Clase de VINO 2026

Introduction to Fermented Beverages

Overview of the Class Structure

• This class focuses on fermented beverages, specifically wine and beer. The first part will cover wine, while the second part will address beer.

Key Topics Covered in Wine Production

• The session will include definitions related to wine, grape maturation (vendimia), and the basic process of wine production. It will also discuss stages of production and potential alterations during stabilization and aging.

Understanding Grapes for Wine Production

Definition of Grapes

• Grapes used for winemaking are defined as mature, healthy, clean fruits from the Vitis vinifera species that have not undergone fermentation or dehydration post-harvest. These grapes are essential for producing genuine wines through alcoholic fermentation.

Importance of Timely Processing

• Freshly harvested grapes must be processed quickly to prevent deterioration; otherwise, they lose internal liquid and structural integrity, accelerating the winemaking process. Historically, grapes were transported long distances but this practice has ceased due to quality concerns. All wines must now be produced within their respective growing regions.

Regulations Surrounding Wine Production

Protection of Wine Origin

• There are regulations in place that protect the origin of wines based on soil characteristics and climate conditions specific to each region, which influence how wines are produced. Each wine's unique attributes stem from its geographical location.

The Vendimia Process

Determining Harvest Time

• Vendimia refers to the harvest time when grapes reach optimal maturity for winemaking; this is assessed by enologists through visual inspections and analysis of fruit characteristics such as color and size changes alongside sugar-acid ratios known as maturity index.

Role of Enologists

• Enologists play a crucial role in determining when grapes should be harvested by conducting regular evaluations until they observe signs like wilting peduncles (the stems holding grape clusters). They also analyze laboratory data regarding sugar content before deciding on harvest timing.

Instituto Nacional de Vitivinicultura's Role

Regulatory Oversight

• The Instituto Nacional de Vitivinicultura oversees legislation concerning viticulture in Argentina, ensuring quality standards for safety and compliance with health regulations while analyzing annual harvest data to predict future vintages' characteristics based on initial assessments made at vendimia time.

Maturity Index Standards

• For optimal grape maturity suitable for winemaking, sugar-acid ratios should range between three and five; glucose-fructose levels need to fall between 0.92% - 0.95%. These metrics guide producers in assessing readiness for harvesting grapes effectively throughout different seasons each year.

Understanding Grape Maturation and Wine Production

Grape Maturation Process

• The grape is considered industrially mature when the average weight of the bunches reaches its maximum, with no significant increases in sugar levels. This indicates a stable relationship between glucose and fructose, as well as sugars and acids present in the grapes.

• Various methods exist to measure sugar concentration in grapes, including refractometric, densitometric, and chemical methods. Each method has specific units of measurement that must be adhered to for determining grape maturity.

Fermentation Process

• Once harvested, grapes undergo alcoholic fermentation where sugars (glucose and fructose) are converted into ethyl alcohol and carbon dioxide through a chemical reaction. This process is fundamental to wine production.

• During fermentation, secondary products such as glycerin and volatile acids are also produced alongside alcohol from the initial sugars present in the fruit. Yeasts play a crucial role in this transformation; they can be intrinsic or added externally to enhance fermentation efficiency.

Sugar Content Impact on Alcohol Levels

• The initial sugar content of grapes directly influences the final alcohol content of the wine produced. For instance, if grapes have an 18% sugar concentration (equivalent to 10 gromé), it typically results in a wine with an alcohol level between 10% - 12%. This correlation is essential for predicting wine quality based on initial sugar levels.

• A scale known as "gromé" expresses sugar content; for example, 10 gromé corresponds to an alcohol yield of approximately 10 ml per 100 ml of wine produced. Understanding these measurements helps winemakers predict final product characteristics accurately.

Stages of Wine Production

• The winemaking process consists of three main stages:

• Pre-fermentative Stage: No fermentation occurs.

• Fermentative Stage: Rapid conversion of sugars takes place.

• Post-fermentative Stage: A slower phase where additional transformations occur after primary fermentation has completed. Understanding these stages is vital for producing different types of wines based on grape variety used (e.g., red vs white).

