mold

Sorry to hear you had an emergency; hope all is well now.

Taste your must, if it doesn't taste moldy, then I don't believe you're in trouble. Worst you might get is a slight off-taste from the residual mold spore action. Hopefully you removed enough around the visible mold to also get the majority of the invisible stuff, too. We never want mold on our grapes, but it's usually not a death sentence. Some very good wines have been made from slightly mold-affected grapes.

Best thing I know of to do now is to get the fermentation going strongly and done with as quickly as practical, then filter out remaining mold spores prior to ML fermentation. You'll give up some fruitiness and complexity in your wine; a compromise for sure. We're not talking about making $30+ a bottle artisan wines are we ?

Vinquiry, a commercial wine lab and wine supplies company in Sonoma County. Califonia, recommends...

Get your fermenation started pronto. You lost some valuable time by not adding pectic enzyme and lysozyme when you added the SO2. Steps 3, 4 and 5 of my list, below, usually are done during cold soak for a miminum of 24 hours, prior to yeast inoculation. I'm not sure waiting an additional 24 hours is best choice in this situation.

Good Luck, Gene

Some of the background behind the Vinquiry/Lallemand recommendations, plus a couple of my own tips that I learned from my mentors:

1) Add potassium metabisulfite to 50ppm for cold soak period (protection is key here, it will make it a little harder for the yeast to get going when you inoculate, but that is a worthwhile trade-off in this situation) 2) Cold soak white wine must with activated carbon for 24-72 hours to absorb as much moldy flavor as possible (great for whites, but not good on reds because it also absorbs a lot of color). Rack white juice off the settled lees, leaving the majority of the activated carbon and most of the remaining mold spores in the settled lees. Later rackings and filtration of the wine will clear up the rest of the activated charcoal haze. 3) Add powdered grape tannin (creates a more hostile environment for the mold) [note: great for reds, but only use on whites if you like tannic whites]. This is not going to be a long-cellared wine if any mold spores survive into the bottle, so don't overdo it on the tannins, lol. 4) Add pectic enzyme to the must to get quickest grape maceration (making the job easier for the yeast to get to the fermentable sugars). You want to get your primary fermentation done quickly in this situation. 5) Add lysozyme to the must to kill off bacteria in the must (bacterial infections often accompany the mold, nature doing what it knows best when it comes to decomposing). 6) [My own tip here:] Go a little heavier (maybe 1.5x) on Fermaid K or other yeast nutrient (just before yeast inoculation) to keep the yeast happy during the yeast population growth phase. Also, heating the must to 65-70F during this nutrient addition will get your fermentaion going quicker, at the expense of fruitiness of the wine, always a trade-off.) 7) Double the yeast inoculation amount, to minimize the lag phase (you've inhibited the yeast growth somewhat by adding the potassium metabisulfite in step 1, above. This compensates for the inhibition. 8) [My own tip here:] For reds, if the fermenting must hasn't reached 85F by day 4, apply moderate heat over a period of about one day to get it there on day 5. [5 deg F per day is safe, more than 10 deg F per day is asking for trouble... You don't want to heat too rapidly, because the thermal shock can make your yeast unhappy, and unhappy yeast fart H2S, ewwww.... Yeast are happiest when the temperature is steady, +/- 2 deg F per day swings, but we gotta compromise a little here to get the primary fermentation over quickly.] 9) Do light mid-ferment yeast nutrient additions during primary fermentation (keep the yeast happy during the anaerobic, alcohol-producing second stage). 10) Press off red wine from skins early (9 deg Brix is earliest I would personally do it) to minimize contact time of the fermenting must with the mold cells). 11) Keep the free run separate at press-off time (of reds) because the free run will have less moldy taste [so at least a few bottles can be primo :-) ]. 12) Filter out any remaining mold spores prior to ML fermentation - filter your free run first.... don't re-expose it to mold spores from the pressed fraction. You can't protect the wine with SO2 during ML fermentation because the SO2 will inhibit MLF, so it is important to get rid of the spores prior to MLF. 13) dose with S02 to 40ppm after ML fermentation to minimize further spoilage (versus 25-30 ppm S02 in typical fermentation protocol).

snipped-for-privacy@hotmail.com wrote:

I got my ferment going fairly quickly and the fermentation smells pretty normal. I don't think the mold got very far into the must, just surficial. Any thing I should watch for? If it is in the wine, will it be clearly evident by taste? So far all looks fine.

Dan

gene wrote:

Sounds like you caught it soon enough. Just taste it after it is fermented. Let your taste buds be your guide.

To put things in perspective.... molds are fungus, mushrooms are fungus and the wine yeast is fungus, too (saccharomyces means sugar eating fungus).

The kind of mold you had growing on the thawing must could have been 'noble rot' botrytis, the kind that makes for good late harvest wines. Or it could have been a penicillin mold. If so, it won't hurt you, but would give a bitterness to the wine. Or it could have been Brettanomyces mold, in which case it would give the wine a musty/earthy flavor. Other types of mold can leave fishy or 'gym socks' flavors.

A small amount of off-taste mold spores can remain in the wine without perceptibly affecting the flavor of the wine. But remember, any residual sugar in the wine is food for mold to grow. And mold can continue to grow in any wine that is in contact with wood; it feeds on the wood. If the wine is kept in glass/plastic carboys or stainless steel containers, your risk of the mold growing is low. But the mold can grow on the cork in the wine bottle.

Commercial wineries filter any mold-risk wines right after fermenting, to stop the growth by removing the spores. If the mold spores get growing in an oak barrel, that barrel is probably permanently infected.

If there is a detectable moldy flavor, the only way to deal with it is to scrap the batch or dilute the heck out of it in a larger batch of wine.

Gene

snipped-for-privacy@hotmail.com wrote:

You are beyone the point of concern. That does not mean that you are guaranteed that it was not damaged. Just that there is nothing to be done or way of detecting a problem untill it is finished. Worry at this point would be meaningless and just feed your ulcer. I would just go allong as normal, with out worry, but keep a note that there might be a problem and see if you can taste anything unusual at the end. If you do, condcider it a learning experience.

Ray