make the best choices for their own health and particular palate.

It is well known that selecting the optimal moment of ripeness and harvest is considered to be the most crucial decision in winemaking. Traditionally, winemakers have measured the sugar, acid and pH levels of the grapes to help them decide when this moment has arrived. However, there has been a shift in recent years to using modern techniques to measure the level and ripeness of tannins, the formation of polyphenols and the development of flavor precursors. The level of tannins in wine fluctuates greatly and is one of the most important factors giving the different variety of wines their distinctive flavor profile. Having unripe tannins present in the fermentation process can ruin a batch of wine.

Much less obvious to the wine producer and consumer is the exact polyphenol level in the finished product. Polyphenols are the antioxidants that have made wine famous for its health benefits. They have been purported to help prevent many health problems, including cancer, cardiovascular disease, diabetes and neurodegenerative diseases. It is difficult to avoid the news that wine can be an important part of a healthy lifestyle and many shoppers are looking to get the most from their bottle purchase. The ability to scientifically test for polyphenol levels gives producers the means to display this information on their labels and attract the customer who is particularly concerned with maximizing the health benefit of wine.

Another concern for many consumers is the fact that common allergens such as sulfites, milk, gluten and egg can be found in wine. The majority of vintage wines contain added sulfites without declaring them on the label. Also, as a part of the fining produce, agents containing milk and egg whites are often used. Furthermore, the longstanding practice of aging wine in barrels with a flour-based paste to smooth the joints on the barrel heads can introduce levels of gluten to wine that may represent a risk for individuals suffering from food sensitivity and allergy. Starting with Australia over a decade ago and more recently the EU and Canada, governments are now requiring wine labels to indicate if their product may contain allergens. There are standard test available to determine whether or not a wine actually contains traces of allergens and at what level. This helps wine makers to be able to advertise their product as being free of gluten or low in other irritants including sulfites.

The scientists at ISI believe that it is important to identify critical compounds in grapes as well as possible additives in order to calculate attributes known to be important to consumer preferences. More and more wine drinkers are concerned about both maximizing the health benefits of wine as well as avoiding ingredients that they don’t desire. This requires the testing of grapes and wine to both ensure the finest quality and detail the levels of both desirable and undesirable components. In so doing, one may discover the specific influences that cultivar, climate and technologies can have on wine production. All of this can make sure that customers have the information they need to make the wine purchases they desire. After all, as Papa Hemingway also taught us, “My only regret in life is that I did not drink more wine.”