Understanding Wine Production

Types of Wines and Their Origins

• The type of wine produced depends on the grape variety used: red wines come from red grapes (e.g., Cabernet), while white wines can be made from both white grapes (like Chardonnay, Pinot, Muscat) and red grapes.

Grape Processing Techniques

• The initial step in winemaking involves careful crushing of the grapes to release juice without breaking seeds or stems, which could introduce undesirable compounds into the wine.

• This process is more akin to pressing than grinding; the goal is to allow the grape's own weight to break it down naturally, releasing a liquid known as must.

Use of Preservatives

• After crushing, sulfur dioxide is often added as a preservative in smaller amounts due to technological advancements; it must be declared on labels due to potential allergic reactions.

Fermentation Stages

Rapid Fermentation Phase

• The fermentation process consists of two stages: a rapid phase where differences between white and red wines are established by leaving skins (or "ollejo") in contact with the must for reds.

• Red wine fermentation occurs at higher temperatures (25-35°C), compared to white wine fermentation (19-30°C). During this phase, carbon dioxide is produced and forms a film on top that needs regular removal or submersion back into the mixture.

Sediment Removal Process

• Following rapid fermentation lasting 5-7 days, sediment formed during fermentation is removed through decantation or centrifugation—a process called "descube." This sediment includes skins and other solids.

Transitioning Between Fermentation Phases

Slow Fermentation Phase

• After removing sediments, slow fermentation begins, lasting 20 to 30 days; this stage results in a purer wine with fewer undesirable substances. The process may involve multiple transfers ("trasiego") between containers to further clarify the wine.

Final Storage Considerations

• Modern winemaking utilizes stainless steel containers for final storage due to their inert properties compared to older materials that could affect flavor and quality over time. This evolution reflects advancements in winemaking technology aimed at improving product consistency and safety.

Wine Production Process Overview

Key Stages in Wine Production

• The wine production process includes various materials, such as stainless steel and cement, which contribute different aromas and flavors to the wines. This is particularly relevant during the stabilization phase, which also encompasses aging.

• The main stages of wine production are:

• Prefermentative

• Fermentative

• Post-fermentative

Prefermentative Stage

• In the prefermentative stage, grapes are received and assessed for sugar concentration. Care is taken to avoid damaging the grapes during this phase.

• Sulfiting occurs between crushing and fermentation; sulfur dioxide is added in various forms (e.g., tablets or gas), with dosage depending on grape condition, microbial load, temperature of must, sugar content, acidity levels, etc.

Fermentation Methods

Spontaneous Fermentation

• Spontaneous fermentation utilizes indigenous microorganisms from the grapes themselves. This method results in more complex wines influenced by local terroir.

• Wines produced through spontaneous fermentation take longer (20-25 days), leading to a more natural flavor profile but less predictability in outcomes.

Induced Fermentation

• Induced fermentation typically employs Saccharomyces cerevisiae yeast strains that can withstand low pH levels and produce ethanol efficiently.

• This controlled process ensures consistent quality across batches while minimizing risks associated with spontaneous fermentation diseases.

Chemical Changes During Fermentation

• Controlled fermentation leads to more homogeneous wines with predictable characteristics compared to those produced via spontaneous methods.

• Various acids can form during spontaneous fermentation processes (e.g., succinic acid, fumaric acid). These changes are complex but essential for understanding wine chemistry.

Sugar Consumption and Final Product Characteristics

• During fermentation, sugars like glucose and fructose are consumed by yeasts, contributing to the final alcohol content of the wine. Some residual sugars may remain unfermented (e.g., arabinose).

Understanding Wine Composition and Aging Techniques

The Role of Sucrose in Wine

• Discussion on sucrose presence in wine, indicating that if it remains, the grape was not fully ripe. Mature grapes should have no sucrose unless added, which is prohibited.

Sweetening Agents in Wine Production

• Only must (grape juice) can be added to sweeten wines like rosé. This addition is allowed as it naturally contains sugars.

Fermentation and Chemical Changes

• Various acids generated during fermentation can lead to wine diseases; for instance, ascorbic acid acts as a reducing agent to prevent iron-related spoilage.

Effects of Aging on Wine Quality

• Post-fermentation processes involve transferring must into different containers for stabilization and maturation. Young wines are consumed within the year, while aged wines develop better aromas and flavors.

