Benefits & challenges of producing drinking alcohol in modern distilleries

To truly master the art of crafting spirits like brandy, gin, rum, mezcal, tequila, vodka or whisky, distilleries need sustainable and efficient solutions that can adapt to the challenges of modern production. Each of these spirits, with its unique flavor profile and quality standard, requires precise, reliable processes that ensure both purity and consistency. But beyond the nuances of crafting a perfect spirit, distilleries face common challenges, such as maximizing ethanol yield, managing waste by-products sustainably and keeping up with rigorous environmental regulations.

Types of stillage in alcohol production

The type of stillage produced varies significantly based on the raw materials used in the distillation process. Each type has unique characteristics and requires specific processing methods to optimize recovery and waste management.

Fruit Stillage

• Source: Produced during the distillation of fruit-based spirits such as brandy, which uses a variety of fruits (e.g., berries, apples, pears).

• Characteristics: Contains 40-80% suspended solids, often resembling fruit puree or pomace. The texture depends on the fruit processing method, with some resulting in a fine, mash-like consistency.

• Separation Solution: Due to the high solids content, a Flat Cone Decanter –401 type is recommended based on Flottweg trials, effectively handling the thick, puree-like texture of fruit stillage.

• Challenges: The high solids content and potential variations in particle size require a decanter that can handle heavy loads without compromising separation efficiency.

• Special Cases: Consistency may vary based on fruit type and milling methods.

Vinasse

• Source: Derived from spirits distilled from sweeteners such as molasses, syrups, and thick, sweet juices; commonly found in rum, mezcal and tequila production.

• Characteristics: Contains 1-15% suspended solids, consisting of fine, smooth solids with a pasty consistency.

• Separation Solution: For vinasse, Sedicanters® and separators deliver high-performance separation due to the low solids volume. For smaller operations or higher solids content, the Flat Cone Decanter – 401 offers a cost-effective alternative.

• Challenges: The fine particle size and pasty texture require precise separation to avoid product loss and optimize yield.

• Special Cases: Variations in sugar content and viscosity may require equipment adjustments. High temperatures often used in processing can influence equipment material choices due to thermal stress.

Grain Stillage

• Source: Produced from distilling spirits like whisky and vodka, which use grains such as corn, barley, rye, and wheat.

• Characteristics: Grain stillage contains 40-50% suspended solids with visible sediment that separates into coarse and fine fractions. Depending on the grain type, coarse particles (larger than 20μm) can be easily separated by a decanter, while fine residues often require additional separation.

• Challenges: Cereals with high gluten content tend to produce a higher fine solids content, which can reduce separation efficiency and affect the centrate quality.

• Special Cases: For malt whisky, initial wash separation often reduces suspended solids before distillation, leaving fine materials such as yeasts, proteins, and grain particles in the distillation residue.

• Separation Solution: For high coarse content, a Steep Cone Decanter – 454 type is effective, while a larger decanter or a Sedicanter® is recommended for fine-particle-dense stillage.

Each type of stillage demands specialized equipment and techniques to maximize by-product recovery, manage waste and maintain efficiency in the distillery. By adjusting the process to the specific characteristics of each stillage type, distilleries can enhance yield, meet environmental standards and optimize operational costs.

The art of distillation & why each spirit requires an unique production process

1. Mash preparation: Mash preparation is the foundational step in the production of distilled spirits, setting the stage for all subsequent processes. The raw materials used for making spirits can be broadly categorized based on their composition: those high in natural sugars and those rich in carbohydrates that can be converted into sugars.

• Sugary raw materials: These include fruits (such as grapes and berries) and sugary vegetables (like sugarcane and sugar beets). Due to their high natural sugar content, these materials can proceed directly to fermentation once they are properly prepared.

• Starchy raw materials: Starchy sources, such as cereals (corn, wheat, rye) and starchy vegetables (like potatoes), contain carbohydrates that need to be broken down into fermentable sugars through enzyme action. This initial breakdown is crucial for starchy materials to undergo fermentation successfully.

2. Milling and pressing: To make starch or sugar accessible for enzymatic action, raw materials are processed to release fermentable sugars. Crushing and pressing are used for fruits, while milling is essential for cereal grains to break down their tough outer layers. In some cases, such as sugarcane, a combination of milling and pressing is necessary to extract maximum sugar.

3. Mashing: This step involves mixing the ground or pressed raw material with water in specific ratios, allowing enzymes to convert the available starches into fermentable sugars. This enzymatic breakdown is critical in transforming starchy materials into a sugar-rich mixture suitable for fermentation.

4. Filtration / Lautering: After mashing, the liquid phase, also called wort, is filtered to separate any solid residues. This step is particularly common in malt whisky production, where the sugar-rich wort is clarified before moving on to fermentation.

5. Fermentation: In this stage, the cooled mash, typically around 20-30°C, is transferred to a fermenter or “washback” where yeast is added to convert sugars into alcohol and carbon dioxide. As the yeast ferments the mash, it produces a liquid called “beer” or “wash,” which contains a moderate alcohol level. This liquid will later be distilled to reach the desired purity and strength. Some yeast can be “re-pitched” for future batches, though most of it is discarded to maintain the quality and consistency of the final spirit.

