How fermentation works in Winemaking? (feat. Oray Wine) || Fermentation 101 || Wine Making

Fermentation is at the core of winemaking, changing grape juice into the wines we enjoy—whether it's a crisp white wine, the greatest red wine, or a bottle of joyous champagne. This natural process is powered by yeast, namely Saccharomyces cerevisiae, which transforms carbohydrates to alcohol and flavours. Winemakers frequently fine-tune the process by inoculating yeast and adding nutrients like di ammonium phosphate to guarantee a smooth and thorough fermentation. The aeration method can also help maintain the yeast healthy and prevent typical problems like slow fermentation and yeast infections. Whether you're interested in the science of fermentation or want to improve your craft, understanding these phases is critical to producing wines that truly shine.

Content:

1.       Activation of dry yeast (Rehydration Procedure)

2.       Yeast starter culture

3.       What is yeast assimilable nitrogen (YAN)

4.       Role of Diammonium phosphate (DAP)

5.       Aeration process

Activation of dry yeast (Rehydration procedure)

Yeast hydration recommendations might differ across vendors. In the first case, carefully follow the manufacturer's instructions as outlined on each yeast sachets. The suggestions provided here constitute a simplified generic yeast hydration approach that will improve the hydration and fermentation capacity of most Saccharomyces cerevisiae cultures. This general approach may not produce excellent results with non-Saccharomyces cerevisiae or other non-Saccharomyces cultures. Furthermore, specialised yeast reactivation preparations can increase yeast function when inoculating poor (very clarified/high °Brix/°Baume) juices or musts. For more precise information, contact your yeast supply or manufacturer.

Equipment and materials required

·         Water (Clean water/ RO water)

·         Yeast

·         Grape juice (No Preservatives)

·         Thermometer

·         Vessel with large surface for hydration 

Inoculation

Following the manufacturer's suggestions. The yeast producer has discovered the best method for rehydrating and activating a certain variety of dried yeast.

An inoculum of 0.25 g yeast/L (25 g/HL) juice is recommended to reach a minimum of 5×106 viable cells/ml. This is based on the ADWY which has 2×1010 cells/g. Because of their reduced liquid capacity, high solids musts are often infected with 0.20 g yeast/kg (approx. 20 g/HL).

For highly clarified juices, high °Brix/°Baume juices/musts, or musts with inhibitory residual SO2 (>10-15 mg/L free SO2 / >30-50 total SO2), a higher inoculum rate of up to double the standard rate is permitted. Oxidative procedures, including the use of hydrogen peroxide, can be employed to reduce excessive residual SO2.

Rehydration of Yeast

·         Pre-heat water at 35-40^oC; check the temperature properly by thermometer.

·         Add that water to the vessel.

·         Rehydrate ADWY by sprinkling it slowly and evenly over the surface of 5-10 times its weight in water (e.g. for 500 g sachet of yeast by suspending in 2.5 to 5 L).

·         Avoid forming yeast clumps. Clumping results in yeast that is neither wetted or rehydrated, and so inactive. Gentle stirring (do not use a powerful mechanical instrument, since this might harm the cells) can assist disseminate certain strains with hydrophobic qualities.

·         Allow to stand for 10-15 minutes.

Amelioration step

·         Stir the slightly settled, rehydrated yeast.

·         The yeast culture should be gradually chilled to within 5-10°C of the juice/must to be inoculated; this improvement procedure appears to be especially significant for difficult-to-ferment juices/musts.

·         Cooling can be accomplished by gradually adding adequate amounts of clean water or juice (with low residual SO2) from the tank to be infected over the course of 10-20 minutes. Steps of 5-10°C are common.

·         When using just water, the yeast should be injected promptly after the chilling processes are finished to minimise cell inactivation. If this is not feasible, add an equivalent amount of juice to the yeast culture and inoculate within a few hours, before the sugars diminish.

Inoculation

·         To give the yeast culture an edge over indigenous strains, the juice/must must be equal to or greater than 15°C when injected.

·         Active fermentation normally starts within 24 hours. If not, examine a juice/must sample under a microscope to determine the proportion of budding and live yeast cells. If these indices are low, a fresh yeast culture may need to be reinoculated.

·         Once active fermentation begins, the fermentation temperature can be adjusted within a narrow range. Temperature variations greater than 3-5°C per day have been shown to partly inactivate budding yeast.

Yeast should be stored precisely according to the manufacturer's guidelines, typically refrigerated; non-optimal storage conditions can result in activity loss, which might lead to unforeseen fermentation difficulties. Do not open yeast sachets between vintages. For difficult to ferment juices/musts, it is recommended to utilise fresh batches of yeast made using unique reactivation (inactivated yeast) preparations.

Yeast Starter Culture

To prepare your starter culture, make diluted juice:

·         Mix 1 litre of juice with 1 litre of chlorine-free water to make 2 litres of juice at about 15 degrees Brix. Use clean water. If there is any chlorine, remove it by boiling or sparging.

·         Maintain low SO₂ levels (≤ 5 mg/L free, ≤ 50 mg/L total). If it is too high, you can reduce it with hydrogen peroxide.

Sterilise everything.

·         Transfer the juice to a sterile 2 L container (such as a conical flask or bottle). Sterilise using heat, 70% alcohol, or 2% SO₂ solution.

Add Nutrients:

·         to keep the yeast happy, add 2 grammes per litre of diammonium phosphate (DAP) to the juice.

Inoculate with yeast:

·         Transfer yeast from the agar slope to the juice. Rinse the slope with about 5 mL of sterilised juice before adding it to the juice mixture.

·         Aerate with filtered air (50-100 mL/min) and keep the temperature between 20-25°C. Warmer temperatures equal quicker growth!

