Must

What is Must

Creating must is the first step in the winemaking process.

Must is the freshly crushed grape juice that eventually becomes wine. The term comes from the Latin word “vinum mustum,” meaning “young wine.”

Must consists of:

• Grape juice (the liquid component)
• Grape skins (which provide colour, tannins, and flavor compounds)
• Seeds (contributing additional tannins)
• Sometimes stems (depending on winemaking style)
• Pulp and other solid matter

The solid portion of must is called pomace.

The composition of must varies significantly depending on the grape variety, growing conditions, and the date of harvest. Must is thick due to the presence of skins, seeds, and stems. For red wines, the must typically remains in contact with the skins during fermentation to extract colour and tannins. For white wines, the must is usually pressed and separated from the solids before fermentation begins.

Due to its high sugar content, must is sometimes used as a natural sweetener in various cuisines.

How is Must Weight Measured

Must weight refers to the density of the grape juice, which is primarily determined by its sugar content. Winemakers use several different scales and instruments to measure must weight. Generally, must weight measurement is a standard practice to assess grape ripeness and predict potential alcohol content.

Measurement Tools:

The most common instruments used are a hydrometer or a refractometer. A hydrometer floats in the juice, with the depth it sinks indicating the density. A refractometer uses light refraction and requires only a few drops of juice, making it popular for vineyard testing. The method of measurement can vary between regions or producers, with some preferring traditional hydrometers and others opting for digital refractometers.

Measurement Scales:

Different wine regions use different scales to express must weight. The three primary systems are Brix (used in the Americas and Australia), Oechsle (used in Germany and Switzerland), and Baumé (used in France and some other European countries). Brix directly measures the percentage of sugar by weight, so 24° Brix means approximately 24% sugar content. As an example, a Riesling Kabinett from Germany might have a must weight of around 70–85° Oechsle. Oechsle measures the density difference from water multiplied by 1000, while Baumé uses a different density scale.

Measurements are typically taken in the vineyard before grapes are harvested to determine optimal picking time, and again after crushing to guide fermentation decisions. It is important to note that the must weight readings for each vintage, as must weight can vary significantly depending on the vintage due to climate and growing conditions. Keeping detailed notes helps track vintage differences and fermentation outcomes.

Grape Variety

German wines are amazing for their incredible variety of grape types, with Riesling standing out as the most famous and widely grown grape in the country! The choice of grape variety is important in winemaking; it shapes the wine’s taste, smell, and feel. While some winemakers mix different grapes to create complex and layered wines, single-variety bottles (especially those made from Riesling) are what German wine tradition is all about!

The sugar content of grape juice is carefully monitored through must weight measurements, like degrees Oechsle or Brix, to measure sugar content. This sugar content is mostly determined by the grape variety and the ripeness of the grapes when they are picked. This sugar doesn’t just set how much alcohol the wine will have – it also decides how sweet the wine will be, from bone-dry Kabinett and Spätlese Trocken to sweet Auslese and Beerenauslese. Noble rot (Botrytis cinerea) can affect the grapes, the sugars and flavors are concentrated and produce rare, sweet wines with extraordinary complexity and a hint of honeyed richness!

The grape must (a mixture of juice, skins, seeds, and sometimes stems) plays a really important part in winemaking! The solid portion, or pomace, can make up 7 to 23% of the total weight and has a huge impact on the wine’s color, tannin structure, and how it feels in your mouth. The specific gravity of the must (which shows its sugar content) is a key measurement for winemakers – it tells them both the quality and the potential style of the wine they’re about to make!

Fermentation is the critical step where the sugars in the grape juice get converted into alcohol, and having skins and stems around can influence how much color and tannins get extracted (especially in red wines). Winemakers carefully control fermentation temperature, yeast selection, and how long the skins stay in contact to achieve the right balance and complexity they’re looking for. After fermentation, the wine might be aged in oak barrels or stainless steel tanks, which develops its flavor and character even more!