6. Distillation: Distillation is essential for concentrating and purifying alcohol, achieved by separating alcohol from water through evaporation and condensation. As alcohol evaporates at a lower temperature than water, it can be collected and condensed into a liquid with a significantly higher alcohol content. Depending on the spirit’s desired quality and alcohol level, this process may involve multiple distillations. A common approach is a two-step distillation: the first produces “low wines,” and the second refines it further into “high wines.” Distilleries use two main types of stills for this process:

• Pot Still: Ideal for batch processing, pot stills are associated with more aromatic spirits like brandy, cognac, and malt whisky. They require pre-filtering of the mash to avoid fouling and allow for smooth distillation.

• Column Still: Designed for continuous distillation, column stills handle mashes with solids directly and are used to efficiently strip wash into distillate. For a highly purified product, multicolumn systems are employed, enabling spirits like vodka to reach up to 95% ABV.

7. Filtration: Filtration is an essential step in refining certain spirits, used to remove impurities and enhance smoothness. For example, charcoal filtration is common in vodka production, where it helps eliminate unwanted compounds, resulting in a cleaner taste. Some vodka producers use milk as a natural clarifier, with milk proteins binding to impurities that are then filtered out. Tennessee whiskey undergoes a unique filtration known as “sugar maple charcoal mellowing,” in which the spirit is slowly filtered through sugar maple charcoal to impart a distinctive mellow character and subtle smokiness. These techniques contribute to the unique profiles and high quality of each spirit.

8. Coloring: Coloring is a key post-production step, especially for spirits like brandy or cognac, where a sugar liqueur is added to achieve a rich, appealing hue. This step enhances visual appeal and also subtly rounds out the flavor, contributing to the smoothness and richness that consumers expect from premium spirits. Precision in the coloring process ensures consistency across batches, maintaining the brand’s quality and aesthetic appeal while meeting consumer expectations.

9. Aging and Flavoring (if applicable): Certain spirits, such as whiskey or rum, may undergo an aging process in wooden barrels or be infused with botanicals or other ingredients. This step adds unique flavor profiles, depth, and character to the final product.

10. Proofing: Spirits are often at a higher alcohol concentration than intended for the final product. By adding water, distillers reduce the strength to a consistent, market-ready level. This process not only standardizes the alcohol content but can also influence the flavor profile, as dilution allows certain aromas and subtleties to emerge. Proofing requires careful measurement and gradual adjustments, as even slight variations in water addition can alter the spirit’s taste and texture.

11. Blending and bottling: Blending is an essential final step in spirit production, particularly for spirits like whisky, where it’s used to balance and harmonize flavors across different batches. By combining spirits from various casks or batches, distillers can achieve a desired profile in terms of taste, aroma, and texture. Even minor adjustments in the blend can significantly impact the overall character of the final spirit. Bottling is done under hygienic conditions to maintain the high quality of the finished spirit.

Addressing industry challenges in alcohol production with modern solutions

Producing pure alcohol for high-quality spirits involves a series of carefully controlled steps to transform raw biomass into refined alcohol. Each stage, from fermentation to purification, is essential to ensure the final product meets the strict standards required for spirits.

Maximizing yield and purity in fermentation

Achieving a high yield of pure alcohol from feedstock requires precise control over fermentation conditions, such as temperature, pH, and nutrient availability. Inefficient fermentation can lead to lower ethanol content and quality, impacting the overall production process.

• Solution: Flottweg centrifuges optimize the removal of yeast cells and other fermentation by-products, allowing for cleaner separation of the ethanol and enhanced nutrient recovery. This process prevents impurities from building up, ensuring that only the highest purity alcohol moves forward in production. They also provide real-time data on separation efficiency, feed consistency, and solid-liquid ratios. This data can be used to fine-tune fermentation parameters on the go, maintaining a high yield and steady ethanol purity.

Efficient stillage processing post-distillation

Stillage, the by-product of distillation, contains valuable nutrients and can be challenging to handle due to its high-water content. Traditional drying methods for stillage are energy-intensive and costly, so distilleries require efficient ways to process this material.

• Solution: Flottweg Decanters allow mechanical dewatering, reducing the water content in stillage to cut down drying costs and energy use. The Decanters use SIMP DRIVE® and RECUVANE® technology to achieve precise control over energy use. SIMP DRIVE® allows for variable speed adjustments based on feed conditions, optimizing power use, while RECUVANE® recycles rotational energy, supporting the main drive and reducing total energy consumption by up to 30%.

Meeting environmental standards for waste management

Waste and by-product disposal from alcohol production must meet strict environmental standards to avoid penalties. For example, thin stillage cannot simply be disposed of in fields.

• Solution: Distilleries can implement sustainable practices, such as converting thin stillage into biogas or animal feed, which not only helps manage waste but also provides an additional revenue stream. Our partners offer separation equipment and integrated systems that convert waste into valuable by-products.

Wear protection and maintenance for long-term efficiency

Alcohol production involves abrasive substances that can wear down equipment over time, increasing maintenance costs and downtime.

• Solution: Flottweg’s wear-resistant Decanter Centrifuges are designed with reinforced components and easy maintenance features, ensuring long-lasting, reliable performance and minimal downtime.

With the right equipment and approaches, distilleries can elevate both their product quality and sustainability practices. If you’re looking to optimize your day-to-day distillery operations, contact us for a full audit.