I guess 'Morphology' is as good a place as any for this.

I've had my ginger beer production line on the go moreorless continuously for nearly a year now. It's a simple process - 500g 'raw' cane sugar dissolved in a warmed pan of water, plus 50g of well-steeped sliced root ginger and juice of two lemons, both strained, and left to cool. Bottle 5L of the last fermented batch from a tapped glass demijohn, then add the cooled fresh wort to the dregs, add water to fill and leave to ferment for 5 days or so. Now and then, a good wash through and restart with fresh yeast (Lalvin EC-1118 Saccharomyces cerevisiae ex bayanus - a commercial champagne yeast).

After a couple of previously discussed teething issues associated with undesirable additives in the sugar, no real issues. A mildly alcoloholic thirstquencher to see me off to the land of Nod each night.

Then instead of the usual mucky froth on top of last week's batch, I got a smooth, gelatinous mat that I presumed to be a possible SCOBY, which I binned. Today's batch ;; same thing, but this time I've taken samples for experimentation (leaving a good part in the demijohn with the new fermentation batch).

AFAIK a traditional Ginger Beer Plant contains S. florentinus and Lactobacillus hilgardii plus (possibly) an acetic acid bacterium (AAB) which I'd really prefer not to have. Though I have spotted the odd suspicious looking tiny midge fluttering around the demijohn.

Not actually noticed any significant change in taste yet, so I'm quite puzzled as to what exactly is going on.

Edited Tuesday at 09:16 PM4 days by sethoflagos
erroneous declension

It seems it might be aerobic acetobacter spp. 'Aerobic' is the clue to the solution.

1 hour ago, StringJunky said:

It seems it might be aerobic acetobacter spp. 'Aerobic' is the clue to the solution.

I'm not yet getting the vinegar though, at least not noticeably. On reading up on AABs, I notice that the anaerobic Zymomonas mobilis is another possibility. As this is an important feature of palm wine fermentation hereabouts, it ticks a couple of boxes (ambient temperature, local endemicity etc.) in addition to the lack of vinegariness (if that's a word). Just opened tonight's bottle and did a sniff test for H₂S. Not obvious, but a long apprenticeship in the paper industry nuked a lot of my sensitivity to that one.

Edited Wednesday at 12:19 AM4 days by sethoflagos
duplication

42 minutes ago, sethoflagos said:

I'm not yet getting the vinegar though, at least not noticeably. On reading up on AABs, I notice that the anaerobic Zymomonas mobilis is another possibility. As this is an important feature of palm wine fermentation hereabouts, it ticks a couple of boxes (ambient temperature, local endemicity etc.) in addition to the lack of vinegariness (if that's a word). Just opened tonight's bottle and did a sniff test for H₂S. Not obvious, but a long apprenticeship in the paper industry nuked a lot of my sensitivity to that one.

Are you sure it's anaerobic in the space above the must?

Hadn't known ginger beers used a SCOBY - a stunted knowledge due to commercial GBs here not really brewing anymore. So this is more like a kombucha, (the SCOBY I'm familiar with)? We also buy vinegar with "the mother" still in it - it's just little bits gathered at the bottom, not a pellicle. I had wondered if that mother could be used in kombucha brewing, but learned it was a little different in culture and insufficient in something (yeast?).

If there's a nose numbing, you can sensitively test for H2S with lead acetate paper. Just hang it in the headspace. You can buy it almost anywhere (because people also buy it to test their water supply) fairly cheap. I had to test some well water some years ago and was able to just drive to a hobby store and buy some strips. Not saying it's that simple in Abuja (?) but seems possible if there are many people in the area on private water systems. (Also: please do not get kidnapped! New Yorker had an alarming article about massive kidnapping around your neck of the woods.)

25 minutes ago, StringJunky said:

Are you sure it's anaerobic in the space above the must?