·         Check the yeast every 8 hours. Once it reaches ~2 × 10⁸ cells/mL, it is suitable for usage.

Barrel Inoculation

·         Gradually increase the temperature of the beginning culture to match the juice (no more than a 2°C variation per hour and a maximum 5°C difference at inoculation).

·         Use 2 L of starting culture per 200 L of juice for a solid inoculation rate of ~2 × 10⁶ cells/ml.

Scaling for large quantity

For ≤1,000 L of Juice:

·         Make more diluted juice at 15°Brix and modify the pH (3.1-3.4) and YAN (>180 mg/L) to maintain the yeast thriving.

·         Add the starting culture to larger volumes:
2 L culture plus 2 L juice equals 400 L batch.
2 L culture + 8 L juice equals 1,000 L batch.

·         Continue to aerate (250-500 mL air per minute) and keep an eye on the yeast. Inoculate when the concentration reaches around 2 × 10⁸ cells/ml.

For >1000L of juice:

·         Use a yeast propagator to expand in 10x increments (e.g., 2 L → 20 L → 200 L → 2,000 L). Each step takes 1-2 days, so plan ahead.

·         If necessary, cool the culture to ~5°C and continuously aerating to prevent yeast from settling.

Yeast Assimilable Nitrogen (YAN)

Nitrogen is essential for yeast development and good fermentation. It has an impact on fermentation pace, completeness, and the sensory profile of the wine, such as the development of fruity or reductive qualities. Yeast Assimilable Nitrogen (YAN) analysis allows winemakers to check nitrogen levels in grapes, musts, or juices and treat shortfalls with inorganic solutions such as di-ammonium phosphate (DAP) or organic yeast nutrients. Winemakers may improve the flavour character of their wines by efficiently regulating nitrogen levels. However, adding too much nitrogen, particularly from inorganic sources, raises the chance of ester taint development.

YAN is estimated by combining measurements of ammonia (NH₃) and alpha-amino nitrogen (αAN) utilising enzymatic tests, spectroscopy, or chromatography. YAN levels in Australia typically vary from 50 to 450 mg/L, with 100-200 mg/L being the most frequent. White wines normally require at least 150 mg/L of YAN, while red wines require at least 100 mg/L. Higher YAN levels (250-350 mg/L) are good for clean and fruity flavours, particularly in Chardonnay, but too much nitrogen might harm the wine's fragrance and leave residual nitrogen in the final product.

Sampling for YAN analysis is most successful when conducted close to harvest. Juice samples are recommended; however, pulp and skin samples may be more suitable for skin-contact cultivars. Samples should be obtained in cool to mild temperatures 1-2 weeks before harvest, excluding seeds. To guarantee reliable findings, samples sent for examination should be cleared and treated with sulphur dioxide. Nitrogen levels are carefully managed throughout the process to maintain optimal yeast vitality, consistent fermentation, and high-quality wine production.

Role of Di-ammonium Phosphate (DAP)

Di-ammonium phosphate (DAP) is essential for providing yeast with the nutrients it requires to flourish, particularly during the rehydration phase. Consider rehydration to be the yeast's "wake-up call" following dormancy—it's a critical period in which they prepare for the hard job of fermentation. Adding DAP during this stage provides yeast with a readily available source of nitrogen, which is required for the production of proteins, enzymes, and other cellular components necessary for growth and activity. Without sufficient nitrogen, yeast may struggle to operate, resulting in slow or even blocked fermentations.

Using DAP during rehydration also prepares yeast for a smoother start when it enters the must or juice. It reduces stress on the yeast, allowing them to remain robust and resilient in the face of demanding fermentation circumstances like as high sugar levels or cold temperatures. By ensuring that the yeast is well-nourished from the start, you not only improve fermentation efficiency but also assist to avoid the creation of off-flavors caused by stressed or underperforming yeast.

However, it's important to note that DAP should be taken with caution. Too much nitrogen might result in undesirable scents such as ester taints in the finished wine. So, it's important about striking the right balance—enough to nurture the yeast but not so much that the wine loses its flavour.

Aeration Process

Aeration is an important stage in winemaking that can improve the fermentation process and the overall quality of the wine. Winemakers may increase fermentation efficiency, minimise unwanted traits, and bring forth more brilliant flavours by gradually adding oxygen at important stages. Aeration in red wines helps create "red fruit" flavours, smoothes the taste by lowering astringency, and reduces off-putting reductive smells. It is essential for accelerating fermentation in white wines, especially in difficult batches.

Understanding the correct equipment and processes is essential for any winemaker wishing to experiment with aeration techniques. There are several ways to improve your winemaking process, from selecting the right equipment to knowing when and how to inject oxygen. Many wineries, regardless of size, have found success in using these principles, honing their craft, and producing greater outcomes in flavour and style.

To understand more about aeration and how to use it in winemaking, check read my blog post, Introducing Oxygen to Your Wine Fermentation. It includes everything from basic advice to sophisticated insights that will help you master this critical practice.

To summarise, fermentation is the core of winemaking, converting grape juice into the wines we know and love. Understanding the role of yeast—specifically Saccharomyces cerevisiae—is critical for making the greatest red wine, crisp white wine, or even champagne. Yeast inoculation, adequate nutrient utilisation (such as di ammonium phosphate), and the aeration process all contribute to a smooth fermentation trip. Paying attention to these factors not only avoids yeast infections, but also improves the taste and quality of your wine. By mastering these components, you may improve your winemaking talents and produce wines that are genuinely unique. Cheers to discovering the fascinating realm of fermentation—your path to creating excellent wines!

 Featured Article from Oray Wine:

What is Cock & Féret?

