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Thread: Top scum

  1. #1
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    Question Top scum

    It seems that on a couple of carboys, a scum layer has developed. Not really mold, but just a layer of "whitish" scum of Yeast(?) or some other stuff.

    On some of the bottles it appears to have none, and on others its a good bit.

    Is this just stuff that you slowly eliminate by racking? Is it an indication of contamination? I have used all new equipment up til this point, and all was wash cleaned as called for.

    Is there something in the process that could be improved or lessen this in the future? Or is this just normal and seen from time to time? Are some yeast more prone to this happening?

    Thank you.

  2. #2
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    Typically that's a classic bacterial contamination sign. Though some yeast strains can form a pellicle, a stalactite-like formation of yeast colonies. Really that's only the flor sherry strains, not often used for meadmaking since they're aerobic fermenters. Best suited to sherries and estufa-treated, oxidized ports and the like.

    Typically the best way to troubleshoot contamination is to do a literal and exacting task analysis of the process. Like "OK, then I set the spoon down. Where? Was that clean? OK. Then I pour it into the funnel in the carboy... wait, where did I set the funnel after I sanitized it?" kind of thing. When I was new at all this, EVERY bleeding thing I did, before it touched the mead/beer/wine/soda whatever, I triple-thought: "is what I'm about to do going to bring anything into contact that may not be sanitary?" I look at everything in my hand and say did I sanitize that and what has it touched since then? Did I pet the ^%@ dog again?

    You know it's funny, these things (trying to pin down contamination) can drive you to distraction. At least if you're a slightly anal-retentive biology-geek child of a public health nurse and neurosurgeon who sees germs attacking his mead at every turn . But seriously, do a mental walk-through, a serious, detail-oriented one, before you begin autoclaving the family cat. Usually it turns out to be something simple like a mouth-started siphon, a hydrometer sample poured back into the batch when you forgot to sanitize the sample jar ('cuz you don't pour samples back in), or the like.

    For now, if you're not morally opposed to it, you could consider racking the meads in question out from under the pellicle and sulfiting it to 50 ppm or so (about 1 campden tab per gallon). Many would recommend up to 100 ppm. The thing is that these bacteria will never improve a mead, a very few will cause minor defects, and most will ruin it left unchecked. And the effects increase with time. For sure don't bottle it at any rate; they can often metabolize things yeasts can't and you can get grenades from "finished" meads. Additionally, they can be very persistent in equipment, especially plastic equipment. Most makers of beer styles that deliberately use these "wild" strains of bacteria and/or yeasts (the brettanomyces bruxelensis, brett. lambicus, and the Lactobacilli spp.) for brewing lambics, Gueuzes, and Flemish sour ales, have an entirely separate set of equipment for this type of "biohazard brewing".

    The good news is they won't hurt you; no known human pathogen develops in fermented beverages (that's why virtually every early human culture got into fermenting in the first place, aside from the nutritive benefit and the buzz ). It might have funk a mile wide and not make it past your nose, but it wont kill you.

    Worth asking at this point, what is your sanitation regimen? Each product, from bleach to no-rinse fancy-pants dodecylbenzene sulfonic acid (Star San), has recommended temperatures and contact times.
    Bees, brews and fun
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  3. #3
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    BjornBee,
    I see from previous posts that you have several meads going now. Do the scummy ones have anything in common, well, other than the scum? Is there fruit or other additives in any of them? Are the scummy ones the non-boiled ones? What do you have in your airlocks: water, sanitizer, vodka? After sanitizing your equipment did you rinse with tap water? Did the scummy ones each spend time in the same primary fermenter or get syphoned through the same hose without rinsing between batches?
    George

  4. #4
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    You guys are making me doubt my methods and think my rotten apple mead will never turn good.

    question:
    When making a fruit mead with crushed fruit in a bag, is one camden tablet per gallon enough to sterilize the must?

  5. #5
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    Yup. Techinically it depends on pH and some other things, but generally yes.
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  6. #6
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    Bear in mind that metabisulfites cannot sterilize, and are weak sanitizers. They generate SO2 when exposed to acid solutions. This reduces oxidation and inhibits the growth of bacteria, especially those that depend on oxygen. Sulfites are not good to use for sanitizing equipment unless the equipment is very clean and your solution quite acidic. For questionable apples (the type traditionally used in cider) a good boil is the American way. In my mind, the grind and boil process is what separates cider from apple wine.

  7. #7
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    Thanks Aspera, the difference between sanitizing and sterilizing is important and the terms are often interchangeably used. Sulfites have been the standard must-sanitizer for winemakers for centuries, for better or worse.

    I have to ask, doesn't boiling the must potentially cause hazing (from pectins), darken it, and also drive off much of the more volatile aromas? I just haven't heard much of boiling apple must. I wish I knew more about cider, it's awesome when it's good!
    Bees, brews and fun
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  8. #8
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    Hmmm, whats the difference between sanitizing and sterilizing?