Not absolutely oxygen free, but it's well-flushed with a lot of CO₂, and, at risk of repeating myself, I'm not drinking 5% vinegar 🙂

4 minutes ago, TheVat said:

you can sensitively test for H2S with lead acetate paper.

Yes, my inorganic chemistry is reasonably okay.

7 minutes ago, TheVat said:

(Also: please do not get kidnapped! New Yorker had an alarming article about massive kidnapping around your neck of the woods.)

Fake news. I've only been held hostage once and that was back in 2002.

Is the stuff only on the surface (like a pellicle), are there gelatinuous blobs throughout and/or does the rest of the liquid seem more viscous? Surface is smooth?

7 hours ago, CharonY said:

Is the stuff only on the surface (like a pellicle), are there gelatinuous blobs throughout and/or does the rest of the liquid seem more viscous? Surface is smooth?

Yes, it's a translucent white surface pellicle a uniform couple of millimetres thick with a smooth, silicone-like texture. Quite tough - it takes some effort to tear. The rest of the brew is 'normal' and homogenous.

Actually thought about @StringJunky 's 'mother of vinegar' proposal overnight. If the rate of conversion to acetic acid was slowish, then the 10-14 day process needn't get anywhere near completion to still fit his idea. May work in a 'slightly aerobic environment too. But then the beast is rather on the bulky side.

That really sounds like a pellicle then. If you ferment for 2 weeks do you get something like 5-6% (v/v) of alcohol? Concurrent acetic acid fermentation will carve out a percentage depending on oxygen availability but with CO2 in headspace it can be very low. But I would have expected a fairly thin pellicle layer at most.

Wild yeast also forms pellicles alone, but due to the lack of cellulose, they tend to tear easier and are not really rubbery. There are members of the Acetobacteraceae that are able to produce cellulose even under microaerobic conditions. IIRC Gluconacetobacter would fall under this category.

Yesterday's batch isn't noticeably bubbling after 24 hours, though a thin pellicle has begun to form so something is amiss. I've added a fresh bit of yeast to try and get it going, though I'm betting I'll likely have to do a full sterile reset. See how it goes.

I haven't been getting full stoichiometric alcohol converion, I think. Maybe 3'5% or so, but that's a guess. Should really get myself a hydrometer sometime. I like quite a tart drink anyway, and put the acidity down to a bit of lactic fermentation (which I've actively encouraged). As I said earlier, I've seen something suspiciously vinegar fly-ish loitering around so perhaps it's no surprise if one or two found a way in.

I've been zonked out a bit the last few weeks with a couple of malaria attacks, so I've put off bottling when I've not felt up to it. I'm thinking that leaving the brew in the demijohn when the fermentation rate has dropped off probably negates my CO₂ flush protection argument. Works only at a particular level of laziness perhaps.

If anyone wants to try a brew or other edible with gut comfort in mind, I've been having some good results from L. rhamnosus. I gather trad ginger beers tend to go with L hilgardii, but it looks like some other L. species will also serve as well.

I was returning wheat to my diet a while back and trying to smooth the transition with some of the probiotics in non-dairy yoghurts which can help with grain digestion, especially those pesky gliadins. Tinkering with various blends, I tried adding some supplement rhamnosus at room temperature and giving it a day or two. Gut settled down rapidly after that. (A pitfall of trying no wheat for a while is enzymatic downregulation - basically, the gut colony scales back on the species that were handling wheat. So when you restart, the species remnants have to start reproducing quickly and that means gas. So if you can nutritionally inject some of those species in there, like L plantarum, L casei, B infantis, B breve, L rhamnosus, et al, it can help.) I had been eating some yoghurt brands that had some of those in the mix, but rhamnosus seemed to really hasten the flip back to normal. CAVEATS: This is anecdotal, so far as my experience goes, and gut biomes vary quite a bit, so I want to look into research some more on specific strains. Am also going to try L reuteri, another candidate. (Sorry, a little off the ginger beer rails.)