Referment in bottle?

If you did have a referment, what was it caused by?

I know it is a sensitive subject, but I’m just curious if anyone has seen it, encountered it, or had it happen to them personally? How big of a concern is air contamination? Had about 10% of a homebrew batch go south. Very sporadic, super frustrating! I did a biofilm removal step, as well as a thorough sanitation, and the wine went through a .45 absolute millipore filter. There is about 7.1g/L RS in the wine, FYI. The wine that started to referment isn’t bad, just not a still wine like I had intended to make it.

I’ve bottled very few sweet wines, but in 1996 we were making a Muscat. I don’t remember the RS, but it was sweet. It went through a .65 and a .45 on the bottling line, which bubble tested fine before and after bottling. The glass we used was from the year before, so that was probably the culprit. It was about 2/3 of the wine that continued fermenting in the bottle.

What is a biofilm removal step?

I’ve wondered for years about the potential impact of glass on wine. Winemaking sanitation protocols are followed, the bottling line is sanitized, corks are sanitized and come in sealed bags, but the glass is just packed in unsealed cardboard boxes. I’ve seen really dirty glass, seen a few bugs inside bottles, etc. Even some recently-manufactured glass can be quite dirty on the outside of the bottles - you definitely notice that after handling thousands of bottles over a few hours - so what’s it like on the inside? Sparging the bottles takes out some of that, but likely not all of it. Seems like that must have some effect on the wine and result in bottle variation or spoiled wine in some cases.

How did a can of Pepsi get in front of my post? Strange!

It would be interesting to do some plating tests on what lives inside an empty and supposedly clean/new bottle.

Funny that in home winemaking it’s pretty standard procedure to douche the bottles, when that’s not done with commercial wines. Sanitizer Injector for Red Bottle Tree | MoreWine

Well, that’s a strange concept: sanitize, silver, and then dump $200 juice into a dirty bottle. Why skip such a simple step?

I don’t know if some of the really big bottling lines have an automated sanitizing setup for the glass but I’ve never seen one even on the bigger trailers (~2,000cs/day) I’ve worked on. I’ve used the type of sanitizing procedure shown on the MoreWine page that Wes linked to but it’s obviously too slow for anything but manual or semi-manual bottling. Anyone know of bottlers that have something on their line to sanitize glass?

I’ve seen some of the biggest and fastest bottling lines in the world, and they didn’t wash their bottles ahead of bottling. No one does, that I know of. I did get to see the Budweiser bottling line in Fairfield, and after bottling or canning, they heat the finished product up to 160F. Maybe we should do that with wine? Just kidding. By the way, I asked if they did that with kegs too, and they said no.

Drew, it’s a matter of how much time it takes to sterilize a bottle. You could do it with chemicals or with heat, but either way, there’s no way to guarantee sterilization, have all the water rinsed out or have the bottle be cooled back to cellar temp in a quick enough manner to keep up with a bottling line. And you can’t do all the glass ahead of time and keep the bottles sterile, hours or days ahead of bottling.

OP, it hasn’t happened to me though I only make dry wines. “Air contamination” shouldn’t be a factor unless you’ve got some really dirty environment. If the remaining 90% of the bottles truly are stable (I’d keep a close eye on them to prevent bottle bombs), then I would look towards how that 10% was handled differently. Did this wine get a dose of sulfur prior to bottling?

ive never seen glass washed. We check the manufactured dates on received glass and red tag all older than 2 years and run filter tests on them.

In terms of referment - I’d never think it would come from dirty glass. Filtration - even sterile filtration - doesn’t remove everything (but it does make you feel better).

It sounds like you did just one pass through a .45… That makes me think you might have blown the filters at some point.

Or… Maybe you had a cool case of zygo?

+1 to those suspicious of bottle sanitation.

A friend once bottled Chardonnay into glass procured from a prominent industry supplier. The wine was ML-complete and crossflow filtered before bottling, then passed .45 micron at the line. A random number of bottles came out with the aroma and taste of soap.

All possible culprits ahead of glass (including sanitation of lines/ equipment and warmth during aging) were eliminated – exceedingly unlikely the soapy taint was wine-borne.

Most plausible vector was soap in the glass, which was brand new. Scary.

There have been quite a few re-ferments of wine with RS from up there, mostly the Alsace Varietals. I think air and or bottle contamination is the most likely culprit.

I screen print all my PN glass. That process is done just a couple weeks prior to bottling. I do like the idea of the bottle getting very hot to apply the printing in regards to sterilization. They also reject any off bottles and a few with air bobbles break as well. Overall very happy with the decision to screen print on many levels.

I was interested in that company that was going to recycle glass by washing it. I told them I would be interested once they were up and running for 2-3 years. The machine they bought did not work right and they folded pretty quick. They sued the manufacturer who I think was out of Italy but I never saw the results hit any of the wine press. I still like the idea of buying recycled glass then having it screen printed. Maybe someone else will figure it out one of these days.

I’ve recently had a couple reports of viognier fermenting in bottle – malo, I suspect. I had stopped MLF before it finished and knew there was some risk. I thought I could get away with bottling at pretty high SO2 level, but this was a hand bottled effort, and I suspect the failures are ones that picked up a little extra O2, which dropped the SO2 and allowed MLF to restart.

That’s a tough call, Stewart. I’ve talked with more than one winemaker who has bottled wines without filtering that were not done with ML and who said they’d never had a report of problems (at least at the time when I spoke with them). I think with low enough pH you might be able to get away with it. I bottled a non-commercial Gang of Six 2009 Nebbiolo that had not quite finished ML and have not had an issue with any of those bottles - pH was around 3.25 IIRC.

Stewart, there’s a great quote from a winemaker, I think his name was Murphy: If your wine won’t finish ML and you’ve tried everything else to get it to go, just bottle it, and it will finish ML.