SO2 Management for a barebones beginner?

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AcidicOtis

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Hi all.

I am a college student, I could spend the money but I have already spent so much on just chemicals, grapes for wine, vines for a bitch-vineyard, etc. I saw some free SO2 tests on the internet but they are like $40 for 10 tests with a shelf life of like 4 or 6 months. I do not make wine this frequently and I do 1 gallon fermentations just to learn from my mistakes. I've had a couple batches where I swear oxidation occurred. I just do not want etOH -> CH3CHO as I do not want those smells or sweet tastes. I have a Norton batch right now that has been sitting/clearing for a nice amount of time (months). It tastes alright for the most part, a bit acidic, but comes with the nature of the grape. Anyways, I definitely do not want that shit to get ruined by oxidation. Anyone know of a way to manage SO2 levels in wines without spending a bunch? Much appreciated!
 

AcidicOtis

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so standard is 50 ppm = 50 mg/L * 3.79 L (for 1 gallon) = should add 189.5 mg to get a desired approx. 50ppm, thanks
 

sour_grapes

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Yeah, you may be overthinking this. I don't test my SO2 levels. (Not that this is something to aspire to!) You could follow the rule of thumb that salcoco mentioned. Many of us just blindly put in 1/4 tsp for a 5 or 6 gallon batch every 3 mos.

What is a bitch-vineyard?
 

AcidicOtis

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Yeah, you may be overthinking this. I don't test my SO2 levels. (Not that this is something to aspire to!) You could follow the rule of thumb that salcoco mentioned. Many of us just blindly put in 1/4 tsp for a 5 or 6 gallon batch every 3 mos.

What is a bitch-vineyard?

Oh lol. Okay that is fine, I am writing my senior seminar on winemaking and how the chemical/flavor profile can be altered by different strains of yeasts and saw that SO2 was important, something I haven't been very rigorous on. I didn't want to add too much to avoid any SO2 bleaching of the anthocyanins in the wine, but I am thinking those are all bound to protein or have formed polymers. I don't know. A bitch-vineyard, I just mean I put in umm... 25 plants. Going to start to build my trellis system this year. They were planted last year. lol thanks for your contributions!
 

stickman

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@Tyler Obermark Your calculation is wrong depending on how you apply the number. Potassium Metabisulfite is considered 57% SO2 by weight, so you need to divide your answer 189mg by .57 which gives about .33 grams for 1 gallon. As indicated by others above, the 1/4tsp for 5 or 6 gallons works fine.
 

AcidicOtis

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@Tyler Obermark Your calculation is wrong depending on how you apply the number. Potassium Metabisulfite is considered 57% SO2 by weight, so you need to divide your answer 189mg by .57 which gives about .33 grams for 1 gallon. As indicated by others above, the 1/4tsp for 5 or 6 gallons works fine.

Nice... I found this nifty doc with basically what we figured out here.. At 50 ppm SO2 that is like I had about .186 g and for K metabisulfite is about 0.32 g... adds up good. thanks

 

Rice_Guy

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The pigments in grape seem to be stable with exposure to metabisulphite, as a contrast situation cherry bleached out when I sprinkled meta on fruit from the freezer without first adding water.
Like sourgrapes, I did not have the ability to test for free SO2 for years, now that I can test I see country wines/ white wines consume free SO2. The quick and dirty rule is to assume it is at zero and add accordingly. The polyphenols in red grape are good antioxidants therefore the “new to wine“ recipes seem reasonable. I have even had organic/ no meta red wine which was pretty good.
Another trick is masking,,,, sugar, acidic flavors as apricot, finishing tannins.
 

NorCal

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If you are writing a Senior paper on wine making, my advice is that you should start with the basics; measure specific gravity before and after fermentation, pH, proper O2 free storage, follow sanitization protocols. Study SO2, why you use it, what it does and how much to use. If you don’t make a clean wine, you won’t know the effects of other variables.
 

AcidicOtis

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If you are writing a Senior paper on wine making, my advice is that you should start with the basics; measure specific gravity before and after fermentation, pH, proper O2 free storage, follow sanitization protocols. Study SO2, why you use it, what it does and how much to use. If you don’t make a clean wine, you won’t know the effects of other variables.

No, it isn't on the process, it's more of the effects that studies have found onf the chemical profile of finished wines by different non-Saccharomyces yeasts like L. thermotolerans, S. pombe, O. oeni (MLF), & a few others. Yeah, I just mean my paper on SO2 seemed to have some effects on bleaching (which was found to be minimal) but also its antioxidant properties which is the biggest reason I would want to use it. I think the question is well answered now. Thanks!
 

NorCal

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No, it isn't on the process, it's more of the effects that studies have found onf the chemical profile of finished wines by different non-Saccharomyces yeasts like L. thermotolerans, S. pombe, O. oeni (MLF), & a few others. Yeah, I just mean my paper on SO2 seemed to have some effects on bleaching (which was found to be minimal) but also its antioxidant properties which is the biggest reason I would want to use it. I think the question is well answered now. Thanks!
Like most answers in wine and poker, it is multifaceted. SO2 serves as both an antioxidant as well as an agent to combat microbes. This protective system in wine is a joint effort between the pH, alcohol, tannin and free SO2 in the wine. We strive to minimize the SO2 in the wine by taking into account the other components in the wine, coupled with the expected time before the wine is consumed.

I am concerned about different things in a wine, starting from the beginning. Was the fruit clean, or was there bird or deer damage, mildew, bunch rot. Did the ferment struggle, did it run hot and fast, were there off odors, If it struggled with the fruit or ferment, I’m heavy handed on the racking, SO2 and oak. If all is nice, it gets kid gloves, with minimal racking, minimal SO2 and is treated to a light toast of French oak.
 

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