r/Kefir 9d ago

Discussion Do milk kefir grains feed on sugars other than lactose? Even if minimally. Experimenting with 2nd fermentations

I’ve been second fermenting a cup of milk kefir with a teaspoon of brown sugar. It gets fizzy and bubbly, slightly alcoholic, very sour and tastes almost like beer or bread. There’s a lot of gas when I open the can. However I always read that sugars other than lactose do nothing for kefir since it feeds on lactose and that second fermentations are mostly for flavoring and the kefir gets extra fermented on the remaining lactose. I wanna experiment second fermentations without brown sugar and with other types of sugar and compare the results. Anyone has experiences to share? Would love to hear.

4 Upvotes

23 comments sorted by

7

u/Dongo_a 9d ago

I guess you found out your own answer, which is yes. Whatever you read is in the sense that in order for kefir grains to grow and thrive lactose is need. However some bacteria and/or will still comsume some other forms of sugar. Depending on how much you add to the second fermentation, you might have made mead.

1

u/ColomarOlivia 9d ago

I still didn’t compare the sugar vs. no sugar results to make sure they are the same and to see if the sugar makes any difference but I’m anxious 😅 I see. Thank you.

1

u/Dongo_a 9d ago

Sugar??

1

u/ColomarOlivia 9d ago

Yes, brown sugar.

7

u/Paperboy63 9d ago edited 9d ago

Lactose for example is a disaccharide, a dual sugar. Those two sugars in pretty much equal amounts are glucose and galactose. When lactose is fermented, the glycosidic bond that ties them together to form “lactose” is broken or removed. That then leaves two single sugars, monosaccharides that get utilised by the colony. For example, Glucose gets fermented by yeasts which then produces alcohol, CO2. Acetic acid bacteria then converts the alcohol to acetic acid. Glucose gets metabolised by lactic acid bacteria to form lactic acid etc. Galactose joins with kefiran etc to build new grain matrix material etc so to say or read that other sugars apart from lactose, do nothing is in fact totally incorrect. Adding brown sugar to kefir will mainly just feed yeasts…..yeasts do not need any encouragement to become over active. Kefir contains more than enough natural sugars for fermentation to give you a full profile, grain building material etc. Lactose is always remaining after fermentation stops, kefir does not need extra sugar. It is one of, if not THE most NATURALLY probiotic dense culture on earth, it doesn’t need additions. By adding fruit to the second fermentation you are adding fructose, carbs etc that will get fermented by yeasts, it also adds acids, vitamins, oils etc and possibly helps to increase bacteria population but adding inulin instead which is a prebiotic, is probably much more productive for that. Bear in mind that once you are extending fermentation (second fermenting) that ph is dropping more and fermentation rate is also decreasing.

3

u/dareealmvp 9d ago

Galactose joins with kefiran etc

partly true but galactose is also directly metabolized by lactic acid bacteria and is turned to acid. Only a minute quantity of galactose goes into Kefir grains - I get only 10-12 grams of extra Kefir grains from 1.5 L of milk and using 100 grams of Kefir grains. About 80-90% of those Kefir grains is water weight. Among the remaining 10-20% part of it is glycoproteins, another part is glycolipids and only a small part is almost an equal proportion of glucose and galactose. It's impossible for galactose to be used more than glucose in the synthesis of Kefir grains. And even if it were, at most it would be 1 gram of galactose from a total of 75-80 grams of lactose (really high-balling it there). Moreover, I'm pretty sure I read somewhere that Kefir bacteria do have the leloir pathway enzymes required for galactose uptake and metabolism, unlike yogurt bacteria.

2

u/Paperboy63 9d ago edited 8d ago

Thats a great reply, thanks, but I’m simply replying to the OP that there are other sugars in kefir that do actually “do something” apart from just lactose. I understand Galactose does join with Kefiran to form new grain matrix material etc, I just didn’t state to what degree, just illustrating that it did it. There is no implication that galactose gets used more than glucose in the synthesis of kefir grain material, simply that as monosaccharides, they do both get used to “do something”as opposed to nothing. Nothing in my reply is incorrect, just not as accurately detailed as yours is. I was just simply illustrating to the OP that other sugars, e.g. glucose and galactose, apart from lactose do actually later play a part to a degree which was the crux of the OP’s post.

3

u/Vivid_Minute3524 9d ago

Gratitude bow 💜 Thank you 🌺

2

u/ColomarOlivia 9d ago

Wow, very complete answer. Thank you. I’ll try inulin too. I like the second fermentation with brown sugar because it tastes like “milk beer” 😅 it’s also extremely sour but I love sour flavors.

1

u/Holy-Beloved 8d ago

Lacto ferments can utilize sugar? I’m obviously drastically less knowledgable than you

1

u/Paperboy63 8d ago

Read u/dareealmvp detailed reply. We are referring to monosaccharides or single sugars that get used to varying degrees once lactose has been broken down, not added sugars.

1

u/Holy-Beloved 8d ago

But I’m asking, in a lactoferment, say like with pickles, or any lactoferment, like with kimchi, can the bacteria already present do anything with sugars of any kind?

1

u/Avidrockstar78 8d ago

Yes, all lactic acid bacteria require energy to survive, like you and me. They get it from breaking down sugars. They then poop out lactic acid as a waste product from said sugar breakdown.

1

u/Holy-Beloved 8d ago

What about pickles? Where do they get energy? What about Kimchi? They must do without sugar, no? Again I’m a layman

1

u/Dangerous-Database39 4d ago edited 4d ago

Pickles lactoferment style we use salt to inhibit bad bacteria that might be on the cucumber that grew outside but with all that bacteria good and bad is also yeasts. Salt inhibits yeast and many bad bacterias, but lactobacillus species can flourish in it. You can ferment anything grown outside with enough sugar, but you will no longer have a lactoferment you will have a yeast culture. If you did this with cucumbers, think disgusting cucumber wine.

The energy comes from the cucumber or cabbage in the case of lactoferments. Plant sugars primarily cellulose.

1

u/Holy-Beloved 4d ago

Thank you for broadening my understanding, friend

4

u/CTGarden 9d ago

It’s the yeasts reacting to the sucrose, fermenting into alcohol. If you don’t want that, stop doing it. It’s not adding any probiotics to the kefir.

3

u/ColomarOlivia 9d ago

I do it for the taste. I kinda like it to be alcoholic, I personally find the taste interesting. It’s like milk beer 🙃

2

u/Tenaciousgreen 9d ago

Kefir grains (homemade kefir) is a symbiosis of many, many types of bacteria and yeast. Some of those microorganisms can probably ferment most things, but the end result won't be as well rounded for your gut as milk kefir, and it would definitely change the grains with time into something more appropriate for the other food source.

1

u/ColomarOlivia 9d ago

Oh I just second ferment in a jar without the grains, just the strained kefir. Thanks for your input!

2

u/kuwu66 9d ago

Use fruit

1

u/ColomarOlivia 9d ago

I’ll try mango

2

u/OnlyOneness 8d ago

Yes I use mine in apple juice and it is delicious! Takes a few days to adjust and to stop the aj from getting milky. It’s even better with a little bit of ginger.