Wild/Feral fermentation questions

I have some questions for those who do not (purposely) innoculate their must. Hopefully a few people could weigh in on:

  1. Do you still put a little bit of so2 on the grapes even if you are doing a wild ferment? I’d like to have the complexity of many yeast strains. Will a dose of so2 kill off all but S. cerevisiae?
  2. Wat is the risk I would get spoilage micro ogranisms if I wait until after primary to put so2 in? Is it a light risk or a heavy risk?
  3. If Im using whole cluster or whole berry whats the best way to get so2 on it if I do use it at the beginning?

Thanks in advance if anyone can answer.

SO2 at the crusher: this can range from no sulfur to 100ppm (I’ve never heard of anyone using more than that, tho I suppose you could). Most yeast are fairly sulfur tolerant, so adding some at the crusher won’t kill your native ferment possibilities. Thierry Allemand use to add no sulfur at the crusher…he lost a lot or two some years back, so it’s my understanding that he now adds 5-10ppm (a very small amt of sulfur…I use the same approach when the fruit is all clean…I use a ‘typical’ amt of sulfur in barrel after ML and prior to bottling tho). I’ve talked to Michael Dashe, a big native ferment proponent, and it’s my recollection that he uses more sulfur at the crusher and doesn’t have any problems getting a native ferment going

Killing everything but S. cerevisiae: Not possible. For one thing, Kloeckera is quite sulfur tolerant. Also, one of the benefits of native ferments is getting beneficial non-S. cerevisiae (I assume that part of your question was to understand the degree/effect of sulfur…not a desire to have an S. cerevisiae only, but thought I’d point this out anyway).

Spoilage risk: the biggest risk is the Kloeckera that will almost certainly dominate the beginning of your native ferment. Kloeckera dies at ~2-3% alc but until then it produces a fair amount of ethyl acetate. As long as you can get your ferment temp up to at least 80 degrees (75 degrees might be ok too), this isn’t a problem as EA is volatile, and the hot ferment will blow it off. But getting a small ferment up this these temps can be hard/impossible. A half ton of grapes in a T bin (double wall, so is insulated) is no problem…but a half ton in a macro bin (single wall and much shallower than a T bin) is a bit dicey. This is a real problem with fermenting 5-10 gallons as you’re thinking about. You’d have to get up to 2-3% alc without EA somehow. An exotic/creative/expensive approach is to start the ferment with encapsulated yeast…i.e. yeast encapsulated in beads in a mesh bag that you can remove at the desired point (these are intended for dessert wines, but could be used for your purpose…of course there’s no guarantee that you won’t introduce a few cultivated yeast this way). Or you could ferment a small portion of your batch with an alc intolerant cultivated yeast (putting the remainder of your batch in the fridge)…when the initial batch is done fermenting, you add it to the remainder to get it up to 3% alc (you’d have to have some way of convincing yourself that you’ve killed the cultivated yeast…alc is the easiest way…even so, there’s no guarantees you’ll get them all…but that’s always true with native ferments). An alternative is to use a Chr Hansen yeast, which have non-S. cerevisiae to simulate native ferments…I don’t know of anyone that sells these in smaller amounts tho (i.e. less than 500grams).

Another risk is the various lactobacillus bacteria (lab)…these produce VA, and a high VA can prevent yeast from fermenting. There are other factors that cause stuck ferments, but lab is the main one (high brix and insufficient nutrients being the others). Controlling lab is the main reason to use higher levels of sulfur at the crusher. The level of risk here is directly related to how clean the fruit is, and how clean everything the fruit touches is (including preventing fruit flies, which are basically a bad organism transport mechanism).

Whole cluster: wash your feet and stomp on the clusters to get some juice in there…you want the grapes/clusters entirely covered in juice, or the risk of VA producing organisms (and/or mold) growing on the surface is very high. Anyways, once you have some juice, add the sulfur and mix.

Whole berry: Not a problem with Pinot…pinot has such thin skins that 100% whole berry will still give you a lot of juice…so just add the sulfur and mix.

There. I’ve used 20 minutes productively and didn’t worry about the rain once…I’m so proud of myself!

I do all wild ferments and add from 0-10ppm So2 based on expected gallons of finished wine which for our basket press is about 145 gal/ton. If the fruit is uber clean it gets none, if we find any bad clusters it gets 10ppm.
There are always spoilage risks. Make sure you have enough juice to cover the berries/clusters so you don’t have oxygen pockets in the fermentor. Keep the cap moist and do regular punch down intervals for your desired level of extraction. We do mostly t-bin ferments but some times have small amounts that we do in food grade trash cans. The small ferments tend to get going and finish earlier but much smaller than 15 gal of must you may have trouble getting them warm enough. If your not going to cold soak under co2 get the fermentor above 70 to get a quick starting ferment.
If you don’t so2 from the start you can always add it prior to a punch down and mix it all in.
If you are very interested in what you have in your juice you can always get a scorpion (http://www.etslabs.com/analysis.aspx?id=$JWSP) done to see what is actually in there. We do that at the juice stage, after pressing, and prior to blending. Might me more than you want to spend at $140 but if you really want to know is a great way to find out whats there. Best of luck to ya.

At this point all of our reds go native. I use anywhere from 30-60ppm KMS at the crusher, with the occasional lot getting nothing. It’s just a cases by case basis.