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    Well, I don't know the technical definition, something to do with the fraction of a percent of viable organisms remaining after the procedure. Operating suites are not, contrary to popular belief, sterile: they're sanitary. Now equipment in a finished autoclave is sterile, at least until you open the autoclave. A thoroughly flamed instrument is sterile until it cools a bit and contacts air.

    Basically sterile is an ideal rarely achieved in practice, or when achieved as soon as you use it it is no longer sterile (packaged bandages for example).
    Bees, brews and fun
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  10. #10
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    I thought a picture would reveal more than words. I'll get to some of the questions also. For now, here is two pictures. The first shows some of my better meads, with the two in the back being the one's that have some scummy stuff on top. The second picture shows a close up of the worst one....




  11. #11
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    Hmmmm (sagely stroking beard). That's actually a "maybe" for me; I've seen weirder yeast clumping patterns. Those clots on the top though are a little strange. I certainly wouldn't dump them. Give them a while and see how they do. You could rack and see if those reform. What yeast was that, are they offgassing still, and how old are they?
    Bees, brews and fun
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  12. #12
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    Ben,
    The nasty looking one was started September 23. Good fermentation. Racked two weeks later.

    Starting 1.132
    first rack 1.074

    It did a good bit of fermenting after the first rack, so I'm assuming that it has come down more.

    Was an 18 pound honey sweet mead with white labs - WLP720, made for sweet mead.

    It is still giving off bubbles at a slow rate.

    The picture gives an odd color to the scum. The actual color is very light, almost white, and is similar to the bottom sludge. There is no green or blue, that would normally be associated with mold of some kind.

    This was a heated must, and using all new equipment. All was sanitized with Clorox of some portion my wife made from the book. Not sure off hand though of the mixture. We certainly were going from the book.

    Thank you.

  13. #13
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    I'd bet your yeast just flocced weirdly and it's fine. It's been too long since I've used that one to remember how they looked, but yeast are strange beasties. I've never understood why they always seem to have a ring around the carboy's rings; some odd thing they do to mess with us I guess.
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  14. #14
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    Isn't that too much head space in those pictures?

    I've been filling mine up to the bottom ring of the neck, but I do occasionally get some mead into the tube of the airlock.

  15. #15
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    Quote Originally Posted by MichaelW View Post
    Isn't that too much head space in those pictures?

    I've been filling mine up to the bottom ring of the neck, but I do occasionally get some mead into the tube of the airlock.

    Good question.

    I just went with the basic recipes in the book and the amounts they gave. It was a 5 gallon recipe. I used a 6 gallon plastic fermenter and racked into the 5 gallon carboy. So some of the 5 gallons was lost on the first rack. And I assume that every rack afterwards will lose another half inch or so of volume.

    If this is important in second/third racks, and for long term storage of mead left in the carboys, someone please tell me how to keep the level up. I assume that while some fermentation is still active after the first rack, and so air would not be a big issue. But what about the last rack, when no more fermentation is produced, and I want to leave the mead in the 5 gallon carboys? I have been told that its possible to keep them in carboys for years. Is there more to this than what I'm thinking?

  16. #16
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    Well, how you could do it would be to "sacrifice" one carboy to top off the rest, then put the left overs in something smaller like a 3 gallon carboy, or a few one gallon jugs. I read that somewhere. I wouldn't think a "little something different" would overly affect taste????

    But as to importance, I'll leave that to someone whom has made more than one batch of decent mead.

  17. #17
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    Headspace is only an issue for prolonged storage, where changes in atmospheric pressure cause the airlock to burp air inwards occasionally. Otherwise, on the short term, it's been purged by CO2 offgassing from the mead.

    Folks do the different carboy size thing, have smaller topoff jugs, add a similar finished mead, drop sanitized marbles in to displace (LOTS of marbles, kind of a pain), or don't worry about it. Or keg, my personal favorite.
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  18. #18
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    I had a similar, but not identical, ocurrence with a batch earlier this Spring. I almost poured it out then and there. Instead, I gently stirred the working mead until the white material was submerged (dissippated might be a better word). The yeast flocculated nicely after that and the batch turned into one of the most drinkable young meads I've made. Sometimes, it's a mystery.
    I've found it easier to keep bees than keep relationships. At least when I'm stung by bees I know why.

  19. #19
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    Thats not scum... All of my beers look like that or worse. Not exactly sure what it is, but probably yeast. It could actually be the yeast reacting with O2 in the head space.

    For storage, it would be recommended to seal the container and backfill with CO2. But make sure that it is through fermenting. The glass carboys may not be capable of much inside pressure buildup. Beer bottles are !!

    Now if you want to see what scum looks like, take a dozen whole cucumber and place them covered container of salt brine and let set for 2-3 weeks undisturbed. Now THAT is a scum !!

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