Hopewell Valley Student Podcasting NetworkChemistry ConnectionsThe Chemistry of WineEpisode #9  

Welcome to Chemistry Connections, our names are Erin Goldsmith and Gianluca Procaccini, and we are your hosts for episode 9 of Chemistry Connections. Today we will be discussing the chemistry of red wine.

Segment 1: Introduction to Red Wine Production

In this episode, we will be covering the chemistry of red wine production. We will mainly be discussing the fermentation process that turns the grapes into wine, after the harvesting process, prior to bottling the wine.

To start, we’ll define some key terms:

Ethanol is the form of alcohol that is in wine. Typically in a range anywhere between 7-15 percent.

Tannic acid aka tannins are a naturally occurring molecule which cause a dry feeling in your mouth and are bitter when ingested. Tannins can be extracted from skins, seeds, bark, and plant stems.

Tartaric acid is the one of the components in wine that controls the overall acidity. Too much can cause an overly tart, sharp wine; while too little can cause a wine that is flat and bland.

Sulfites are the component of wine that act as a preservative and an agent that halts the fermentation process which can help protect the wine against potential oxidation or bacterial exposure which could occur at various stages of the winemaking process.

Malic acid is another acid found in grapes that is primarily responsible for sour flavors, its concentration decreases as a grape ripens.

Also, we’ll discuss the origins of wine. Wine was first created in Georgia in 6000 BCE by accident. When stored grapes ended up getting fermented by naturally occuring yeast. After this, yeast became domesticated and spread throughout the Caucuses and then moved into Europe. 

Segment 2: Personal Connections

Erin was interested in researching the chemistry of wine after watching Star Trek Picard. In the first season, Captain Jean-Luc Picard has retired to the French countryside, and now makes wine. The quality of Picard’s wine becomes a running joke in later seasons. 

Gianluca is interested in researching winemaking because of the 100 Days winemaking simulator video game. 

Wine production is an important part of many lives. The wine industry spans multiple countries, continents, and cultures. It is a beverage that has historically brought people together, and has played a vital role in community building across many centuries and places. Wine, along with other forms of alcohol, was used as a main source of water before water purification methods were perfected. It has historical significance that can not be defined but has provided the lifeblood for many businesses, religious ceremonies, and social gatherings.

Segment 3: The Chemistry Behind Red Wine Production

We will be discussing the process behind wine production which include the following steps. 

• Crushing
• Primary Fermentation 
• Cold Stabilization 
• Secondary/Malolactic Fermentation 

The purpose of this process is to release the juice from the grapes, and use the sugar in the fruit to produce the alcohol found in wine. The fermentation process is initiated by certain types of yeast, which is controlled in steps like primary fermentation, secondary/malolactic fermentation. The levels of fermentation can affect the taste and alcohol level of the final product. 

2 AP Chemistry topics discussed in this episode:

• When grapes begin the fermentation process, many acids are released in the form of tannic, malic, and tartaric acids. These acids help contribute to the different aspects of red wine such as bitterness, sourness and acidity respectively.
• Fermentation is a metabolic process that produces chemical changes in organic substances through the action of enzymes. Yeast helps convert the sugar in grapes into alcohol and carbon dioxide during the fermentation process of winemaking

Thank you for listening to this episode of Chemistry Connections. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. 

Sources:

• https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/wine-chemistry
• https://www.science.org.au/curious/earth-environment/chemistry-wine-part-1#:~:text=The%20answer%20is%20simple%E2%80%94chemistry,compounds%2C%20pigment%20compounds%20and%20tannins
• https://www.terravenos.com/trellis/acid-wine 
• https://www.science.org.au/curious/earth-environment/chemistry-wine-part-2-fermentation 
• https://en.wikipedia.org/wiki/Winemaking
• https://www.masterclass.com/articles/learn-about-wine-what-are-tannins
• https://www.extension.iastate.edu/wine/wp-content/uploads/2021/09/compositionofgrapes.pdf 

Music Credits

Warm Nights by @LakeyInspired 

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