Other K- meta

[blkcloud63]

Hello, I’m getting ready to start my first journey in aging a red wine kit in a carboy. My understanding is you should add K-meta every three months. If there is sediment rack otherwise just add 1/4 tsp. If I’m correct if there is no sediment do I just sprinkle it into the carboy? Should I stir? Or should I take a sample and mix it into the sample and then add it back in without stirring? Or rack every three months putting in the K-meta first? Please share your practices Thanks in advance.

 

[cmason1957]

My answer is Yes. (I think I have done all three or four of those things). I don't base my rackings on is there sediment or not, but more on what kind and thickness of sediment there is. Generally, by the time of bulk aging for me, I have just light, thin sediment and I don't rack, but pull off a small amount of the wine, add K-Meta to that and pour in or just add the K-Meta and give it a stir. If the lees fell out before, they will fall out again.

 

[winemaker81]

I concur with @cmason1957. By the time I move into bulk aging, the gross lees (fruit solids) is gone. I may have a thin layer of fine lees (yeast hulls) which I ignore. Wine has no convection currents, so stirring is necessary to distribute K-meta.

At my last racking prior to bottling I hold the racking cane off the bottom, so I get 24 clear bottles from a 19 liter carboy. The remainder may go into the fridge to clear, or I may simply ignore a bit of sediment. Think of it as a pro-biotic dose.

 

[Swedeman]

Wine has no convection currents

Well, there are movements, called diffusion. There will be a movement (a "random walk" by the molecules) from an area with a higher concentration to an area with a lower concentration until the concentration is the same throughout the liquid and equilibrium is reached.

Having said that, given the time scale, stirring is needed as @winemaker81 says. I don't know the diffusion constant for metasulphite but it will take a sucrose molecule roughly 2 years to move 50 cm by diffusion only (using Einstein's approximation equation).

 

[Rice_Guy]

My practice:
opening the carboy introduces oxygen which is concentrated on the surface/ ullage. I sprinkle powder on the surface since that is where the biggest oxidation risk is.
I do not open every three months, I will open a carboy only if there is a processing purpose as racking off the lees or prepping for bottling
I will do mixing at bottling time by pulling a vacuum and letting the bubbles create turbulence
I currently use a solid bung on anything that is eleven or even nine months old, CO2 is my friend
prior to bottling I will pull a vacuum on the carboy with a check valve (like a head space eliminator) roughly every half hour for a day, I monitor the rate of vacuum loss as a measure of how well the wine is degassed
micro oxidation, leakage of oxygen with natural cork closures is useful with red grape wines (5 to 7 mg O2 per liter per year), I am debating if I should be keeping as reductive a beverage, or add tricks that slowly leak oxygen in

there are sulphite calculators on the web which give desired dosage rate based on free SO2. I am curious if anyone on WMT has a data set of what the free SO2 loss rate is, ,,, I sin since haven’t collected my own data on rate of decay, I simply assume it is zero free SO2

 

[winemaker81]

there are sulphite calculators on the web which give desired dosage rate based on free SO2. I am curious if anyone on WMT has a data set of what the free SO2 loss rate is, ,,, I sin since haven’t collected my own data on rate of decay, I simply assume it is zero free SO2

Given that SO2 binds to contaminants, I expect the loss of free SO2 is more related to the level of contaminants in the wine. Does SO2 breakdown on its own?

 

[Rice_Guy]

SO2 is in a reduced state capable of donating electrons to any number of organic molecules (wouldn’t call them contaminants, just soluble grape flavors), ,, wine has lots of organics and even H2O which are energetically ready to accept electrons so it looks like SO2 breaks down by itself. Some of the reactions as water are reversible and can be driven either direction by decreasing the pH or adding an alkali. This is reflected in a 50% of the molecule conversion point which is called pKa, ,,, the pKa equals 1.81 , ,,,, and this is a long explanation of why we drop the pH with citric acid in sulphite sanitizer.

SO2 as a pure gas is stable for years.

Given that SO2 binds to contaminants, I expect the loss of free SO2 is more related to the level of contaminants in the wine. Does SO2 breakdown on its own?

There are reactions that the organics undergo with time so there is a gradual increase of redox potential and decay of free SO2. ,,, should add we try to avoid heavy metals as copper since they catalyze breakdown.
As a practical point you and I breath oxygen so there are lots of molecules ready to accept electrons, ,,,, and metabolism is converting food which can donate electrons into ADP which the cell can use for energy.

 

[silverbullet07]

If you add a full k-meta dosing at racking but end up racking two weeks later, do you hold off adding more k-meta until the 3 months when you may rack again or do you do a 1/2 dose or 1/4 dose since you had to rack it.

 

[winemaker81]

If you add a full k-meta dosing at racking but end up racking two weeks later, do you hold off adding more k-meta until the 3 months when you may rack again or do you do a 1/2 dose or 1/4 dose since you had to rack it.

I do a full dose at each racking.

 

[silverbullet07]

I do a full dose at each racking.

Thank you. How many doses would it take to start getting to much. I know I need a SO2 analyzer kit but it is hard to justify the cost. Their expensive.

 

[winemaker81]

Thank you. How many doses would it take to start getting to much. I know I need a SO2 analyzer kit but it is hard to justify the cost. Their expensive.

A lot. Keep in mind that when you add the 1/4 tsp to produce 50 to 60 ppm in 5 to 6 gallons, within a short period of time, the free SO2 is down to 25-35 ppm, as it gets used up. Free SO2 binds to contaminants, which is why we add it.

Unless you are racking monthly for a year+, you'll come no where near adding enough K-meta to be noticeable.

I don't do SO2 testing. The 1/4 tsp per 5-6 gallons was determined through decades of practical experience prior testing being commonly available. I looked at the price of the tests and asked myself what different testing will make in my process?

 

[silverbullet07]

I agree. Thanks so much. I was just afraid to get to much but I would never rack that much. . Thanks!