Cock et Féret was an important directory of Bordeaux chateaux (wine estates) which initially published in 1845 as Bordeaux, its Wines, and the Claret Country by Charles Cocks, an Englishman who died in 1854.

Féret translated this directory into Bordeaux et ses vins in 1850. He attached particular care to the categorization of wines from the Bordeaux region according to their qualities and value. Read more...

 

 

Why Do We Age Our Wines? || Aging and Maturation || Wine Making

Wine aging is an ancient practice that continues to captivate the curiosity of wine enthusiasts and professionals alike. From historical traditions to modern cellar techniques, aging wine serves a variety of purposes, encompassing chemical evolution, enhanced sensory experiences, and even investment opportunities. This article delves into the rationale behind aging wine, explores its processes, and addresses its implications for both students and professionals in the field.

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Myths About Aging Wine

One prevalent myth is that all wines improve with age. In reality, most wines are crafted for immediate consumption and do not possess the characteristics necessary for prolonged aging. These characteristics typically include intense flavor profiles and natural preservative qualities, such as high acidity or tannins. Only a small fraction of wines are considered "ageworthy," and even these follow a bell curve of optimal aging: too young, just right, and too old.

For aspiring sommeliers and winemakers, developing the ability to evaluate a wine’s aging potential is an invaluable skill. Academic programs, such as the WSET Level 3 Award in Wines, focus on teaching this through structured tastings and theory-based learning.

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What Happens During Wine Aging?

Aging transforms wine at both the chemical and sensory levels. Initially, young wines are dominated by primary aromas—fresh fruits, flowers, and herbs. Over time, these aromas diminish due to the breakdown of compounds such as geraniol (responsible for rose aromas) and isoamyl acetate (banana aromas). In their place, tertiary aromas emerge, shaped by subtle oxidation and complex chemical reactions.

Examples of tertiary aromas include:

• Walnut and caramel: Resulting from oxidation.
• Almond and honey: Developed through reactions with oxygen-exposed compounds.

Simultaneously, the wine’s structure evolves. In red wines, tannins—known for their mouth-drying quality—undergo polymerization, creating a smoother texture. Whites, on the other hand, may develop a waxy or oily mouthfeel, adding layers to their complexity. For wine students and professionals, understanding these transitions helps craft wines that reach their peak expression.

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The Art and Philosophy of Aging Wine

Aging wine is more than a chemical transformation; it’s an art that embodies patience, curiosity, and reverence for time. Renowned wine collector Queena Wong likens the process to human growth: "A baby is different from an adolescent and a mature adult. The DNA is the same, but maturity brings out its pure essence." This poetic analogy highlights why aging wine resonates deeply with connoisseurs and collectors.

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Which Wines Benefit from Aging?

Not all wines are suitable for aging, and for some, aging is intrinsic to their identity. Certain styles, such as Vintage Champagne, Madeira, or Barolo, are aged extensively before release, enhancing their complexity. Others, like red Rioja Gran Reserva or Vin Jaune, must meet legal aging requirements before entering the market. These extended aging processes often influence their premium price points.

Examples of wines suited for aging:

• Vintage Champagne
• Grand Cru Classé Bordeaux
• Tokaji Aszú

Conversely, light, aromatic wines like Moscato d’Asti or Provence Rosé are designed for immediate enjoyment and are not meant for long-term storage.

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Practicalities of Aging Wine

Proper storage is crucial for aging wine. Key conditions include:

1. Temperature: Cool and constant, ideally between 10°C and 15°C (50°F to 59°F).
2. Light and Vibrations: Avoid direct light and movement to maintain wine stability.

Urban dwellers may face challenges in creating optimal conditions at home. In such cases, temperature-controlled storage facilities or professional wine brokers can provide a solution.

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Aging Wine as an Investment

For some, aging wine transcends personal enjoyment and becomes a financial endeavor. High-demand wines with iconic status, such as super-premium Bordeaux or Burgundy, are often sought as investment pieces. The principle is simple: as these wines age and become rarer, their value increases. However, investing in wine requires meticulous research, as market trends and consumer preferences can shift over time.

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Aging for Memories

Beyond taste and profit, aging wine can serve a sentimental purpose. Bottles from milestone years—birthdays, anniversaries, or significant events—carry memories that surpass their chemical composition. These wines symbolize cherished moments, creating an emotional connection that no price tag can define.

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Conclusion

Aging wine is a nuanced practice that blends science, art, and personal choice. For wine professionals and enthusiasts, understanding why and how wines are aged provides insight into their evolution and opens the door to enriching sensory and emotional experiences. Whether for taste, tradition, or investment, aging wine continues to reflect the timeless allure of this ancient beverage.

How to Find Vegan Wine and What It Is? || Vegan Lifestyle || Viticulture and Enology

Given that grapes are used to make wine, many wine enthusiasts might believe that all wines are suitable for vegans. However, non-vegan ingredients are frequently added throughout the winemaking process. The subtleties of vegan wine, the reasons why some wines aren't vegan, the changing methods in vegan winemaking, and helpful advice on identifying vegan-friendly bottles are all covered here.

How Come All Wine Isn't Vegan?
Although wine seems to be made from plants, the manufacturing method reveals otherwise. The majority of wines go through a process called fining, which eliminates undesirable tannins, harsh flavours, and haziness. By adding a binding agent to the wine, fining makes it easier to filter out these particles since it sticks to them.

The conventional fining chemicals that are employed present a hurdle.

1. Red wines frequently use egg whites (Albumin) to lessen harsh tannins and astringency.
2. White wines are stabilised and clarified by the use of casein, a milk protein.
3. Isinglass: Often found in beer and some wines, isinglass is extracted from fish bladders.
4. Animal bones and skins are the source of gelatin, which is used to clarify wines.