Berry, you’ve gotten some good input already, but more FWIW.

I do native ferments on all my reds. I typically add 30-50ppm SO2 at the crusher and have never had a problem with native fermentation starting. I know of producer who add no SO2 at the crusher if the fruit is clean, but I’ve never gotten up the guts. You wouldn’t add SO2 until after secondary fermentation (ML), so either hit it at the crusher or let it ride until alcoholic fermentation and ML are done, then hit it.

I forgot to mention earlier (and kept meaning to post my results, but never did) that SO2 in bin or tank (free) doesn’t last very long anyway. In tank, the longest I have ever found any free was about 24 hours after add at the crusher. It is only for an initial kill, but goes away quickly. In bin I have found some free lasting a few days, but again, it doesn’t stick around for more than 3-4 days.

Thanks for the detialed response Eric. very informative.

All this is worrisome. One fermenter has 125 pounds of grapes in it and the other one about 200. Im worried it will not be hot enough. I might be losing my nerve here…

There is only juice at the very bottom. It is mostly whole berries right now.

With clean fruit is it a minor risk or a significant risk? Since this is for fun I can take chances but I wonder what the odds are of something going wrong.

Right now it is mostly whole berries with juice way at the bottom. I was going to try a semi-carbonic approach at the begining to try and get floral aromatics and a light extraction but reading what you guys are writing is making me think I should crush a bit to get some more juice.

Thanks for help!

Thank you.

Part of my challange is I am not sure how to calculate PPM when I have whole berries. Im not sure what the must to whole berry “volume” is. Ive found some stuff on the web that says use a half teaspoon of sulfite crystals for every 100 pounds of grapes. Since weight is the measurement Im sure of Im thinking of going that route.

Interesting to say the least. Can so2 that is bound end up being free later or is it that once it is bound it will always be bound?

FWIW berry, last year i had about 300lbs in a stainless 55gal tank. I wrapped the tank in an electric blanket and the temp peaked at 86 for a couple of days. I also put the tank in the sun when I could

Two years ago, I had about 100lbs in three plastic fermentors and could only get peak temps into the mid 70’s. So far the wine is the shits More grapes all in stainless made the difference

I actually have 250lbs of Pinot that was picked late yesterday. Long story short I wasn’t ready (thought pick was going to be today) and had no dry ice. Native yeasts have already started fermentation.

Was that 250 LBS crushed Tim?

I wonder if mine will take longer because this is the first time Ive made wine here and thus no feral yeast.

No, that was the lbs of fruit into the fermentor. This is my first year of three that I am letting it start and hopefully ferment on it’s own. First two years I used RC212 and D254 in the garage.

I think my fermentation started so fast because the grapes were picked mid day and it took me a few hours to transport. As I was trying to sort, a few patches felt warm. This was after adding about 55ppm of sulfur (there was some rot on a few bunches).

I meant are you crushing the fruit or doing whole-berry or whole-cluster?

Also, how much if any so2 did you add?

One vineyard Im using had zero rot. The one had very very little botritus on maybe 10 out of hundreds of clusters. I just dropped those when harvesting.

I just stuck my head in the fermenter and I think I may just barely smell some alchohol. But it may be my imagination.

I mixed in a 1/2 teaspoon of potassium metabisulfite into the fermenter and agitated it enough so that the juice is now up at the level of the top of the must.

Since this is just a fun project I was tempted to leave out the so2 at this point but I thought I may have possibly smelled the fainted whiff of acetic acid so I blinked and added the sulfite.

With clean fruit and a watchful eye the risk is very minimal. In 10 vintages of winemakeing I have not had one single stuck or otherwise off fermentation. In my opinion you really have to have bad fruit and/or really neglect the wine to scew it up.

You will still get plenty of carbonic character with whole berries. More juice in the beginning if you are not blanketing with co2 will help keep lots of sutff at bay. I have used co2 pellets to keep things gassed. I just dont let it touch the friut. Either put it in a metal colander on top of the cap or suspend some over the side with cheese cloth. I have also made a sugar water mix in a carboy and started the ferment the day or so before we got the fruit and used the expelling co2 to blanket the ferment via tubing.

Not in my experience. Foursight has never had any commercial yeast on site (our Sb and rose are made off site) and was a brand new winery and we had no issues the first or any other vintage. Those buggers seem to be everywhere.

I crushed most of it. Bought a zambelli crusher/destemmer this year and couldn’t figure out how to change the spacing on the rollers. I wanted to do about 20-50% whole cluster, but the bunches were falling apart as I was sorting, so it came down to throwing in what whole clusters I could find (and the ones I did were small)

I added about 9grams of S02, which should get me to about 50ppm or so based on fermcalc. I found quite a few clusters with some rot, so I wanted to add that level to protect.

Does anyone have any insight into how long you give the native yeasts before you decide to inoculate? I’m worried the fermentation won’t get to the peak temps needed. Two days in and I am still hovering at 71 degrees.

We do not inoculate and have no problem finishing, but it’s been years since I’ve fermented on that small of a scale. Our ferments rarely get above the 70’s, so I think it would be more useful to track brix rather than temp at your size. If you are getting close to the end and your temp drops, I would try to warm it up somehow.

Visqueen & a space heater – you’ll get plenty warm.