Kefir "beer"? How high, how low can you go?

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bernardsmith

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Not sure if this is best place to post this question but here goes. Sunday evening (5/5/19) I added a couple of tablespoons of kefir grains (that I had dried and had stored in a fridge for a few weeks because they were in excess of the amount of grains I need to make kefir from milk) to 12 oz of molasses (not backstrap) to which I had added enough spring water in which I had boiled Galena hops for about 20 minutes to bring the gravity of the molasses to about 1.050. After a couple of days I have significant krausen and the airlock is bubbling away - not vigorously but clearly pushing out CO2. (not certain if it took two days for the fermentation to take off because of the relatively small size of the yeast colonies involved or because the grains had to re-acclimatize first to a liquid environment after having been dried for storage and then acclimatize to a lactose-free environment for the very first time).

My idea is to try to develop a culture that prefers sucrose to lactose but which still contains a diverse population of different yeast and perhaps bacteria that self select in the presence of hops which I can then use to ferment honey (mead) or malt (beer) . Has anyone tried to brew a molasses "beer" using kefir grains? How dry were you able to ferment the sugars? Milk contains about 20 points of lactose but it is, I think, the bacteria that dominate in making kefir. The lactose becomes lactic acid although perhaps the kefir might hit 0.5 - 1% ABV.

I intend to measure the SG this evening and to taste this "beer" although for this batch I am not looking for a great tasting drink as much as I am trying to encourage a colony of diverse strains of yeast that may or not still be a scoby but which will produce a complex range of flavors. Thoughts? Thanks
 
Hops greatly inhibit the bacteria (bacteriostatic against gram positive bacteria, specifically). Your molasses fermentation probably just has yeast activity.

Molasses is high in minerals (e.g. iron), which lend a rather unpleasant metallic taste when fermented, in my experience, and from what I've read from others. YMMV.

Yeast raised in sucrose/dextrose/fructose generally don't ferment wort very well, so you'd want to make a wort starter if you plan to make beer from barley.
 
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By taste , this evening, I would agree that the bacteria (lacto) have been inhibited and the yeast seem to be what's cooking. Gravity has dropped almost 10 points since Sunday evening - not a huge amount, I know, but a) Sacch yeast don't dominate the kefir scoby and b) as I wrote, I had dried and chilled the kefir for several weeks before resuscitating them on Sunday (I had also dried and chilled my active batch for a couple of weeks and it took them about 3 or 4 batches of milk to get the ful spring in their step again).

The molasses at this stage tastes OK - not metallic. I wonder if the metallic flavor comes from the lowest molasses on the ladder - the waste of the waste , as it were: black strap?

Your point about an anticipated problem using this yeast to ferment malt is noted. I also make mead - and I wonder if the yeast might be happier fermenting honey...
 
I wonder if the metallic flavor comes from ... black strap?
That could be the case. If your thing doesn't taste metallic after it ferments dry I guess you'll have the answer.

Partially refined cane sugar like turbinado seems to be ok
 
The molasses are still bubbling away and after 7 days have dropped about 30 gravity points. I removed the grains (because I was nervous that the ethanol would kill them but there seems to be something going on (and it's possible that I missed some tiny grains) because even with the grains removed the molasses still seems to be producing CO2. Intend to measure the gravity gain this evening but this is quite drinkable.
On another note , I made up some lemonade (lemon juice, water and sugar) and added the grains I removed from the molasses to the lemonade. For about two days or so no apparent activity but I checked this a few minutes ago and I see that while the airlock is not bubbling there is clear evidence that some gas is being produced given the differential in the height of the water in the bubbler
 
I looked at the molasses I used that tastes metallic; it's not blackstrap.

For this "experiment" I am less interested in the taste and more focused on whether I could move milk kefir away from milk sugars to sucrose (the main sugar in molasses) and if so whether I could get the grains to thrive while fermenting to a level akin to a session beer. and I seem to be close to achieving this.
 