Types of Containers Used for Maturation

• Wooden barrels are commonly used for aging due to their permeability, allowing controlled alcohol exchange and imparting unique flavors. Other materials like cement are also being utilized in modern winemaking.

Innovative Aging Techniques: Underwater Wineries

Unique Submarine Aging Process

• Some wineries age their wines underwater, where they interact with marine flora and fauna. This method reportedly enhances the wine's characteristics through natural processes.

Special Considerations for Underwater Bottling

• Bottles are sealed with special corks to prevent water intrusion while allowing interaction with seawater. The glass used is thicker to withstand underwater pressure.

Chemical Composition of Wines

General Composition Ranges

• Wines typically contain 70%-90% water, 8%-18% alcohol (commonly around 10%), along with various acids such as succinic (0.05%-0.10%) and acetic acid (<0.13%).

Sugar Content Classification

• Final sugar content influences wine classification: dry wines have <0.2% sugar; sweet wines range from 3%-8%.

Regulatory Standards

• Argentine food code sets limits on acetic acid (1g/L for whites/rosés; 1.2g/L for reds), along with regulations on chlorides, calcium, and methanol levels in wine production.

Nacional de Vitivinicultura and Food Code Regulations

Overview of Legislation in Wine Production

• The Nacional de Bitivin y Cultura is the primary legislation governing wine production, mandating compliance with regulations set by the Instituto Nacional de Vitivinicultura.

• The food code complements this legislation; any additional laws must also be adhered to when producing wine, particularly those related to fermented beverages.

Compliance Requirements for Wine Production

• Producers must follow both the food code and specific regulations from the Instituto regarding advertising and promotion of their wines.

• Allowed practices include adding other grape musts, alcohol, tartaric acid, citric acid, malic acid, clarifying agents, and various yeasts during fermentation.

Additives and Composition Standards

• All additives used in wine production must be part of its typical composition; for example, added alcohol is considered a standard component.

• Certain preservatives like sorbic acid are permitted in specified amounts; however, water or unapproved substances cannot be added to wine.

Restrictions on Wine Alteration

• It is prohibited to create wine from non-standard sources such as grape pomace or residues unless specifically allowed (e.g., grappa).

• Wines that exhibit degradation or disease are deemed unsuitable for consumption.

Types of Wine Alterations

• Common alterations include microbial changes (aerobic/anaerobic), which can lead to undesirable flavors and aromas due to oxygen exposure or residual sugars.

• Aerobic alterations may result in "flor" formation or acetic spoilage characterized by vinegar-like odors.

Examples of Microbial Spoilage

• Anaerobic fermentations can produce off-flavors through lactic fermentation leading to unpleasant tastes reminiscent of cheese.

• Both aerobic and anaerobic spoilage can significantly affect the quality of wine, resulting in turbidity and undesirable sensory characteristics.

Microbial Effects on Wine Quality

Lactobacillus and Wine Alteration

• The action of Lactobacillus in wine can lead to undesirable changes, such as the production of various acids that result in pale, turbid wines with unpleasant odors.

• Affected wines may exhibit a foul smell reminiscent of spoiled cabbage or sauerkraut, indicating significant microbial spoilage.

Malolactic Fermentation

• Malolactic fermentation involves the conversion of malic acid into acetic acid, which can lead to a "vinegar-like" taste if the acetic acid levels exceed acceptable limits.

Oxidation and Reduction Mechanisms

• Oxidative processes can cause iron ions to oxidize from ferrous (Fe²⁺) to ferric (Fe³⁺), leading to different types of discoloration in wine classified as white, blue, or black breakage.

• Copper ions can also undergo oxidation and reduction reactions that affect wine quality; these reactions depend on the specific ion state involved.

Precipitation Phenomena

• Potassium bitartrate precipitation occurs due to increased alcohol content and temperature drops during malolactic fermentation, affecting clarity and stability.

• Calcium tartrate precipitation results in color changes ranging from whitish to brownish hues in wine.

Summary of Microbial Impact on Wine

• Understanding these microbial alterations is crucial for winemakers; while knowledge of specific diseases isn't necessary, awareness of potential changes caused by microorganisms is essential.

• Advances in technology have reduced the occurrence of these alterations over time.