Dr. David Muhleman

The-Wine-Educator    WINE & SPIRITS EDUCATION AND CONSULTING SERVICES FOR THE CONSUMER AND THE PROFESSIONAL

Dessert wines

I’m faced with a bit of a contradiction; I love dessert wines, but I don’t drink them very often.

I believe I’m like many other wine drinkers and once I have started on the evening’s dinner and wine, I rarely eat dessert, or open a dessert wine. So although I truly enjoy them, unless I make a conscious effort to leave room for dessert, or a dessert wine, I’m usually too full to partake.

There is no simple definition of a dessert wine. In most cases you would assume that any sweet wine could be called a dessert wine, even though not all dessert wines are sweet, and by some definitions they may not even be wine.  There are fortified sherry’s which might be called an “after dinner” (or dessert) wines, which are not sweet (e.g., fino). While other sherry’s (e.g., Pedro Ximenez or PX) are very sweet. While some Moscato dessert wines may only be 5.5% alcohol by volume (abv) which would not even qualify the beverage as “wine” in many parts of the world (i.e., 8% abv is set as the lower limit in some wine producing regions). Finally, many German Rieslings and Alsace wines contain high amounts of residual sugar, but are not often thought of as a dessert wine.

So to define a dessert wine as a sweet wine, is really too simple a definition. It would be best to define a dessert wine as any wine which is served after the meal either with dessert, or as dessert. But for the purpose of this article, we will define dessert wines as wines commonly drank after the meal either with dessert or as dessert; and leave the legal definitions up to the lawyers.

If we are going to assume MOST dessert wines contain residual sugar, we need to look at the production techniques that produce wines with residual sugar. The first way to produce a wine with residual sugar is to have a high concentration of sugar dissolved in the grape before it is harvested and then allow fermentation to only convert part of the sugars to alcohol, leaving residual sugar. This technique is seen in wines such as Muscato, and pre-fortified ports. However, in most cases, these low-alcohol wines are then fortified (such as port) leaving a wine with high residual sugar, and high alcohol. You can make wines with high alcohol and high residual sugar by adding sugar to the “must” after you have crushed the grapes (chaptalization). This gives the wine enough sugar to ferment to alcohol, and still have residual sugar to give the dessert wine its sweetness.

Besides limiting the fermentation of all the sugar (either natural or added), another way of ending up with a sweet wine is to add sweetener to the wine AFTER it is fermented. This can be as simple as adding sugar to the wine (as is done in some low quality wines), or adding sussreserve (as in champagne dosage), or as is the case with PX sherry’s.

Finally, you can produce sweet wine by adding sweetness before fermentation, during fermentation, and after fermentation; and you can also produce a sweet wine WITHOUT fermentation. In this case (as is done most often in Australia), alcohol (grape spirits) are added to unfermented grape juice. In this case, you are getting fortified grape juice; which makes a very flavorful dessert wine.

Let’s take a closer look at each of these production techniques. The first production technique mentioned above is to start with grapes that have very high sugar content and then stop fermentation before all the sugar is converted to alcohol, resulting in residual sugar. Normally, this would produce a wine that is low on alcohol, yet high on residual sugar. But what if you started with a grape “must” that was so high in sugar that you could produce a wine of normal alcohol level (12% abv +/-) AND still had enough residual sugar to produce a sweet wine. There are several options to do this available to the wine maker.

First, there are some grapes that are simply naturally high in sugar content: such as Muscat. That is why Muscato di Asti is often enjoyed as a dessert wine. The grape grower can leave the grapes on the vine longer, leading to a grape called “late harvest” where the sugar content is above normal (and the acid levels very low). This method of harvesting grapes at different levels of sweetness (sugar content) is the basis for most German Rieslings, where you have Kabinetts, Spatlese, Auslese, etc. based on the level of sugar at the time of harvest.

In extreme cases the grapes can be left on the vine so long, that they are not harvested until they freeze. These “ice wines” have almost no water left in the grape (either through dehydration or freezing) so the “must” is almost all a sugary liquid. Although this leaves very little “must” to make wine, the wine that is made can be both high (or normal) alcohol levels, with high levels of residual sugar. Ice wines may be the epitome of dessert wines. (Caution: some ice wines are made in large refrigerators and taste significantly different than ice wines made in the vineyard).