This is really fascinating - Certainly agree that the flavor of this um... brew.. is an acquired taste. Not so much metallic as mineral-y, but days after I removed the kefir this is still fermenting. Bottled it this morning and I have had to open the flip tops to release some of the CO2. I would have bet the farm on the fact that the milk kefir grains would have quit long before now but I wonder if the molasses provide the kefir with critical minerals that this organism requires? But insofar as I removed all the grains from the molasses some of the yeast must have uncoupled itself from the kefir and is still busy fermenting away.
Update on the lemonade to which I added the grains after removing them from the "molasses beer" - this fermented dry and was quite delicious. I have now added the grains to some sugar water and have been watching them rise and fall presumably as they produce CO2. So the acidity of the lemon juice did not kill these critters.
 
Measured the molasses "beer" and using only kefir grains I was able to reduce the SG from just over 1.050 to 1.016. I have to burp the flip tops I bottled it in because of the amount of CO2 that is still being pumped out. I guess, bottom line, I am totally surprised at how alcohol tolerant it is possible to culture the grains - Thirty -four points is about 4.5% ABV, though some of this drop may be bacterial reaction on the sugars to produce acids rather than ethanol. The pH is 4.17
 
Acid production doesn't drop the gravity.
Lactic acid is about as dense as the sugar.

So actually the reverse is true... Acid in sour beers tends to increase FG maybe 3-4 points. But at that pH you didn't have significant acid production. Hops are stifling.

Cool that it fermented. Hope it works well for whatever you're planning. :)
 
I forgot I added the hops and I did that specifically to inhibit bacteria in the kefir and encourage the yeasts. I have no specific plans except to see if I can fish for some K-marxianus yeast from some substrate and so be able to ferment lactose. Located a couple of papers that suggest apple juice can contain that strain of yeast and apparently kefir grains are attractive to K-marxianus and can pull it from raw milk as the kefir is cycled repeatedly through batches of the milk.
 
I have no specific plans except to see if I can fish for some K-marxianus yeast from some substrate and so be able to ferment lactose. Located a couple of papers that suggest apple juice can contain that strain of yeast and apparently kefir grains are attractive to K-marxianus and can pull it from raw milk as the kefir is cycled repeatedly through batches of the milk.
I did see your thread on MTF.

My understanding is that Kluyveromyces ubiquitous, so yes, you can find it on apples but also pretty much any other plant or even floating around in the air. The difficulty is isolating it since lots of other yeast genera also inhabit apples and every other wild habitat.

In my opinion (and I've never done this or heard of anyone doing this), if you want to ferment milk I think your best bet is to make a starter from lactose with yeast nutrient and then add a bunch of wild cultures in.
If something drops the gravity voilà -- you have yeast that ferment lactose.
 
RPh_Guy, You have just given me an idea: Just thinking to myself and letting you listen in.
I possess kefir grains. I use these grains to "culture" milk for my cheese making. To prevent the whey from continuing to sour (in cheese making you might "back slop" with kefir (the "soured milk", not the grains themselves ) for 40 minutes or so of ripening and then the milk continues to ripen another 40 - 60 minutes as the rennet coagulates the milk to form a clean break) you need to kill the now resident bacteria (and yeast) so for whey wines and meads I typically heat the whey to about 180 F and allow it to cool.
Now, kefir grains contain (I think) some K-marxianus but the kefir grains don't produce more than about 1% ABV from the lactose. I am not sure whether that is because of how this scoby works - so, for example, producing more alcohol might kill some of the bacteria which then might create problems for the polysaccharide net the yeast inhabit; or because the lactose fermenting yeast is, in symbiosis, cooperating rather than competing with other bacteria and other yeast that eat the remaining sugars but produce acids, not ethanol; or because there are only 20 points of gravity in the whey (so a potential of about 2.5% ABV) AND typically kefir is added to milk - not whey - and is added for 24-48 hours and not a week or longer... So I wonder if it might be possible to take some kefir grains and add those to whey to see if they produce CO2 and ethanol over say, 7-10 days... That's the plan. I intend to make a batch of cheese tonight that should leave me with about 7 pints of whey and I have enough grains to transfer some to the whey (say, 2 pints) to see what happens over the course of a week.
 
My understanding is that milk kefir grains need to be returned to milk regularly (specifics unknown) in order to survive. I've been using "water kefir" grains, which are used to fermenting regular sugary water, to ferment standard beer wort and reached as high as 7.7% ABV. Similar to your experience, the beer is not sour since the hops seem to inhibit the bacteria, and it's mostly the various yeasts which are active.
 
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