Although these compounds are eliminated prior to bottling, their presence during the process renders the wine ineligible for vegan certification. For vegans, this distinction is significant because their worldview encompasses manufacturing techniques in addition to ingredients.

The Transition to Vegan-Friendly Methods:
Winemakers are investigating synthetic or plant-based fining substitutes in response to the increasing demand for vegan goods. These choices are more in line with moral and ecological principles and are just as successful:

1. Bentonite clay is a popular natural fining agent that draws impurities without lowering the quality of the wine.
2. Activated charcoal is a versatile and vegan-friendly solution that is well-known for its filtration properties.
3. Unfined and Unfiltered Wines: Some winemakers choose not to fin their wines at all, letting them stabilise and clarify on their own over time. Vegan customers can easily identify these wines because they are frequently labelled as such.

Although there are synthetic alternatives like PVPP, many environmentally conscious companies prefer natural agents like bentonite. These changes show how the industry is becoming more in line with vegan principles.

Does Wine Taste Different for Vegans?
You may be confident that vegan wine does not sacrifice flavour. Wine's flavour is influenced by:

• Grape Variety: The most important factor influencing flavour is the variety of grape utilised.
• Terroir: The wine's profile is shaped by the soil, climate, and vineyard circumstances.
• Winemaking Techniques: Additional factors that affect flavour include fermentation and oak ageing.

Because natural stabilisation techniques or vegan fining chemicals don't affect flavour, winemakers can preserve consistency and quality.

How to Spot Vegetarian Wines?

Since wine labels are exempt from disclosing production techniques, it might be difficult to identify vegan wines. To be sure your decision is in line with vegan principles, use these helpful steps:

• Check for Certification: Some wines have certificates that indicate they are vegan, like the BeVeg mark or other insignia. These certifications ensure that no items produced from animals were utilised in the manufacturing process.
• Examine online directories: A comprehensive database of vegan wines, beers, and spirits can be found on websites such as Barnivore. Customers can check the vegan status of their favourite beverages by searching by producer or brand.
• Request Transparency from Producers: On their labels or websites, several wineries provide details about their production processes. If you require clarification, don't be afraid to get in touch with them personally.

Are Sustainable and Organic Wines Vegan?
There is a widespread misperception that sustainable or organic wines are inherently vegan. The use of animal-based fining agents is not regulated by these certifications, despite their emphasis on chemical-free and ecologically friendly agricultural methods. A wine must specifically specify that it is organic or employ alternate fining techniques in order to be considered both vegan and organic.

Comprehending Wine Descriptions.
Vegan customers may become confused by terms like "leather," "honey," or "meat" in tasting remarks. These adjectives refer to complex flavour profiles created by fermentation, ageing, or particular grape properties rather than the usage of animal ingredients.

The Significance of Vegan Wine.
The increasing popularity of vegan wine is a reflection of larger trends towards sustainable and ethical consumption. By selecting vegan wines, customers help:

• Animal welfare is the process of removing products made from animals from production.
• Sustainability: Promoting actions that have the least negative effects on the environment.
• Transparency: Encouraging winemakers to communicate and label their products more clearly.

The wine industry's shift to vegan-friendly products as plant-based diets become more popular shows its dedication to satisfying consumer demands without sacrificing quality.

Where to Buy Vegan Wines?
Finding vegan-friendly wines has never been simpler because to the growing popularity of veganism. This is where to begin:

• Specialised Stores: There are now a lot of wineries and internet merchants with vegan-only sections.
• Supermarkets: Vegan-friendly options are frequently marked on shelf labels.
• Online directories: Websites such as Barnivore provide easy-to-use resources for finding vegan producers and brands.
• Wine apps: Vivino and other similar tools let users look for wines based on customer feedback or vegan certifications.

You can choose vegan wines that are consistent with your ideals with confidence if you use these tactics.

Vegan wine is more than just a fad; it's a necessary component of sustainable and moral wine consumption. Wine enthusiasts may now make well-informed decisions that align with their beliefs without compromising on quality or flavour because to increased awareness and resource availability. Thus, there are many tasty and varied possibilities for vegan wines, whether you're looking for them for moral reasons or just out of curiosity. Let's hope that every glass can be filled with grapes and guilt-free in the future!

Feet First: The Art of Grape Crushing on Foot || Traditional Method || Wine Making

In a world dominated by new winemaking machinery, the old technique of crushing grapes with bare feet persists. Many artisanal winemakers support this custom, which is generally viewed as a lovely vestige of the past. They enjoy its physical advantages and cultural significance.

Crushing grapes is an important step in winemaking since the objective is to extract juice without destroying the seeds, which might release unpleasant chemicals. The delicate, steady pressure of human feet makes them excellent for this activity, resulting in refined flavours and controlled tannins.

The Douro Valley in Portugal is a prime example of this method's legacy. For generations, foot treading in shallow granite troughs known as lagares has been synonymous with quality Port wine production. While modern machinery has superseded traditional procedures in most situations, several high-end producers continue to use foot treading for their best batches.

Boutique vineyards across the world embrace the process, especially for small-batch production. These winemakers believe that foot treading gives them more control over fermentation, which improves the wine's texture and flavour. Furthermore, the practice strengthens their bond with their craft, making each batch a labour of love.

The romantic charm of foot treading is more than simply utilitarian; it also tells a captivating tale that appeals to current wine connoisseurs. Wines manufactured using this traditional process entice consumers looking for authenticity and legacy. Some wineries use this narrative as a marketing tool, distinguishing their bottles in an increasingly automated business.

