How to Detect a Stuck Fermentation

How to Detect a Stuck Fermentation

Recently Barbara wrote in with this question on a possible stuck fermentation: How can I tell if my wine is stuck and not fermenting in the secondary fermenter? Should the airlock be bubbling? -Barbara Matt’s Answer: Hi Barbara, Thank you for reaching out with your question! Being able to identify a stuck fermentation is an important skill to have and can keep you from taking drastic measures when you might not need to. The latter days of a fermentation are going to be much slow.er than primary fermentation. It is certainly possible to get a stuck fermentation at this late stage of the process given that sugar supplies are running out and alcohol levels are getting higher. This makes life hard for the yeast. As such you may only see a bubbles in your airlock every few minutes as things wind down. Using your airlock to gauge fermentation activity is a good idea but you need to check on it periodically to make sure it is still seated properly and that the water levels are correct. If either of these is off the carbon dioxide being produced may be essentially going around the airlock. This brings us to determining whether or not you have a stuck fermentation on your hands or not.   How to Tell if You Have a Stuck Fermentation The easiest way to tell if a wine is stuck is to first taste the wine. If the wine tastes even a little bit sweet you know that there’s sugar left in your wine. As this is what the yeast convert into alcohol, fermentation should not end until all the sugar is gone. If your wine is not sweet then fermentation is likely over. You can also look at your current specific gravity reading. A reading of 0.998 or less indicates the wine is likely dry as well. So by tasting and testing you can get a good idea of where you are in the fermentation process. If your wine is sweet then grab your hydrometer, take a specific gravity reading, and record your results. Then wait one week and take another specific gravity reading. If: the second reading is lower than the first reading fermentation is still going (sugar is being consumed). the two readings are the same (and the wine tasted sweet) then you probably have a stuck fermentation (sugar is not being consumed). the second reading is higher than the first reading then something went wrong (sugar is being created? that’s not possible). Double check your current reading and wait another week to take the next reading. Disregard the first one. It can be quite difficult to recover from a stuck fermentation, especially if it gets stuck with very little sugar left in the wine. This is a topic we’ll cover soon here at the Academy. Cheers Barbara! -Matt Williams Additional Information Yeast Life Cycle Protecting Your Wine With Airlocks How to Use a Wine Making Hydrometer Photography by: Tim...

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Carbonic Maceration of Wine Grapes

Carbonic Maceration of Wine Grapes

Carbonic maceration is a unique method of fermenting grapes into wine. While it doesn’t completely ferment all of the sugar into alcohol, it does impart a unique character on the wine. What makes this method of fermentation so different is that you begin with whole, unbroken grape clusters still on the stems. The grapes are then placed in a sealed fermentation container filled with carbon dioxide. The carbon dioxide discourages yeast fermentation and encourages enzymes naturally present in the grape to be released. Once released the enzymes break down the sugars into alcohol. Thus the sugars are fermented without the help of any micro-organisms. What Types of Wine Are Made from Carbonic Maceration? The most notable wine produced using this method is Beaujolais Nouveau which is made from Gamay grapes. Characterized by its fruity flavors and lack of tannins, this red wine is meant to be consumed the same year the grapes are harvested. The entire process from harvest to bottling takes between six and eight weeks. Traditionally Beaujolais Nouveau is available by the end of November in America. It has become somewhat of a tradition among winos to drink Beaujolais Nouveau at Thanksgiving. Many believe that the quality of this wine in a given year is an early indicator of the quality of the entire vintage. Other wine makers and tasters alike believe this to be a bit of a stretch. Admittedly it is hard to imagine drawing any conclusions about an entire vintage based on a single style of wine that was cranked out in a matter of weeks. The Carbonic Maceration Process To pull this off successfully you’re going to need to be very careful while handling your grapes to ensure that no grapes are broken open, this is critical. Take the unbroken fruit and place it in a seal-able fermentation container filled with carbon dioxide. This is done to prevent oxidation and to inhibit spoilage micro-organisms from taking hold. With the grape clusters placed gently in the carbon dioxide flushed container seal the lid, place your airlock, and start monitoring the temperature. It takes approximately five to fifteen days for carbonic maceration to complete. During this time only about 3% alcohol by volume is produced. Thus you’ll need to follow this fermentation a yeast fermentation. A lot of heat is generated during carbonic maceration. Make sure that the grapes don’t get too warm otherwise it may take on cooked flavors. Generally speaking keeping your temperature below 90° F / 32° C will prevent this. After carbonic maceration has finished open the fermentation vessel and then crush and press your grapes to release the remaining sugars and the alcohol produced thus far. Once extracted the remaining juice should be stabilized and inoculated with your yeast of choice. Traditionally a wine made this way would not spend any more time on the skins. Sufficient color, flavor, and aroma extraction is achieved during carbonic maceration thus an extended maceration is not needed. It is also important to limit tannin extraction so that the wine may be consumed sooner. More tannic wines need more aging to become palatable. Amateur wine makers could use a plastic fermentation...

