Sulfite Sanity Check

Discussion in 'Yeast, Additives & Wine Making Science' started by FunkedOut, May 5, 2019.

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  1. May 5, 2019 #1

    FunkedOut

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    Still waiting on my first wine kit to arrive. Hopefully, it will be here next week.
    In the meantime, I’m planning out my process and wanted to get a sanity check on my understanding of sulfite additions.

    Making this wine from a kit, I’ll assume the juice and skins are already treated and ready to go.
    I’ll not worry about adding any K-meta until after fermentation is complete and the wine is dry.

    The kit instructions direct the addition of however much sulfite they include after degassing and racking.Then wait 4-6 weeks, rack and bottle.

    My goal here is to understand the science, rather than simply making wine.
    Let’s assume the kit targets 30ppm of free SO2 with that addition.
    If I bulk age the wine in the carboy for 6 months before bottling, how much free SO2 would be safe to assume is lost?
    Is free SO2 lost over time, or mainly due to racking/oxygen?
    If there’s a good way to get by without a SO2 test kit, I’d prefer to save that expense until later.

    Also, if I take a slow approach to degass the wine with a vacu vin and time, would I be safe to spend a few months without any sulfite additions post fermentation?
    Or would the initial K-meta addition following the fermentation/racking be prudent?

    Thanks in advance.
     
  2. May 5, 2019 #2

    salcoco

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    while bulk again the free so2 from the addition of K-meta is bound and thus reduced. within 3 months or less the free so2 will be in the twenties or less assuming you started at 50ppm. 1/4 tsp powder k-meta in 5 gallons will usually give 50ppm with a ph as high as 3.5. so2 is a oxygen scavenger as well as a bacterial inhibitor. so chemical reaction and racking can cause it to be reduced in the wine. I usual follow this schedule fermentation complete rack to a carboy, after thee days rack off of lees add so2, after two weeks rack of off fine lees add so2, after 3 months and every three months after rack(optional) add so2 not optional. if you follow the 1/4 tsp dosage you will not need a test kit, over thirty years I purchased just about any test kit or equipment necessary to measure so2 and found that they gave you a lot of information but the 1/4 tsp dosage worked just as well.
     
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  3. May 7, 2019 #3

    FunkedOut

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    Obviously, a test kit for free SO2 is the only way to be sure.
    But all of my reading and, I think your post, converge on the same advice.
    Target a 50ppm addition after secondary is complete and racking into a fresh carboy.
    Target a 50ppm addition after every 3 months of bulk aging.

    Most concrete data I found was in this post by @ibglowin :#24
    He added an initial dose of K-meta after fermentation, then a 1/4 tsp dose 3 months later.
    After a second 3 months passed, no addition and bottled the wine.
    He measured the free SO2 at 28ppm.

    What is the target for bottling? 50ppm? 30ppm?
    Get the bottling done that same week as the last addition? Same month? At the end of the 3 month cycle with no addition?
    The kit instructions suggest bottling 4-6 weeks after the initial sulfite addition of (at this point) unknown ppm target. I will weigh the sulfite addition included in the kit when I receive it.
     
  4. May 7, 2019 #4

    ibglowin

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    The target depends on the pH of your wine. The higher the pH the more sulfite needed to protect the wine down the road. The lower the pH the lower the amount of sulfite needed.

     
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  5. May 7, 2019 #5

    Johnd

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    @FunkedOut ,it also depends upon the wine type, red or white. Below is a handy dandy little chart that you can use to look up your SO2 target based upon the criteria.
    A600CC22-BEA6-473E-BA06-893E59526ECC.jpeg
     
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  6. May 7, 2019 #6

    FunkedOut

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    This is great info. Thanks!
    I have a decent pH meter I can use. That should make the target level very clear at each addition.

    The assumption I will make moving forward will be that 3 months of sitting in a carboy at 70*F will lose 30ppm of free SO2. That should get me by until I decide to buy a test kit.
     