Those concerned about cleanliness should rest easy: winemaking techniques assure safety. Wine's alcohol concentration naturally neutralises most viruses, making foot-treaded wine just as safe as machine-produced wine. Some wineries maintain hygiene by wearing sterilised boots, but bare feet remain iconic.

Foot treading, while not popular, represents the balance of tradition and skill. The next time you drink a glass of wine, consider the centuries-old process that may have contributed to its creation—a reminder of the artistry behind each bottle.

Kegging Wine - When to add Nitrogen? || Kegging of wine || Wine making

Hello, wine lovers! Today, we go on an exciting adventure into the world of wine kegging, a method that is revolutionizing how we preserve and serve our favorite vintages. Whether you're a seasoned expert or just starting out in the wine business, understanding the complexities of kegging, particularly with nitrogen, may take your wine experience to new heights. Join me as we explore the art and science of kegging wine and learn how to maintain your wines with nitrogen.

Why Keg Wine?

Before we get into the technicalities of nitrogen and kegging, let's first understand why kegging wine has grown in popularity among both amateur enthusiasts and professional winemakers. Traditional bottling processes, while ageless, can provide difficulties in terms of storage, preservation, and serving. Kegging addresses these issues by giving unprecedented ease while assuring consistent quality with each pour.

Furthermore, kegs minimize the possibility of cork taint and oxidation, two major enemies that can undermine the quality of bottled wine over time. Kegs maintain the freshness, taste, and fragrance of wine by keeping it under pressure in a sealed atmosphere, ensuring that each sip is as enjoyable as the first.

Introducing Nitrogen, The Guardian of Wine Quality.

Let's now focus on the star of the show: nitrogen. Nitrogen, an inert gas, is essential for wine preservation because it forms a protective barrier that keeps oxygen out of the wine. As any seasoned wine specialist will tell you, oxygen is wine's deadliest enemy, capable of irreversibly damaging its delicate tastes and aromas. By adding nitrogen to the keg, we can successfully reduce the danger of oxidation and increase the shelf life of our wines.

But how can we identify the best time to add nitrogen to our kegs?

This is when experience and knowledge come into play. As someone who professionally kegs a lot of wine, I've found that once it's in a stainless-steel keg, wine doesn't mature or change very much. As a result, kegging should be considered the final stage in the winemaking process.

Age the wines as you usually would, enabling them to acquire the ideal flavor profiles and complexity. Once you're pleased with the maturing process, think of kegging as the equivalent of bottling your wines. Ideally, the keg should be filled to the capacity to reduce headroom. If there is unavoidable headspace, it is critical to purge it with nitrogen or another inert gas, such as Argon/CO2, to prevent oxidation and extend the wine's life.

Best Practices for Kegging Wine With Nitrogen

Now, let's look at some recommended practices for kegging wine using nitrogen to ensure maximum preservation and quality:

Before closing the keg, purge the headspace with nitrogen to remove any remaining oxygen. This process is critical for establishing a protective atmosphere that keeps the wine fresh and flavorful.

Maintain Constant Pressure: Keep your nitrogen tank connected to the keg at all times and use nitrogen to drive the wine from the keg into the glass. To reduce oxygen exposure and protect the wine's integrity, avoid opening the keg too frequently.

Follow Beer Brewing Techniques: Borrowing from the beer brewing playbook, consider filling the keg with nitrogen and bleeding the pressure release valve many times to achieve complete oxygen removal. This process helps to remove any leftover air from the keg, preventing oxidation and deterioration.

 

Here is the table with most commonly used wine keg sizes.

Keg Type	Capacity (gal/oz)	Height (inches)	Weight (lbs)	Width (inches)
Mini Keg	1.32/169	9.875	13	6.75
Sixth Barrel	5.16/661	23.375	58	9.25
Quarter Bareel	7.75/992	13.875	87	16.125
Slim Quarter	7.75/992	23.375	87	11.125
Half Barrel	15.5/1984	23.375	161	16.125
Cornelius Keg	5.0/640	23	49	9

Advances of kegging your wine:

Serving wine from a stainless-steel keg may lack the romance and history of popping corks, but a 5-gallon (19-L) keg can carry 25 standard (750 mL) wine bottles. Stainless steel kegs, like glass bottles, are inert and will not change the flavor of wine, even when stored indefinitely. Because there is no cork, there is no risk of trichloranisole contamination (TCA, cork taint) or cork breaking, leaking, or chipping. You also do not require a corkscrew!

Kegs also minimize oxidation. The quantity of headspace as a percentage of wine in kegs is significantly lower than in bottles – you fill the keg to the very top. Second, the kegs have great seals since they are designed to withstand pressure, and unless damaged, they do not leak. Finally, before filling the kegs with wine, they are purged with bottled gas, which removes oxygen. This guarantees that the wine tastes precisely the same as the day you bottle it.

When you keg your wine, you can consume one glass at a time without having to open the entire bottle. If you do need a bottle (for a dinner party or a picnic), you can easily fill it from the keg and cork it as needed. Is there a party upstairs? Go down to the cellar with a carafe or jug, and you'll be ready to serve in no time. Because the wine discharged is replenished with oxygen-free gas, it remains fresh until the bottom of the keg.

Kegs also have the advantage of being highly environmentally friendly. Commercial kegs have a 30-year lifetime, but they are mistreated, banged around in storage and handling, and damaged by cleaning equipment and during transit. With care and maintenance, most of the kegs repurposed from the soda industry have many decades of use ahead of them, and each year they'll save cork, capsule, and label waste, to say nothing of cardboard boxes and bottles lost to breakage and shrinkage.