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How to Re-Hydrate Yeast

How to Re-Hydrate Yeast

Yeast, a winemaker’s best friend, and star of the show when it comes to fermenting grapes into wine. They make it all possible. With a properly hydrated yeast your fermentation will start strong and be less likely to get stuck. Which is why it’s critical to understand how to re-hydrate yeast. What is dry yeast? Dry yeast is made up of small granules that consists of live, active yeast cells enclosed in a hard shell of dead yeast and a growth medium. In order for the live yeast cells to break free and ferment your must the shell must first be broken down. This is where hydration comes in. Whether you re-hydrate yeast yourself or allow nature to take it’s course in the must what you’re doing is breaking down that outer shell. If yeast is not properly re-hydrated the individual organisms can’t function properly. Their cell walls will not be fully permeable and they won’t be able to take in sugars and release carbon dioxide and alcohol. How does yeast re-hydrate if we don’t do it? In most wine kits re-hydrating the yeast is not only not necessary, the directions clearly state “do not re-hydrate the yeast”. You just add it straight to the grape juice concentrate and water mixture. By doing this we’re trusting that the dried yeast will hydrate well enough on its own. Kit makers choose the yeast strains based on many factors but one of the key factors is its ability to hydrate on its own in the must. If you read yeast hydration instructions, however, you’ll notice that the optimal water temperature for hydration is 104-109 degrees (F). Kits instructions call for innoculation temperatures of 72-75 degrees (F). These are less than optimal conditions for the hydration of yeast which is why kits only come with certain strains. How Re-Hydrating Yeast Affects Fermentation Hydrating your yeast at 104-109 degrees (F) helps break down that crusty outer layer and allows the live cells within to break free and begin multiplying. In just a few minutes your yeast population is already starting to explode. Contrast this with pitching dry yeast in a cool must. Without that heat it takes longer to break down the outer shell. This is why you only see evidence of fermentation two days or so into the wine making process. If you re-hydrate the yeast that comes with a wine kit you’ll likely see evidence of fermentation within a few hours. The rapid population growth speeds up fermentation because there are more of the little guys sooner. Another benefit of such a rapid population growth is that the yeast can dominate the environment much more easily. Keeping undesirable strains or other bacteria from getting established in your must. How to Re-Hydrate Yeast This process can vary slightly depending on the brand of yeast and the strain. However, here is the general process I’ve followed for quite a few re-hydrations. Heat 2 cups or so of water to 104-109 degrees (F). Pour 50 ml of the heated water into a dry sanitized container. Add the dry yeast to the water and stir for thirty seconds. This breaks up any clumps so...

