What Is Must in Wine?

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What Is Must in Wine? Decoding the Essence of Winemaking

Must is the unfermented juice containing crushed grapes, seeds, skins, and sometimes stems, that forms the raw material for winemaking. Essentially, it’s the promise of wine, holding all the potential flavors, aromas, and characteristics that will eventually define the finished product.

Unveiling the Secrets of Must: A Winemaking Foundation

The story of wine begins not in the cellar, but in the vineyard, with the grape itself. However, it’s the transformation of the freshly harvested fruit into must that marks the crucial first step in the winemaking process. Understanding must is key to understanding wine.

The Journey From Grape to Must: A Winemaking Primer

The creation of must involves a series of steps designed to extract the precious juice from the grapes:

Harvesting: Grapes are carefully picked at optimal ripeness, typically determined by sugar levels, acidity, and flavor profile.
Crushing: The grapes are gently crushed to break their skins and release the juice. This process avoids crushing the seeds, as this can release bitter tannins.
Destemming (Optional): Some winemakers choose to remove the stems before or during crushing. Stems can contribute tannins and green flavors, but some winemakers prefer to include them for added complexity.
Pressing (For White Wines): White wines are typically made by pressing the crushed grapes to separate the juice from the skins and seeds before fermentation. This prevents the extraction of color and tannins. Red wines are typically fermented on their skins to extract color and tannins.
Sulfur Dioxide Addition (Optional): Sulfur dioxide (SO2) may be added to inhibit unwanted microbial activity and protect the must from oxidation. This is a common practice, but the amount added varies depending on the winemaker’s philosophy and the condition of the grapes.

The Composition of Must: A Chemical Symphony

Must is a complex concoction, containing a variety of components that contribute to the final flavor and character of the wine:

Water (70-80%): The primary component of must.
Sugars (15-25%): Primarily glucose and fructose, which are fermented into alcohol.
Acids (0.5-1.0%): Tartaric, malic, and citric acids contribute to the wine’s acidity and balance.
Phenolic Compounds: Tannins, anthocyanins (responsible for color), and other compounds that contribute to flavor, color, and mouthfeel.
Nitrogenous Compounds: Amino acids and proteins that serve as nutrients for yeast during fermentation.
Aromas and Flavor Precursors: Compounds that will develop into the wine’s characteristic aromas and flavors during fermentation and aging.
Minerals: Potassium, calcium, magnesium, and other minerals that contribute to the wine’s overall complexity.

The Importance of Must Analysis: Setting the Stage for Success

Analyzing the must’s composition is crucial for winemakers to make informed decisions throughout the winemaking process. This analysis typically includes:

Sugar Levels (Brix/Baume/Oechsle): Determines the potential alcohol level of the finished wine.
Acidity (pH and TA): Influences the wine’s tartness, balance, and aging potential.
Yeast Assimilable Nitrogen (YAN): Determines the amount of nutrients available for yeast during fermentation. Insufficient YAN can lead to sluggish or stuck fermentations.
Phenolic Compounds: Assessing tannin levels, especially for red wines, to predict color stability and aging potential.

Challenges in Must Production: Navigating Potential Pitfalls

Producing high-quality must isn’t always straightforward. Winemakers face several challenges:

Oxidation: Exposure to oxygen can lead to browning and loss of aroma.
Microbial Contamination: Unwanted bacteria and wild yeasts can spoil the must.
Insufficient or Excessive Tannins: The right balance of tannins is crucial for red wines.
Low or High Acidity: Acidity plays a key role in balance and aging.

Transforming Must into Wine: The Magic of Fermentation

Fermentation is the process by which yeasts convert the sugars in the must into alcohol and carbon dioxide. This is arguably the most transformative stage in winemaking.

Yeast Inoculation: Winemakers may use commercially available yeasts or rely on indigenous yeasts present on the grapes.
Temperature Control: Maintaining the correct fermentation temperature is crucial for flavor development and preventing stuck fermentations.
Cap Management (Red Wines): The “cap” of grape skins and seeds that forms during fermentation needs to be managed through techniques like punch-downs or pump-overs to ensure proper extraction of color and tannins.

FAQ: Deepening Your Understanding of Must

What is the difference between “must” and “juice”?

While the terms are sometimes used interchangeably, must typically refers to the entire mass of crushed grapes including the juice, skins, seeds, and potentially stems, while juice usually refers to the liquid portion that has been separated from the solids (particularly relevant for white winemaking).

Does the quality of the must affect the quality of the wine?

Absolutely. The quality of the must is paramount. Factors like grape ripeness, acidity, and absence of defects directly impact the final wine’s flavor, aroma, and overall quality. “Garbage in, garbage out” applies perfectly to winemaking.

Can must be consumed directly?

Yes, must is technically edible and drinkable, but it is extremely sweet and acidic and contains pulp. It’s not usually consumed in large quantities.

What are the key differences between red must and white must?

The primary difference lies in whether the skins are included during fermentation. Red must ferments with the skins, extracting color and tannins, while white must typically has the skins removed before fermentation.

How does “chaptalization” relate to must?

Chaptalization is the process of adding sugar to must to increase the final alcohol content of the wine, typically in regions where grapes struggle to ripen fully. It’s a controversial practice, restricted in many areas.

What role do enzymes play in must preparation?

Enzymes can be added to must to improve juice extraction, clarification, and aroma development. They help break down cell walls, releasing valuable compounds.

How does maceration time affect the must?

Maceration time (the period when juice stays in contact with skins) significantly impacts color, tannin, and flavor extraction, especially in red winemaking. Longer maceration generally leads to richer, more complex wines.

What is “lees contact” and how does it relate to must?

Lees contact refers to aging the wine on its lees (spent yeast cells) after fermentation. This can add texture, complexity, and aroma to the finished wine, and can occur directly within the must after fermentation.

How is the must analyzed for potential defects?

Winemakers visually inspect the must for mold, rot, and other signs of spoilage. They also analyze it chemically for pH, TA, YAN, and volatile acidity, which can indicate potential problems.

Can winemakers correct imbalances in the must?

Yes. Winemakers can adjust acidity by adding tartaric acid or calcium carbonate. They can also add nutrients to correct YAN deficiencies and use enzymes to improve clarification.

What is “saignée” and how does it relate to must?

Saignée (French for “bleeding”) is a winemaking technique where a portion of the red must is removed early in fermentation to concentrate the remaining juice, resulting in a richer, more intense red wine and a rosé wine from the “bled” juice.

What is the ideal temperature for must fermentation?

The ideal temperature varies depending on the style of wine. White wines are typically fermented at cooler temperatures (12-18°C) to preserve delicate aromas, while red wines are fermented at warmer temperatures (20-32°C) to extract color and tannins.