In the end, kegging wine with nitrogen provides several benefits to both amateurs and experts. Understanding the critical role of nitrogen in wine preservation, as well as following proper kegging procedures, can guarantee that your valuable vintages mature gently and thrill your taste with each sip.

FAQs about Kegging of Wine

Can wine be kegged?

Stainless steel, like glass, is an inert surface that does not affect the flavor of your wine. Furthermore, because the headspace may be purged with an inert gas, such as nitrogen or carbon dioxide, oxidation is reduced in your kegged wine. With your wine in a keg, you may enjoy a single glass without having to open the entire bottle.

How long does wine last in keg?

Sparkling wines have a two-week shelf life, whereas still wines have four weeks. The better the conditions, the longer the shelf life (assuming kegs remain refrigerated). Kegs that have not been opened and are kept appropriately will last for 12 months.

Why do you keg wine?

To keep wine fresh, it must be properly maintained (similar to a significant other), avoiding over-oxidation and/or overheating. Kegged wine makes this much easier because the wine never comes into contact with air or gas until it is ready to be given to a visitor, and a keg is less prone to temperature changes.

Can you ferment wine in kegs?

I ferment in a bucket since it would block any keg, and then when it's clear and no longer dropping sediment in a secondary carboy, I transfer it to the keg. So, absolutely, serve, bottle, or anything from the keg.

How do you keg red wine?

So, if you're kegging some red wine, you'd siphon it from your fermenter into the keg and then set your CO2 regulator to a low pressure - maybe 2-3 psi (7 kpa). Seal the lid, apply pressure, and then release the purge valve multiple times to clear any leftover air from the keg.

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Carbonic maceration in wine || What is carbonic maceration, effects of carbonic maceration on wine || Wine making

 

What is Carbonic Maceration?

Carbonic maceration is the process of putting completely intact entire bunches of grapes in a closed fermentation chamber filled with carbon dioxide. A variety of intracellular responses occur within grape berries that have been handled in this way. Enzymes carry out these processes in the absence of oxygen, with no yeast or microbial activity. The enzymatic processes last about a week at temperatures up to 35°C, after which they stop due to the minimal amount of alcohol generated. The fruit is then destemmed, crushed, and fermented with yeast under standard winemaking conditions.

What reaction happens during carbonic maceration and what is the impact of carbonic maceration on the grape berry/ wine?

The grape berries absorb carbon dioxide, filling them up to around 50% of their capacity. Reactions within the berry, which is still alive while whole, transition from respiratory to anaerobic metabolism.

Malic dehydrogenase is an important enzyme in carbonic maceration because it converts malic acid to ethanol, succinic acid, and aminobutyric acid without creating lactic acid. As a result, titratable acidity decreases and pH increases.

Grape alcohol dehydrogenase converts sugar into ethanol and CO2. Only 0.5-2.2% of ethanol is created, which might be because at this concentration, ethanol begins to impair cell membrane integrity. The amount of carbon dioxide created during the first 24 hours is roughly equal to that absorbed.

Glycerol and shikimic acid are produced, with shikimic acid accumulating within the berry and then degrading to cinnamic acids, and then to the three main aroma compounds associated with carbonic maceration: benzaldehyde ('cherry', 'kirsch', 'almond'), vinylbenzene ('styrene', 'plastic'), and ethyl cinnamate ('cinnamon','strawberry', 'honey'). Other enzymes that can create volatile scents that may contribute to carbonic maceration flavor include ethyl and methyl vanillate ('vanilla'), ethyl 9-decenoate ('sweet', 'fruity', 'quince'), and 1-octanol ('almond'/'buttery').

Carbonic maceration wines generally have lesser primary fruit flavors, which might be due to reduced concentrations of some common wine esters. For example, hexyl acetate ('fruity', 'green', 'pear') can only develop in an oxygen-rich environment during crushing, therefore its formation would be reduced in the anaerobic environment of carbonic maceration.

What is the impact of carbonic maceration on the wine?

Carbonic maceration wines have a particular scent that frequently polarizes tasters. The scents can be characterized as 'fruity' or'musk-like', with'strawberry/raspberry' and 'cherry/kirsch' aromas (especially in Beaujolais wines), as well as 'vanilla','spice', 'almond', 'cinnamon','sandalwood', or 'oak-like' qualities. These characteristics frequently overpower any varietal fruit character, although they can also provide scent to wines with little varietal or fruit character.

In general, the wines are softer, less acidic, and have lesser phenolic component extraction. They are said to develop more quickly than normally fermented wines. As a result, the approach has traditionally been suggested for lighter-bodied/fruity wines meant for early consumption. According to sources, Australian winemakers are experimenting with carbonic maceration or partial whole bunch fermentations in Pinot Noir and Shiraz to produce more refined and aromatic wines, as well as to help in blending.

Effects of carbonic maceration on the phenolic compounds in wine/ grape berries.

Carbonic maceration differs from traditional winemaking in terms of phenolic extraction from grape skins, such as anthocyanins and tannins. While ethanol serves as a solvent for phenolic extraction in both procedures, conventional fermentations have a greater proportion of skin and seed contact time at higher alcohol concentrations than carbonic maceration, resulting in more anthocyanins and tannins being extracted. Carbonic maceration causes anthocyanins to spread from the epidermis into the pulp, resulting in a pink flesh. Any tannin extracted into the pulp at low alcohol percentages is more likely to be skin tannin rather than seed tannin, which may give the impression that the wine has softer tannins.

Risks during carbonic maceration.

Carbonic maceration increases the risk of spoiling by acetic acid bacteria and Brettanomyces yeast due to the higher pH, hotter temperatures, and lack of sulfur dioxide. Furthermore, if a carbon dioxide-rich atmosphere is not properly maintained, aerobic microbes can swiftly take control, resulting in wine deterioration.