Vineyard conditions (like soil type, climate, and how much sunlight the grapes get) also play a huge role in determining grape quality! Regions like the Mosel and Rheingau are famous for producing wines with high acidity and exceptional aging potential – characteristics that wine lovers absolutely prize. The timing of harvest is planned very carefully, with winemakers regularly measuring must weight and acidity to make sure grapes are picked at exactly the right moment of ripeness!

German wine production follows strict rules that dictate which grape varieties can be used, how much wine can be produced, and what winemaking practices are allowed – this ensures consistently high standards! The country’s wine regions are divided into different areas, each offering unique styles and flavors, from the crisp, dry notes of Spätlese Trocken to the sweet, golden hues of Auslese. The color of German wines can range from pale yellow to deep brown, depending on the grape variety and winemaking methods used!

The expertise and knowledge of German winemakers, combined with the country’s strict wine laws, have earned German wines a reputation for quality and precision that’s hard to beat! As the market for German wines continues to grow, people are discovering an amazing array of styles, from refreshing, high-acidity whites to rare, sweet dessert wines. German wines aren’t just enjoyed on their own but also play an important role in cooking around the world – they’re regularly featured in food pairings and recipes!

At the end of the day, converting grape juice into wine is a complex journey that’s shaped by grape variety, vineyard conditions, and the skill of the winemaker! Each bottle of German wine tells a story of careful measurement, careful craftsmanship, and a deep respect for tradition – qualities that continue to captivate wine lovers around the world!

Why is It Important

Must weight is one of the most critical measurements in winemaking for several interconnected reasons.

Predicting Alcohol Content:

Since yeast converts sugar into alcohol during fermentation, the sugar content in must directly determines the potential alcohol level in the finished wine. The must is fermented to convert sugar into alcohol, and the degree to which it is fermented affects the wine’s dryness. As a general rule, each degree Brix produces approximately 0.55-0.6% alcohol by volume. This allows winemakers to predict whether their wine will have the desired alcohol level and ensure it meets legal requirements for their region or wine category. The amount of residual sugar left after fermentation determines the sweetness of the finished wine.

Harvest Timing:

Must weight is the primary indicator winemakers use to determine when grapes have reached optimal ripeness for harvesting. Grapes must be ripe at harvest to achieve the desired must weight. Grapes picked too early will have insufficient sugar, resulting in thin, tart wines with low alcohol. Grapes picked too late may produce overly alcoholic, unbalanced wines. Harvest often occurs in the fall, which influences grape ripeness and must weight. By monitoring must weight throughout the ripening season, winemakers can schedule harvest at the precise moment when sugar levels align with their stylistic goals. The development of grapes on the vine directly impacts must weight and ultimately the style of wine produced.

Wine Style and Quality:

Different wine styles require different must weights. Light, crisp wines may target lower must weights around 19-21° Brix, while full-bodied reds or dessert wines may aim for 24-28° Brix or higher. The must weight also provides insight into overall grape ripeness and quality, as properly ripened grapes develop sugars alongside other important compounds like phenolics and flavor precursors. Producers use must weight to classify and label their wines according to legal standards. Some wines, such as Kabinett, are valued for their fresh and vibrant character.

Fermentation Management:

Knowing the must weight helps winemakers plan fermentation strategies, including yeast selection, nutrient additions, and temperature control. Very high must weights may require special yeast strains or dilution, while low must weights might need chaptalization (adding sugar) in regions where this is permitted. After fermentation, the juice is drained from the solids to separate the wine from the pomace. The length of time the pomace stays in contact with the must affects the wine’s color, tannin, and flavor profile.

Conclusion

Must weight serves as a fundamental bridge between viticulture and winemaking, translating the work done in the vineyard into actionable information in the cellar. By measuring the sugar concentration in freshly crushed grapes, winemakers gain crucial insight into potential alcohol levels, harvest readiness, and the likely style and quality of the finished wine. Must weight is one of many factors that determine wine quality alongside acidity, pH, phenolic ripeness, and flavor development. It remains an indispensable tool that has guided winemaking decisions for centuries. Understanding must and must weight is essential for anyone seeking to comprehend how grapes transform into the diverse world of wines we enjoy today.