Flotation: the Evolution of a Tradition

Must clarification is an indispensable step in grape processing, as well as being fundamental to the onset of proper alcoholic fermentation.

In recent years, winemaking processes have become much more refined. These processes are constantly evolving due to increasingly cutting-edge technologies and a continuous growth of information from those in the industry. The goal is to clarify must by separating suspended solids, such as residual skins and pectins, to achieve a well-defined solidliquid separation.
This can prevent the solids from releasing undesirable substances (tannins and herbaceous aromas, for example) during fermentation. Clarification of must can be accomplished through two processes:

Static Clarification

Flotation

The purpose of these practices is identical: separation of the liquid phase from the solid phase. Using the former technique, solids will settle at the bottom of the tank at a controlled temperature. With flotation, solids will be pushed to the surface, creating a layer of lees at the top of the tank.

The principle on which cold static clarification is based, is to make solid particles stick together causing them to aggregate then settle. In flotation, a gas is injected into the tank so solid particles are trapped by it and rise to the top forming a compact layer; however, this reaction occurs only under certain physical and chemical conditions.

Certain conditions must be met for flotation to occur:

1. The temperature of the juice must be between 12-20°C (53-68°F) since, at higher or lower temperatures, the density of wine changes.
2. Pectins must be small enough to adhere to the gas bubbles, so it is very important to use specific enzymes such as EnartisZym RS and perform pectin tests.

3. Subsequent additions of clarifying agents should not make gas particles too heavy, as too large or heavy floccules tend to precipitate. In which case, it is recommended to reduce the dose of protein clarifiers to decrease the size of the floccules.

4. It is a matter of timing: Grape juice must be flocculated before too many lees settle on the bottom of the tank.


How to Perform a Pectin Test?

Materials:
– Ethyl Alcohol
– Hydrochloric Acid 37%
– Test Tubes

Procedure:
– Prepare 1 liter of 96% v/v acidified hydroalcoholic solution: 950 mL ethyl alcohol, 5 mL 37% hydrochloric acid and bring to volume with demineralized water.
– In a test tube, mix 2 parts of the acidified alcohol solution with 1 part must/wine.
– In a wine rich in pectins, pectin gel with a milky color is observed.
– In a wine low in pectins, a slight cloudiness is observed.

Juice with residual pectins

Juice without pectins

Pectin test. Above 3 examples of must rich in pectins where reaction with hydrochloric ethanol is observed. The below image represents a negative test or “depectinized”.

Enartis solutions to improve the flotation process

Selecting the correct enzyme plays a key role as it is the first step during flotation.

  • EnartisZym RS is a liquid enzyme rich in pectolytic and hemicellulasic activities, which is also suitable for use in musts that are particularly rich in pectins and, therefore, difficult to clarify. Once the enzyme has been added to must, homogenize in the tank and wait about a couple of hours depending on the temperature and amount added. This enzyme degrades pectins so that the floccules formed by the addition of protein and gas can rise to the surface quickly.

Enartis offers an entire range of plant-based clarifying agents for varying enological objectives: The PLANTIS Range.
When discussing the addition of proteins to must for clarification, we usually refer to protein-based clarifiers of animal or plant origin that are intended to clarify must, improve filterability, and prevent the appearance of cloudiness and abnormal odors/flavors.
In recent years, the increasing focus on sustainable solutions and demand for vegan alternatives has led to the increased use of plant-based protein clarifying agents with the goal of achieving the same, if not better, results than animal-based products.

Enartis’ constant commitment to R&D and the search for processimproving solutions has resulted in a product with excellent clarification capabilities, suited to make flotation even simpler and more effective.

  • PLANTIS L is composed of the highest performing pea protein produced to date. Its specific hydration process increases its surface charge allowing for particularly high reactivity of the protein, enabling the product to have the best performance.
    Its liquid format makes it easy to use in the winery, without the need to be dissolved in advance. This makes it particularly suitable for flotation, where time is a decidedly relevant factor.

PLANTIS L benefits:

  • Greater efficiency in forming floccules that retain gas bubbles
  • Ensures speed during clarification
  • Excellent compaction of lees
  • Due to the nature of the pea protein, it helps decrease metal content and in the removal of oxidized and easily oxidizable phenolic substances, resulting in a longer shelf-life of the treated wine.

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Enartis S.r.l.

Via San Cassiano, 99
28069 San Martino, Trecate NO

Tel +39 0321 790 300 | Fax +39 0321 790 347
vino@enartis.it

Enartis S.r.l. – Società Unipersonale
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Società soggetta all’attività di Direzione e Coordinamento
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