How do you do it?

Michel Flanzy created the initial method in 1934. A modified version, patented by Stephen Hickinbotham in 1986, features complete grape bunches packed in a plastic bag supported by a pallet box, which already contains a tiny amount of dry ice in an insulated container. The plastic bag is then sealed and occasionally supplied with a one-way valve that allows carbon dioxide to exit while preventing air from entering.

Carbonic maceration flavor and structure are best achieved when grapes are held at temperatures between 30-32°C for 5-8 days. Lower temperatures provide more delicate and short-term scents, although the strength varies depending on the grape variety or wine style. Carbonic maceration occurs more easily in a gaseous atmosphere, hence the amount of juice produced by the berries is frequently inversely proportionate to the degree of carbonic maceration taste. With more juicing and more aerobic conditions, yeast and bacteria fermentation can occur, with the resultant flavors, as well as those from stem touch, limiting or outweighing those from carbonic maceration.

References

Etaio, I. Elortondo, F. J. P. Albisu, M. Gaston, E. Ojeda, M. Schlich, P. 2008. Effect of winemaking process and addition of white grapes on the sensory and physicochemical characteristics of young red wines. Aust. J. Grape Wine Res. 14:211-222.

Cowey, G. 2018. Ask the AWRI: Carbonic maceration Aust. N.Z. Grapegrower Winemaker (651): 70-71.

Ducruet, V. 1984. Comparison of the headspace volatiles of carbonic maceration and traditional wine. Lebensmittel- Wissenschaft & Technologie 17(4): 217-221.

Flanzy, C., Flanzy, M., Benard, P. 1987. La vinification par la maceration carbonique. Paris: INRA.

Sneyd, T. N. 1989. Carbonic maceration: an overview. Aust. N.Z. Wine Ind. J. 4(4): 281-282.

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Malolactic fermentation in red wine.|| MLF/Fermentation || Wine Making

 

Malolactic fermentation (MLF) is a secondary bacterial fermentation that occurs in most red wines. Oenococcus oeni, a member of the lactic acid bacteria (LAB) family, is the primary bacterium responsible for MLF owing to its capacity to withstand the severe circumstances of wine (high alcohol, low pH, and low nutrition) and produce good wine sensory qualities.

One key purpose of MLF is to provide microbiological stability for the subsequent metabolism of L-malic acid. MLF specifically eliminates L-malic acid from wine, which can serve as a carbon source for yeast and bacterial development, potentially resulting in spoilage, spritz, and unpleasant flavours. MLF can also be used in select wines to alter their character.

MLF can be generated by inoculating a specific bacterial strain or happens spontaneously during primary fermentation. Because natural or 'wild' MLF can be unpredictable in terms of onset time and influence on wine quality, malolactic starter cultures are widely employed.

This article provides practical information for induction of MLF in red wine. Achieving effective malolactic fermentation provides further practical instructions for MLF induction, monitoring, and maintenance.

Essential parameters for a successful MLF in red wine.

• Composition of Red Wine or Must.

Alcohol, pH, temperature, and SO2 concentration are key wine compositional parameters influencing MLF performance. Before beginning with MLF inoculation, it is advised to test these parameters and make modifications as needed. Each of these parameters has a range within which MLF is beneficial. As one or more of these criteria grow unfavourable, the MLF will become more challenging (the variables are cumulative). The table below summarises favourable and unfavourable circumstances for MLF in red wine and provides further explanation.

Parameter	Favourable	Unfavourable
Ethanol (%v/v)	<14	>16
Temperature (℃)	18 -22	>16 - <25
pH	3.3-3.5	<3.3
Total SO2(mg/L)	<30	>40

• Alcohol

The possible alcohol concentration of red wine is an important factor to consider while inducing MLF. It is advised that wines with a potential ethanol level more than 15-16% v/v utilize an ethanol-tolerant strain of malolactic starting culture. Furthermore, co-inoculation should be explored since it may help the bacteria culture adapt to increased ethanol concentrations during fermentation. Consider pre-adapting the starting culture to high ethanol conditions.

• Temperature

The optimal growth temperature for LAB in grape juice is approximately 30°C. However, when ethanol content increases, the optimal temperature decreases due to the harmful effects of ethanol on bacteria at higher temperatures. Temperature should be 15-25°C (ideally 18-22°C when other factors are unfavourable and alcohol concentration is about 10% v/v). Inoculation temperature is crucial as it is the development stage that is most vulnerable to suboptimal temperatures. Temperatures over 25°C slow down MLF, increasing the danger of bacterial deterioration and volatile acidity. When using co-inoculation, it's important to prevent high temperatures throughout the alcoholic fermentation process.

• pH

Higher pH levels, especially over 3.5, promote growth of MLF bacteria and other spoilage germs such as Pediococcus and Lactobacillus strains. To prevent the formation of spoilage bacteria in red must and wines with pH levels above 3.5, consider co-inoculation and post-MLF stabilisation.

• SO2 concentration

Lactic acid bacteria, particularly Oenococcus oeni, are extremely sensitive to the molecular form of SO2. To prevent the harmful effects of molecular SO2 on malolactic bacteria, it is recommended that must/wines for MLF induction have no detectable free or molecular SO2. It is worth noting that traditional SO2 measurement methods in red wines, such as aeration-oxidation, can overestimate free and molecular SO2 concentrations. Total SO2 content is a good indicator of a wine's possible influence on malolactic bacteria and MLF, since bound SO2 may hinder them.