Another way to start with a “must” with an extraordinary high level of sugar is to dry the grapes after they are harvested (called “passito”). This technique is most common in Italy, where the grapes are laid out to dehydrate AFTER they are picked. Using either natural, or man made, drying facilities, the grape sugars are concentrated by allowing the water in the grapes to evaporate. Once the grapes are turned into raisons, the winemaker can then make the wine, and either produce a high alcohol wine (e.g., Amarone), or a normal-alcohol wine with residual sugar (e.g., vin santo).

Finally, the most famous (in my opinion) way of naturally producing a grape “must” with high concentration of sugar versus water is botrytis, or Noble Rot. Botrytis is a mold which grows on the grape and removes water out of the grape whilst imparting new flavors of honey and apricot to the future wine. The result is low water content in the grape and a very high concentration of sugar. This process takes very exacting weather conditions, and can easily turn the entire crop to rotten grapes unfit for making wine. But in the locations of the world with the right weather conditions, this process can produce exquisite dessert wines.

The second way of producing a sweet wine was to ‘adjust” the “must” after the grapes are crushed, and during fermentation. This technique is called “chaptalization” and is used to both produce wines of normal alcohol and no residual sugar (when harvest conditions produce “must” of low sugar levels), and also wine with normal alcohol AND residual sugars. Low end dessert wines often use the chaptalization method, or adding sugar/sweetener during fermentation to produce sweet wines at the lowest cost. However, it is important to know that chapitalization is illegal in many countries, and if done, is not permitted by that regions wine laws. However, in the US, many of the sweeter wines (e.g., white zinfandel) use this technique to produce consistently sweet wine, at the lowest cost.

The third way of making sweet (dessert) wines is to add sweeteners AFTER the fermentation. In this process the wine maker produces the wine, and then adds a sweetener to the finished wine. There are several ways of doing this, and several sweetening agents which can be added. The most famous process of making sweet wine by adding sweetener AFTER fermentation is Champagne, where a small amount of wine with varying amount of residual sugar are added during the “dosage.” This small amount of added residual sugar makes the difference between a Brut, a Dry (extra Dry), or Semi-dry. And although Champagne is not thought of (normally) as a dessert wine; it is often served with wedding cake at dessert time.

The addition of sweetener after fermentation is often called Süssreserve, where some of the “sweet” grape juice is held in “reserve” to be added back to the finished wine to produce wine of normal alcohol level, but added sweetness. However, adding the sweet reserve back to the fermented wine does have a dilution effect, and will lower the overall alcohol by volume. So the result is a lower alcohol, sweeter, wine. Many German wines are made in this technique. There are some good reasons for using sweet reserve instead of simply stopping the fermentation while there is still residual sugar. Mainly stopping fermentation is a difficult thing to do (in winemaking), especially stopping it at an exact level of sweetness and alcohol; and stopping fermentation requires some intervention, whether the use of additional sulfur compounds (sulfites), or heat, or some other technique which could affect the finished wine.

Finally, a sweetener can be added to the wine which is not sweet reserve, or held-back wine; the winemaker can add honey, or other non-grape sweetener to the fermented wine to give it a sweetness after the fermentation has finished.

The final way of producing a sweet wine is to produce the “wine” without fermentation. In this technique, alcohol (normally grape spirits) is added to unfermented grape juice. So the resulting “wine” is normal alcohol level, but retains all the sugar that was available in the grape juice. This technique eliminates all the pitfalls associated with the fermentation process, and allows the wine to be produced very quickly and with a very high level of consistency.

There are at least four winemaking techniques to making wine with residual sugar; or dessert wines. Each technique has its own pros and cons, and good and bad advantages. Based on the above basic understanding of dessert wines, we will have four follow-on articles talking about wines made in each of these four methods, and hopefully give you a greater appreciation for dessert wines.

So until next time, drink good wine.