Technology used in red wine production

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In red wine production, a number of factors go into shaping each wine’s individual character. Key parameters include the location and climate of the vineyard, grape variety and methods of cultivation, ripeness of the grapes, timing of the harvest, approach to pressing the grapes, and, lastly, aging of the wine.

The red wine production can yield vastly different results depending on geographic factors and conditions. Generally speaking, red wine production involves a lot of high-tech these days — from managing processes to recording fermentation parameters and using sensors to monitor the alcohol and sugar content, temperature and coloring. The various types of red-wine and must fermentation tanks further illustrate the level of technical specialization the industry has reached.

Red wine at the top

No matter where you are in the world, wine, for most people, means red wine. This is true of large consumer and producer nations like the US, Canada, Argentina, Chile and Australia as well as the developing markets in Asia and Africa. Reds are also the most popular type of wine in the big wine-producing romance-language countries of France, Italy and Spain.

White wines, on the other hand, have largely been blend wines or wines using such high-yield grape varieties as Ugni blanc, Airén, Trebbiano or Catarratto to provide large quantities of alcohol in the production of spirits.

In contrast, Germany and its neighboring wine-producing countries have been considered white wine countries in terms of cultivation and consumption for a long time now. But this trend has changed: In Germany, Austria and Switzerland, the portion of red grape varieties cultivated for making red wines is now significantly greater than it was in previous decades. Today, reds constitute around 35 percent to 40 percent of the wines produced and around half of the wines consumed, which is why these countries import large quantities of red wine.

© Hermann Pilz

Color composition in red wine production

A 5 percent to 10 percent blend of the dark-red Italian Ancellotta variety is enough to turn the light-colored Lambrusco a dark red. Other varieties of grapes also contain lots of red colorant, and new, specially bred varieties such as the Dornfelder, Acolon and Regent produce a deeply dark red juice.

Whether a wine ends up light red, dark red or a full-bodied burgundy depends on the variety and the anthocyanin content of the grapes. Anthocyanins are a class of compounds in the phenol family that form the building blocks of nearly all plants. They’re water-soluble and can be found not only in sap, but also in skins, flowers and fruits, where they play a role in the wide variety of different colors.

Varieties of grape with a high anthocyanin content in their flesh tend to yield dark-red, sometimes almost black, wines. The Italian Ancelotta variety from Emilia-Romagna is one such grape whose wines appear in a deep, dark red. Up to now, it has been used to color light-red wines.

It’s all in the method

In most varieties of red grape, the color is stored in the skin of the grapes. This colorant is sometimes harder to extract, so red grapes have to be pressed differently than white grapes. Today, you can generally distinguish between three basic types of red wine production.

1. High-temperature short-time method: In this approach, the destemmed grapes (the stalks are known as Rappen, or black horses, in Germany) are crushed in a type of mill, then heated for a short time in a heat exchanger. Immediately after this, the mass is cooled down to avoid any “cooking” flavors or other unwanted changes in the must before fermentation.

2. Must fermentation: This method of fermentation involves using either destemmed, crushed grapes or grapes with their stalks still attached. Depending on the method used, the red colorant is passed into the resulting must in the course of a water extraction or through CO2 or alcohol extraction. This process doesn’t just involve fermentation — that is, the transformation of sugar into alcohol, but also the extraction of color and tannins.

3. Carbonic maceration: Carefully picked whole grapes are subjected to an atmosphere of CO2 in special tanks for several days. The increased carbon dioxide concentration causes the colorants and acids to be released and pass into the resulting must or young wine, leaving the grapes looking bleached.

While the high-temperature short-time method is mostly used for less complex drinking wines from light-colored varieties of grape, must fermentation is the most common method for the production of high-quality red wines. In recent years, many new process techniques and technical devices have been developed in this area, particularly special must fermentation tanks.

Innovation in must fermentation

Original methods of must fermentation can still be found in many southern wine-producing countries. They involve thoroughly crushing the grapes in a grape mill and pumping or pouring them into open fermentation tanks with must pumps. As fermentation begins, a cap is formed from pomace rising to the surface during fermentation as a result of CO2 formation. From time to time, this cap is manually or mechanically punched down using a staff made of wood or stainless steel to intensify the extraction of the grape skins. This approach to gently mixing grapes can vary, which has led to the development of a number of must fermentation tanks such as rotating tanks and must recirculation.

Open must fermentation, a common practice in Mediterranean countries for centuries, is labor intensive and requires a lot of space for open vats. The advantage of producing wine this way is the gentle handling of the grapes and their skins. Punching them down manually means they are exposed to hardly any mechanical stress that can lead to unwanted bitter and astringent compounds. Today, such new technologies as horizontal must tanks with slow-moving agitators that have large paddles or blades are being used to control the extraction as precisely as possible. The tanks are often double-walled and allow the must to be warmed or cooled.

© Speidel Tank- und Behälterbau GmbH

A wide variety of lifting elements allow the must cake to be submerged. Flushing and flooding procedures are also used to enable the entry of more oxygen, which is desirable in most cases as it leads to increased yeast propagation. For top-quality wines, the punchdown process is the best approach. Technological advancements are constantly bringing new and improved techniques, tanks and devices to the market, which work gently, reduce workloads and enable brightly colored, high-quality red wines to be created.

Those wanting to learn more about the technical requirements of red wine production will find everything they need at drinktec from October 4 through 8, 2021, at the Munich exhibition center. Are you still looking for a platform to showcase your innovative products and services in this segment? Then join us at the next drinktec.

Dr. Hermann Pilz

Dr. Hermann Pilz

Dr. Hermann Pilz has been in charge of the trade magazine WEINWIRTSCHAFT as chief editor for over 20 years. He loves writing about many different topics of the wine and spirits industry.