The Science of Winemaking: Understanding the Process and Ingredients

There are few things in life as comforting as snuggling up on the couch with your favourite glass of wine in hand. Aside from being the beverage of choice for many around the world, wine also has a rich and fascinating history that spans thousands of years. This unique drink can be traced back to ancient civilizations such as Egypt, Greece, and Rome, where wine was used for both religious and secular purposes. In fact, archaeologists have traced the world's first known wine creation back to the people of the South Caucasus in 6,000BC.

If you’ve ever wondered what goes on behind the scenes for months (if not years) before you ever head to the supermarket or bottle shop to buy wine , then you’ve come to the perfect place. The winemaking process can be broken down into several stages, each of which is essential to creating a quality wine. Today, we’ll be exploring the science behind winemaking, across both the fermentation process and in selecting the ingredients used for each bottle.

Wine 101

Although it probably needs no introductions, wine is an alcoholic beverage made from fermented grapes or other fruits. It is typically produced by crushing and fermenting grapes, which convert the sugars in the fruit into alcohol and carbon dioxide. The resulting liquid is then aged in barrels or tanks, where it can develop its flavour and aroma before being bottled and consumed (by you).

Wine can be produced in a variety of styles, ranging from dry and light-bodied to sweet and full-bodied. The flavour and aroma of wine can vary greatly depending on the type of grape or fruit used, as well as the fermentation and ageing process. Some common types of wine include red wine, white wine, rosé, sparkling wine, and fortified wine.

Winemaking Ingredients

Before we dive into the process of winemaking, it is important to first understand the main ingredients that contribute to the perfect glass. There are several key ingredients involved in winemaking, each of which plays a crucial role in the final product.

Let’s explore some of these ingredients below:

Grapes: Of course, there is no wine without grapes. Grapes are the primary ingredient in winemaking and they contain natural sugars that are converted into alcohol during fermentation. The type of grape used will affect the flavour, aroma, and colour of the finished product. Generally, there are two main types of grapes used in winemaking. Vitis vinifera, also known as common grapes, are used to produce most of the world's wine, while Vitis labrusca is used to produce wines such as Concord grape juice.

Yeast: Yeast is a critical ingredient in the winemaking process, as it converts the sugars in the grape juice into alcohol and carbon dioxide through the process of fermentation. The most common yeast generally associated with winemaking is Saccharomyces cerevisiae, which also happens to be the same yeast used in brewing and bread making. This is why many breweries can often smell like bakeries!

Sulphur Dioxide: Sulphur dioxide (SO2) is a preservative that is commonly used in winemaking to prevent oxidation and microbial spoilage. It also helps to prevent oxidation, which can cause the wine to turn brown and lose its fresh flavours and aromas. Sulphur dioxide is added to the ‘must’ (another name for ‘young wine’) in small quantities, typically around 50-100 parts per million (ppm). It is important to note that In some countries such as the US, wine labelled as organic cannot contain added sulphur dioxide.

The Winemaking Process

Now, let’s get into the meat and potatoes of winemaking. As a general rule, there are five basic stages or steps to making wine. Each stage is critical to the quality of the final product, and winemakers must carefully monitor and adjust each step to ensure the best possible outcome.

Let’s explore these crucial stages below:

• Harvesting

When it comes to how wine is made, it all starts with plucking grapes off a vine, also known as harvesting. Harvesting usually occurs in Autumn (Feb - April in the Southern Hemisphere), when the grapes are fully ripe and ready for picking. The timing of harvest is critical, as grapes harvested too early may not have sufficient sugar content, while grapes harvested too late may overripe and produce wine with far too much alcohol. Overall, the method for picking grapes doesn’t have much impact on the wine itself, and can either be carried out manually or with the help of a picking machine.

• Crushing

Once grapes have been harvested, it’s time to crush them. Back in the day, ancient winemakers used to crush grapes in large barrels, with workers stomping on them with their bare feet. If the thought of that makes you feel a little queasy, there is no need to worry. Thankfully, modern winemaking often uses mechanical presses to crush the grapes more efficiently and hygienically. The grapes are crushed to release their juice, or again ‘must’. The must is then filtered using a process called racking, which ensures that all the sediments are gone.

• Fermentation

Now, it’s time to let science do its magic. After the grapes have been crushed, the must is transferred to fermentation vessels, where yeast is added to begin the fermentation process. As we mentioned earlier, the yeast consumes the sugars in the must during fermentation, in order to convert them into alcohol and carbon dioxide.

The temperature and duration of fermentation are critical to the final flavour and aroma of the wine, as different strains of yeast produce different flavours and aromas under different conditions. At this point, wine producers may mix in other additives, such as artificial colours, sweeteners, and preservatives like sulphur dioxide, which we touched on earlier in the article.

• Ageing

After fermentation is complete, the wine is aged to develop its character and complexity. The ageing process can add a host of complex flavours and textures to wine. Ageing can occur in a variety of different vessels, such as oak barrels, stainless steel tanks, or even in bottles. The type of vessel used for ageing will have a significant impact on the final flavour and aroma of the wine, as oak barrels can impart flavours such as vanilla and spice, while stainless steel tanks preserve the fruit flavours and aromas.

This phase of the winemaking process normally takes between 6 to 30 months, with shorter ageing times for white wine and longer ageing times for red wine.

• Fining, Bottling & Corking

Last but not least, once the wine has been aged to the winemaker's satisfaction, it is finally bottled and corked. However, before this can be done, the wine needs to go through a filtration process known as ‘fining’. This process involves removing unwanted particles from the wine, which could make it look cloudy or off-colour. To achieve this, fining agents such as bentonite, egg whites, gelatin, isinglass, activated carbon or Polyvinylpolypyrrolidone (PVPP) may be used.

After the fining process, the wine is ready to be bottled into sterile glass wine bottles that are filled from the bottom via a tube. The final step in the winemaking process is to label and package the wine for distribution and sale, ready to end up in your shopping cart.

Appreciating The Winemaking Process

As you can see, going from grape to glass is certainly no easy feat. Wine production is a delicate scientific, chemical process. By understanding the various factors that go into producing wine and how they contribute to the final product, we can gain a deeper appreciation of the craftsmanship and skill required to produce high-quality wine. Whether we are sipping a glass of wine with friends or visiting a local vineyard, taking the time to appreciate the artistry and tradition of winemaking can enrich our experiences and help us to develop a deeper connection to this beloved beverage.

And there you have it — everything you need to know about the art that is winemaking. We hope that this article has given you some valuable insight into the ins and outs of your favourite bottle of vino. The next time you enjoy a glass, take a moment to savour the complex flavours, aromas, textures and rich history that is associated with life’s sweetest nectar.