Mold & Sulfite Testing

[Grancru]

On March 19th I added 1/4 teaspoon of potassium metabisulfite into the bottom of a sanitized carboy
and racked my three 5-6 gal carboys onto it to fend off a mold.

On April 18th I racked and added 3/8 tsp myself per 6
gallons as the mold persisted.

I just used a CHEMetrics Titrets kit to test and have a reading approx. 35 yet there is a very small substance slowly forming on the little surface area in the neck of the carboys.

Is this something I should worry about at this point? Is the 35 reading acceptable or should I add more sulfite and retest?

 

[vcasey]

Could you tell us when you started the wine, what was your process, did you stir the fruit, did you stir the mold into the must, what kind of fruit? Perhaps then someone could help.

 

[grapeman]

Yes some more information would be good. What was it, fruit or kit? Why do you think it is mold? Please describe it. 35 ppm free S02 should keep any nasties at bay.

 

[Grancru]

<div style=": left; overflow: auto;" ="msg">This fall (9/26/10) I
crushed 6 cases of cabernet sauvignon grapes, fermented, pressed and the result
was 23 gals. of wine.

It has been bulk aging ever since in 2 - 5 gal and
2 - 6 gal carboys. No sulfite was ever added per the "old Italians" where I bought the grapes and so far it tastes
great.

I do not have any OG readings or prefermentation test numbers or but
the FG was 1.00 when I racked it off the lees. I let it sit for another month
and racked it again.
<div style=": left; overflow: auto;" ="msg">
I have never done a malolactic fermentation and was
simply following what the old timers told me to do that sold the grapes. I am beginning to see there may be a lot more I should be doing but need some
direction.
None of this was necessary with he Meads I make.

I posted photos on my thread about degassing on this forum and the conclusion was it is mold. I have racked off the mold a couple times sulfiting as described above.

I hope this helps.

 

[Rocky]

Grancru,
How large were the cases of grapes, that is how many pounds of grapes did they contain? Long ago we bought 44 lb. boxes and used to get 3 gallons per box in a good year. Later, the growers in California reduced the size of the box to 36 lbs and we would get something less than 3 gallons on a good year. From what you are saying, you got almost 4 gallons per case. Wow!

 

[Grancru]

These were 36 lb cases of Top Brass grapes from California Wine Grape Co. in Detroit @ $1 per lb. It was actually 7 cases as I look at my receipt.

 

[Rocky]

Grancru,


That is still a very good yield and not a bad price for the grapes. Good for you!

 

[robie]

I know this is a fresh grape issue, but for those of you who make kits, remember the problem Cellar Craft was having with their big red kits, which contained that gooey grape pack? They had a milky substance form on top. Of course it wasn't exactly mold, but maybe Grancru is having a similar problem with his fresh grapes and it is not really mold. With his free SO2 levels where they are, it doesn't seem there could be any mold.

Cellar Craft provided a special enzyme packet that would take care of the problem.

Maybe George here at Fine Vine Wines could give some advice. Give him a call. I believe he can get the enzyme packets.

 

[grapeman]

I know a lot of Italian winemakers never use sulfites, and this is an issue casused by the lack of the sulfites. I'm not sure what you are seeing, but it is probably not mold. I would continue to rack it periodically and keep checking sulfite levels. Around 50 ppm free S02 should give adequate protection for the wine. When it gets clear and tastes good, and after checking that you are in the 40-50 ppm range, I would bottle it and be done with the problems. It should be fine at that point. If there are additional problems, remember to begin adding sulfites sooner next time. The old fashioned way worked for many, but not everyone and there were bad batches encountered from time to time. Sulfite from the start and ensure a good batch from the beginning.

 

[Grancru]

My reading is approx. 35 ppm free S02. The test kit says "As a rule, a test result of greater than 40 ppm free sulfite for any wine should be considered suspect".

You state it should be in the 40-50 range which goes against what the test kit states. Am I missing something?

 

[Wade E]

I keep my whites around 40 and my reds around 35. Do those instructions state anything further on what they think it the free S02 should be?

 

[Grancru]

No, it doesn't and when at the brew shop the owner went through some books and couldn't find anything.

 

[Dean]

Remember that the effectiveness of free SO2 in anti-bacterial settings is also directly proportional to your PH levels. the lower the PH level (stronger the acid), the less FreeSO2 you need to protect. Oxidation binding with FreeSO2, of course has no bearing on PH level.

 

[grapeman]

That is a good point Dean. Grancru do you know what the pH of the grapes were or the wine is now? Being Cab Sauv, they could be in the mid to upper 3.x range whcih would require a greater amount of sulfite to provide protection. With a low pH wine, 35 ppm would give protection, but if in the 3.8-4.0 range even 50 ppm would not likely protect it well.

 

[Grancru]

I do not know what the pH is. I can taste the acid but as to a true level I do not know.