Colloidals and filtration

Colloidals and filtration

NTU in filtration

the clarity (unity=NTU) is measured by how much light is passing through a certain amount of liquid. It see suspending particles in the liquid but doesn’t say how big they are…. Roger Boulton published in 2001 an article « fouling of wines on membrane filter is not related to the clarity » it show studies who demonstrated wines at the same turbidity who are not fouling filter in the same way or higher NTU is fouling less the filter than smaller TNU in some case. It depends of their compounds. For example, if they are very thin and in hight number, they will build a more compact layer as retenante than bigger particles with less quantity. It is a bit like clay and sand. Sand will still let pass through where clay doesn’t. But in the bottle they can have exactly the same clarity depends of quantity. The problem are the colloidals in the wine.

Enzyme friend of filtration

Enzime can be part of filtration process, and because it is chemistry, it sound way more exiting than filtration to me. Sure people get very chill about enzyme as it can change the taste of the wine very easily but depend the type and the quantity used. Most of enzymes are naturally on the vine and it can be the wine when the grapes are crushed with stems.

Polyphenols can basically connect with other things. They build chains and hold goodness as retentates when normally those would pass. In some case it is possible to push them through with a bit of pressure but it is not ideal, and it can strip out the wine. Sometimes just the time break them apart but it can build up again later. Enzyme is the third option.

Some varieties can be very rich on colloidals, and it is obvious than this problem will appear. So an addition before alcohol is created, would make it more efficient. If the fermentation already started, then the addition will be after as it drop the yeast out. Some type of colloidals can also appear during malolactic fermentation. They seems to come out easier when they are at cold temperature

Enzymes can change the taste as it is changing the structure of the wine (not always in a bad way!), it also need time to stabilize. It can happen than the wine change and look strip out, but few week later, good flavors can express their-self again… Once the structure been change, the NTU can goes up but the filtrability is way better.

I still think NTU give a brief idea of which filtration type to use (if we have options), however colloidals can surprise us and make filtration harder.

Podcast

https://www.insidewinemaking.com/#/097/filtration-maria-peterson/

AWRI ( 2017) Factors affecting wine texture, taste, clarity, stability and production efficiency. Retrieved from:  https://www.awri.com.au/research_and_development /rde-plan/projects/project-3-1-4/  

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