Settling Solids Prior to Fermentation


Once we finish pressing we will have a light green/yellow colored juice that will be very cloudy. This cloudiness is coming from fine grape particles/solids that have been created during the crushing-destemming and pressing stages. Removing these solids is highly recommended  because doing so dramatically lowers the production of heavy, harsh, green/herbaceous, and sharp notes from potentially developing in our white wines during the fermentation. When the solids are removed we get cleaner, more aromatic and fruity wines. Quite simply: a clean juice makes a clean wine.

However, there are some technical requirements that may not make this a viable option for everyone. Settling our juice takes time and is only possible if we can ensure that during that time required to settle-out the solids our juice can be protected from oxidation and contamination from unwanted yeast and bacteria. In order to establish this protection we will need to be able to ensure the following:  

  • Correct, immediate SO2 additions are made at the crusher-destemmer at regular intervals (see our Guide to SO2 Management).  
  • If the juice will be exposed longer than 4 hours before being inoculated, (starting from when the juice is first exposed to the air) the temperature of the must should be kept at ≤ 50-55 F (closer to 50 F is better than 55 F) to delay microbial growth and slow oxidative reactions. Besides the danger of undesirable flavors and aromas being created in our wine by unwanted yeast and bacteria, the bubbling action of an active fermentation will effectively keep the solids in suspension and they will never settle out! 

Note: A couple of ways to maintain cool temps are: chilling the fruit before processing (if you are working with your own vines or are close to the vineyard then harvest and process in the early morning); use a series of sanitized ice jugs submerged in the must during the settling period; settle carboys/covered buckets in a fridge; work in a cool cellar (air-conditioned/glycol).  

  • The juice should also be protected from oxidation with a blanket of inert gas during the entire settling process (for more info on inert gas, see our Guide to Inert Gas in Winemaking)  
  • Lallzyme-C MAX (AD354) is a pectolytic enzyme preparation that was specifically designed to speed up the settling process. Typical results see clearing in 4-6 hours, even in difficult conditions, such as low pH, low temps, high pectin content.

NOTE: It is important to understand that any benefit that might come from allowing the solids to settle out of the juice is negated if a wild fermentation starts in your must and the solids never settle out due to the swirling/churning action of an active fermentation. If you are not able to keep the must at 55F or lower for the couple of hours required to settle out the solids then we recommend skipping this stage. In this case just go ahead and adjust the pH/TA and Brix right after you press and then add your yeast as soon as possible.

Once the settling has finished, you will have a layer of a light beige colored sediment at the bottom of the vessel and a layer of clear juice on top of it. The clear juice will need to be transferred off of this sediment layer into a clean vessel. This is called "racking" and can be done by using a gravity siphon set-up for small vessels (carboys and demi-jons), or with a pump. If you have access to inert gas it is highly recommended to purge the receiving vessel before it gets filled to eliminate the oxygen and avoid any oxidation reactions (For a complete explanation of transferring wine, see our Guide to Transferring/Racking).   

Note about sanitization: At all stages in the winemaking process any tools and equipment that are going to come into contact with the juice or wine will need to be sanitized. This is done to eliminate spoilage yeast and bacteria that could contaminate our wine and ruin it. Sanitization is done in two steps:

  1. Make sure the surface area to be cleaned is free of any dirt, film or grime. If it isn’t you will need to scrub it off with a sponge or scrub pad and water. Brushes and hoses can be cleaned with a long hose/line brush made for this purpose.  
  2. Once the surface is clean it can now be sanitized. This is done by preparing the sanitizer* and pouring, wiping, or swirling to make sure the sanitizer wets all surfaces needing to be sanitized. After a few minutes contact time, rinse the equipment off with fresh, clean water.  

* We recommend using Star-San (CL26) as your sanitizer, as it is much friendlier and easy to deal with than the traditional SO2 and citric acid solution that is often referred to in many winemaking books. Unlike the SO2 solution, Star-San has no dangerous fumes and is perfectly safe to come into contact with. In fact during our winemaking, often the first step when we begin working is to dunk our hands into a bucket of prepared Star-San!

The clear juice can now be adjusted for pH/TA and Brix and fermentation initiated (see our Guide to Testing Wine Must), or we can choose to carry out one additional processing step and preemptively remove some of the browning agents and a portion of the protein before they can cause us problems later!

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