Adding a maximum of 50 mg/L total SO2 to grapes before crushing is not expected to negatively impact MLF. However, due to the possibility of SO2 buildup from various extrinsic (e.g., grape harvesting and shipping) and intrinsic (e.g., yeast strains employed in alcoholic fermentation) sources, it is advised that an accurate total SO2 measurement be performed prior to MLF induction.

For ideal MLF conditions, young red wine should have a total SO2 level of less than 30 mg/L. Total SO2 concentrations above 40 mg/L might delay or totally inhibit malolactic fermentation (MLF), depending on the malolactic bacteria strain and wine conditions. Concentrations above 50-60 mg/L may completely inhibit MLF.

• Other inhibitory factors

Pesticide residues, elevated copper levels in the vineyard, and yeast-derived medium-chain fatty acids can all impede MLF.

MLF strain selection criteria for red wine.

• Bacteria strain tolerance

When selecting a malolactic starter culture, it's important to consider the strain's tolerance to the physical and chemical conditions of the wine. This is especially true when selecting a strain for red must/wine, where, for example, in wines with an ethanol level of 15-16% v/v or more, the strains available are limited to those with high alcohol tolerance.

• Malolactic starter cultures for red wine: Oenococcus oeni and Lactobacillus plantarum.

Commercial malolactic starter cultures consist of many Oenococcus oeni strains, each with unique sensitivities to various winemaking conditions and uses. However, starter cultures of Lactobacillus plantarum, another member of the wine lactic acid bacteria family, are becoming accessible for use in red winemaking. Winemakers can use L. plantarum strains' specific physiological features to induce MLF in red wines.

• Yeast-bacteria compatibility

The compatibility of primary fermentation yeast with malolactic bacteria is a significant determinant in the success or failure of MLF. Certain yeast strains may block MLF by producing metabolites such as SO2 and certain fatty acids. Using a yeast strain with high nitrogen demand, especially under low YAN must circumstances, might deplete the nitrogen pool for malolactic bacteria. To lessen yeast inhibitory effects on MLF in red wines, choose an appropriate yeast/bacteria mix (according to supplier/manufacturer recommendations).

• Period of inoculation

Bacteria can be inoculated at various phases of the winemaking process, with sequential and co-inoculation being the most prevalent ways. Timing decisions may be influenced by processing concerns and the type of starting culture employed.

Co-inoculation, which involves inoculating malolactic bacteria at the beginning of alcoholic fermentation (18-24 hours after yeast inoculation), is becoming increasingly popular. Importantly, especially in red winemaking, co-inoculation may potentially facilitate:

• A shorter overall fermentation time, which can lower the risk of spoilage by other microorganisms including Brettanomyces.
• Overcoming MLF problems associated with high ethanol levels and reduced nitrogen content at the end of primary ferment.
• Co-inoculation can improve the usage of particular Lactobacillus plantarum strains for MLF in red winemaking.

Lactic acid bacteria are sensitive to SO2, hence when co-inoculation is performed, bacteria should be added after yeast activity has been detected. After adding SO2, wait at least 18-24 hours after inoculation to allow yeast to bind the free SO2. Co-inoculation requires temperature management, especially in red wines where high fermentation temperatures can harm both bacteria and yeast.

There may be some risks associated with co-inoculation, including:

• Inhibition by high SO2 added during harvest/crushing
• Competition with yeast growth
• Antagonistic yeast/bacteria relationships (MLF strain compatibility is thus important.)
• Stuck primary ferments causing possible production of acetic acid from LAB.

In some red winemaking applications, several timing choices might be employed. Delaying the beginning of MLF, for example, may help to retain colour in lighter-colored red wine varietals from colder winemaking locations. Furthermore, for certain commercial preparations of Lactobacillus plantarum, the producer may prescribe inoculation of a specific starter culture prior to the start of alcoholic fermentation.

Role of Monitoring MLF in quality control parameter in red winemaking.

Monitoring MLF completion is crucial for ensuring quality control in red wine production. Regular assessment of L-malic acid content allows for correct commencement and completion of MLF, as well as efficient post-MLF wine stabilisation (e.g., SO2 addition and pH adjustment).

Controlling MLF with a chosen malolactic strain requires determining its onset. Regular monitoring can easily establish the incidence of delayed or stalled MLF, and if necessary, a rescue starting culture may be immediately deployed. This avoids the dangers associated with uncontrolled proliferation of spoiling bacteria.

To determine MLF completion, strive for a 'not found' malic acid result (<0.05 g/L by enzymatic assay). However, a result of 0.1 g/L or fewer is low enough for the MLF to be regarded nearly complete and to reduce the danger of MLF spoiling after bottling. Precise monitoring of MLF completion reduces the possibility of uncontrolled growth of other wine microorganisms, as well as spoiling. Delays in post-MLF wine stabilisation, in particular, can result in increases in volatile acidity and other spoiling events. Wines are susceptible to oxidation and spoiling from microbes including acetic acid bacteria and Brettanomyces. Accurate identification of MLF completion is therefore critical in preventing such spoilage and quality degradation.

Co-inoculation can lead to MLF completion before alcoholic fermentation. In such instances, it is advised that post-MLF wine stabilisation be carried out once alcoholic fermentation is complete.

References

• Howe, P.A., Worobo, R., Sacks, G.L. 2018. Conventional measurements of sulfur dioxide (SO2) in red wine overestimate SO2 antimicrobial activity. Am. J. Enol. Vitic. 69: 210-220.
• Nordestgaard, S. 2019. AWRI Vineyard & Winery Practices Survey.
• Coelho, JM., Howe, P.A., Sacks, G.L. 2015. A headspace gas detection tube method to measure SO2 in wine without disrupting SO2 equilibria. Am J. Enol. Vitic. 66: 257-265.

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