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Advanced Wine Making Techniques

Advanced Wine Making Techniques

Complexity in wine separates the great wine from the rest. Creating a complex wine, however, requires the use of advanced wine making techniques. Here are three techniques you can start applying to your own wine making to take it to the next level. It doesn’t matter if you’re making wine from a kit, frozen must, or fresh fruit. Techniques for Making More Complex Wines There are several things you can do, even with a kit, to improve its complexity. Simply put, complexity is a function of nuances in flavor and aroma. Single variety wines, while flavorful and tasty, tend not to be very complex. Their flavor profile is simple. Let’s look at some methods to add complexity to our wines. Split Fermentation Yeast imparts flavors and character in your wine as it turns the sugars into alcohol. Different yeasts produce different flavors. Thus one way you can make a more complex wine is by fermenting half your wine with one yeast and the other half with another. You’ll have to do a bit of research to determine what yeasts work well with the grape varietal you’re working with. To do this you’ll need two fermenters, two carboys, and all the necessary airlocks. You can use the yeast your kit comes with for one half and pick up another strain for the other half. Mix Different Types of Oak Oak is considered to be the winemaker’s spice cabinet because of all the different flavors that it contributes. Another way to add complexity to your wine is to combine oak from different places. For instance instead of just using the oak that comes with your kit pick up some American and French oak cubes and combine them. American oak tends to be more bold while French oak is more subtle. Combining the two at varying ratios can offer a lot of complexity. Pier Benci, an Italian wine maker, offers his preferred ratio as 30% American oak and 70% French oak. Likely the American oak is used in less quantity so it doesn’t bury the French oak. Hungarian oak is another option. Also, if you’re using carboys instead of barrels you’re free to experiment with other types of wood altogether. Blending Different Varietals The blending of wine is a long standing European tradition. Taking various amounts of different varietals, sometimes up to five or six, to creating one wine adds a tremendous amount of complexity. Nuances from each varietal all acting together to create one masterful glass of wine. Blending is done with finished wines by experimentation. Take a base varietal such as Zinfandel. Then create a mixture of 75% Zin and 25% Merlot for example and see what happens. Try several different blends and ratios until you find one that really speaks to you. Test your blends by the glass before mixing all of your wine. Find the ratios you like and then bottle the blended wines. This is where wine makers start to earn their status as artists. Blending is done with only the best of each varietal. They do not try to use up a sub-par wine by blending it with...

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The Most Neglected Piece of Winemaking Equipment

The Most Neglected Piece of Winemaking Equipment

It’s inexpensive, easy to use, and easy to neglect. The cost of neglecting it, however, is all the wine your making. So what is this little savior of wine? The airlock. Why Are Airlocks So Critical? First, they keep out all of the undesirable micro-organisms that seek to ruin your wine. Vinegar bacteria, lactic bacteria, and weak wild yeasts are all kept at bay with a properly maintained airlock. Second, airlocks prevent oxygen from entering your wine. Not only does this prevent oxidation it makes the production of alcohol possible. As I mentioned in my post about the yeast fermentation process, yeasts only produce alcohol when it consumes sugar. This is only possible once they’ve run out of oxygen. Thus it is critical that a properly set up airlock is used to starve the yeast of oxygen so they’ll produce alcohol. Now that I’ve shown you how important it is to properly setting up an airlock let’s get into how to set one up. Why do Winemakers Neglect Airlocks? Airlocks are put in place when the wine needs to sit for a while. Generally they’ll be in place for as little as a couple of weeks or up to a few months or more. Many winemakers will “set it and forget it”. The hard part is done and now it’s time to give our wine a little time to itself to ferment or age. Many will just walk away and trust that it’s functioning properly and nothing will happen to it. However there airlocks can fail. All it takes is an overly active fermentation, an improperly seated plug, or a cat to make unseat an airlock and let int oxygen and some nasty micro-organisms. When that happens all that wine will have to go down the drain. How To Use an Airlock In the following four minute video I’ll walk you through the entire process of setting up your three piece airlock. These are not the only type of airlock on the market, however, they’re the ones with the most moving parts. Watch this video to make sure you set up your airlock properly. If you follow these steps you’ll be well on your way to making the best possible wine with whatever raw materials you started with. The price for not following these steps so is just too high. Pretty easy right? Yes, BUT, don’t take these little devices for granted! They may be simple but they’re our guardians against spoiled grape juice. Remember These Tips Clean and sanitize every part of the airlock and plug. Fill airlocks with only clean water. Check on your airlock every day! Here’s a link to the same three piece airlock I use to make my wine. This is an affiliate link so if you use it you will be helping to support Winemaker’s...

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