It is the most common experiment in the fermentation world. You have too many milk grains, and you want to know: Can you convert kefir grains from milk to water?
The internet is full of conflicting advice. Some say yes, science says no. The truth? You can force them to survive for a few weeks, but you cannot truly convert kefir grains permanently. Here is why these two cultures are biologically incompatible.
📚 Grain Knowledge
🧬 Biology: Why You Cannot Convert Kefir Grains
To understand why the attempt to convert kefir grains fails, we must look at the biology.
- Milk Grains (Kefiran): The structure is made of a polysaccharide called Kefiran combined with milk protein (Casein). It is designed to digest Lactose.
- Water Grains (Dextran): The structure is made of a cellulose-like matrix called Dextran. It is designed to digest Sucrose.
According to scientific definitions, the bacterial composition of these two SCOBYs is distinct. You cannot simply swap their food source and expect them to thrive.
It’s like trying to teach a Lion to be a Vegetarian.
It might eat the lettuce to survive for a week, but it won’t be happy, and it won’t grow.
🧪 The “Conversion” Experiment Timeline
What happens if you actually try to convert kefir grains? Here is the typical timeline of a failed experiment.
| Stage | What Happens | The Result |
|---|---|---|
| Week 1 (The Shock) | You rinse milk kefir grains and put them in sugar water. The residual bacteria ferment the sugar. | It fizzes! You get a drink that tastes like a mix of sweet water and sour whey. |
| Week 2 (The Starvation) | The grains stop growing. They begin to turn translucent and brittle. They are shedding their casein coating. | Weaker drink. The fermentation slows down. The kefir grains are entering survival mode. |
| Month 1 (The End) | The grains disintegrate into sand-like dust. They failed to build a new “Dextran” home. | Death. You are left with mush. They never turned into clear crystals. |
🚀 PRO TIP: How to Cheat (The Whey Soda)
Do you want a clear, fizzy fruit drink but only have Milk Grains? Don’t kill your grains trying to convert kefir grains. Use their Whey instead.
The Method:
1. Make normal Milk Kefir.
2. Strain it to get Kefir Cheese. Keep the yellow liquid (Whey).
3. Add 1/4 cup Whey to 1 liter of Fruit Juice.
4. Ferment on counter for 24 hours.
The Result:
You get a probiotic, fizzy soda that looks like Water Kefir, but you saved your grains! This is the smart way to use excess milk grains.
🗣️ What the Forums Say
We scoured Reddit and Fermentation forums so you don’t have to. The consensus is clear:
- The Optimists: “I did it! It worked for about 3 weeks, then they turned to mush.”
- The Purists: “It creates a weird flavor. Not quite water kefir, not quite whey. Just buy the real crystals.”
- The Science: “Lactobacillus kefiranofaciens (milk) cannot synthesize dextran (water crystal structure). It is biologically impossible to convert kefir grains structure permanently.”
Why try it then?
People usually try this because they have excess milk kefir grains and don’t want to spend money on Water Kefir grains.
Our advice: Don’t waste your time. Water Kefir grains are cheap and last forever. Buy the right tool for the job.
❓ Conversion FAQs
Can Water Kefir Grains ferment Milk?
Absolutely NOT. If you put water grains in milk, they will vanish. They cannot process the proteins and fats. You will end up with spoiled milk and dissolved grains within 24 hours.
Do they have the same probiotics?
No. They share some Lactobacillus strains, but Milk Kefir is much more complex (50+ strains) compared to Water Kefir (15-20 strains). Milk kefir is generally considered the stronger probiotic.
Why do some blogs say you can do it?
Because technically, the milk grains will ferment sugar water for a short time (survival mode). Bloggers often write the post during “Week 1” of the experiment, but fail to update it when the grains die a month later.
Can I put Milk Grains in Juice?
Yes, momentarily. They ferment juice very well, but the acidity will eventually hurt them. If you do this, alternate batches: 1 batch Juice, 2 batches Milk to heal them.
What about Coconut Milk?
This is the exception! Milk grains work surprisingly well in Coconut Milk because it is thick and fatty, mimicking cow milk. They won’t grow, but they survive longer than in water.
Will the “converted” grains eventually turn clear?
No. Milk grains are white/creamy and opaque. Water grains are clear crystals. Even if you try to convert kefir grains, milk grains will never turn into clear crystals; they will just crumble into white dust.
Is it dangerous to drink the experiment?
It’s not usually dangerous, but the taste can be off-putting. Without the proper matrix, wild yeast might take over, creating a “funky” or medicinal taste.
How much do Water Kefir grains cost?
Very little. Usually around €10-€15. Considering they reproduce infinitely, it is a much better investment than ruining your milk grains.
Can I use Soy Milk?
Yes, Milk Grains ferment Soy Milk reasonably well because of the protein content. It works much better than water.
I rinsed my milk grains in water, are they dead?
A quick rinse won’t kill them, but it removes their protective slime (kefiran). Put them back in fresh milk immediately, and they should recover in 24 hours.
Ready to Learn More?
Stop experimenting and start fermenting properly:
- The Real Deal: Authentic Water Kefir Recipe.
- The Science: Milk Kefir Bacteria vs Yogurt.
- Flavoring: Best Water Kefir Flavors.
- Troubleshooting: Why is my Water Kefir Flat?.
- Storage: How to Store Both Kefir Grains.