  7. May 7, 2019 #7

    NorCal

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    Wines will consume the SO2 a different rates, depending on a number of factors. One of the key ones is the storage vessel. I have a Vinemetrica and measured the wine in barrel, in flextank and in a barrel over the same period. I’m sure I posted here 5 or so years ago. The barrel consumed the SO2 twice as fast as the glass carboy and the flextank was between the two. The amount being consumed will also depend on your dissolved oxygen in the wine, your bung and of course how often you are opening it to take a taste.
    Assuming the pH is 3.5 or less, I’m comfortable adding the 50 ppm on the schedule and only measuring every other addition, it’s usually close enough.
     
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  8. May 7, 2019 #8

    salcoco

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    I agree I followed the fancy graph and the fancy measurement and it all came down to is just follow a schedule. 50ppm should be the target for bottling. I bottle right after an addition even if I just racked two months previously. If you feel more secure go ahead and measure and it will give you the experience of recognizing measurements are great but as in playing horseshoes the schedule is close enough.
     
  9. Jun 16, 2019 #9

    FunkedOut

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    Planning on racking into a fresh vessel in the next couple of days.
    I thought I had the K-meta figured out, but my understanding conflicts with the kit instructions so I would really appreciate a sanity check.

    I have a decent pH meter and plan to measure the wine after racking, but lets assume 3.5 for the sake of this exercise.
    Using this calcualor: https://winemakermag.com/resource/1301-sulfite-calculator
    [6 gallons, 3.5 pH, 15.3% ABV, 69*F, 0.5mg/L molecular]
    The recommendation is 15 mg/L (ppm).

    Q1 - The text on that same page recommends 100% adjustment for a wine with these parameters which doubles the recommended dosage. Where on the 0-100% spectrum should I land?


    Say we decide on the max of 100% adjustment, and aim for 30ppm. That is equal to 1.2 grams of K-meta powder.
    The kit came with 4.8g of K-meta powder and the instructions say to add it all on this next racking, after degassing. That would yield 120ppm.
    The kit also includes K-sorbate but I will be skipping that.
    The instructions continue by adding clearing agents (Kieselsol and Chitosan) and allowing 28-42 days to go by before racking and bottling.
    Here's the ringer, the kit says, "If aging in bottle past 6 months, we suggest adding an extra 1/4 tsp of [K-meta]."
    If 1/4 tsp = 1.4 g, then that's another 35ppm, for a total of 155ppm inside the first 3 months!

    My plan was to add the 1.2 g (aiming for the 30ppm) now at this racking.
    Allow the 28-42 days of clearing to happen.
    Add another 1.2 g at that racking, and every racking at 3 month intervals.
    Bottle the wine almost immediately following (within a week) one of those rackings/dosings, once the wine has spend a 3 month cycle with no sediment.

    Q2 - Is my plan a safe one? Or should I stick to the kit instructions here?


    Thanks for taking the time to read and respond.
     
  10. Jun 16, 2019 #10

    Johnd

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    Here’s my two cents:

    Follow the kit instructions in the early stages (fine to skip sorbate), adding the prescribed package of sulfite after AF racking. Degas, add clearing agents, wait for wine to clear, rack to a clean vessel, then age in the carboy a few months.

    At the three month mark (since you added your first sulfite dose), dose again, this time, you can use your meter and chart to determine your own dosage. Your plan from here on out sounds reasonable, provided your wine is free of CO2, you’ve finished oaking, and you are 100% happy with the taste.

    I use the chart above and fermcalc to do all of my dosing (after the initial 1/4 tsp / 6 gallons. Sometimes the 1/4 tsp is heavy handed, but in a brand new wine, full of O2, it gets used up pretty quick. See the chart, the recommendation for a 3.5pH red wine is 25 ppm.
     
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  11. Jun 16, 2019 #11

    ibglowin

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    The reason you get 5 gm of KMETA in a kit is that on your initial dose you have lots of O2 in your wine and that will suck up quite a bit of your free SO2 almost immediately. After that initial dose not so much O2 floating around so more of your KMETA will be hanging around for a longer period of time and available to protect your wine down the road (assuming your properly topped up and stoppered)

    As has been said. Follow the instructions.
     
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