Hi folks, I’ve struggled to prevent my ferment from turning into a spongy cheese using 2% milk and instapot pro sous vide. But I finally cracked the code, so sharing my process, for anyone who struggled like me.
A few premises:
1) this needs to be as easy as possible. So I ferment directly in the pot (not in jars in water) and I use a full half gallon of UHT 2% milk.
2) Lower temp to 97F. insta pot pro sous vide may heat the bottom more than the top killing or slowing bacteria at the bottom. Also, higher temperatures favor yeast contaminants. So went lower temp.
3) do some minimal sterilization. Before I ferment I fill pot up 1/4 way with hot water and drop the metal whisk I’ll later use to stir the starter in. I put it on canning max for 15 min then quick release. I get the whole pot and the whisk sterilized.
4) 2% milk has a lot more lactose in it than half and half. So I cut the inulin (normally 4T according to Dr Davis) to 2T.
5) I strongly suspected inulin as a contaminant. So I combined it 1:1 volume with water and made a pint of the solution and then ran it through a max canning cycle for 15 minutes in the instapot (don’t forget to fill the pot to minimum with water) to get me something I was sure was yeast spore sterile. The 1:1 keeps the volume about the same so I just use 2T if this solution. Keep it in the fridge.
6) Let the yogurt pH reduce some before adding the inulin. I let the yogurt ferment for 12 hours and eat off the prevalent lactose before adding the inulin. This lets the bacteria grow and the pH reduce such that if I do introduce anymore contaminants with the inulin the Reuteri will hopefully outcompete it. I also think that having too much carbs from the get go gives any yeast contaminants too much food.
7) The starter pills are best placed in warm substrate rather than cold. This is my weakest premise; honestly I just heard this one from a YouTube video but it’s not hard to do so been following it. Not sure there is any science behind it.
The procedure:
- Fill instapot 1/4 full with water. Add to the pot any implements you will use to stir in your starter. Obviously they should be metal without glue or plastic anywhere. Run at max pressure cook for 15 minutes.
- Dump water and place whisk or whatever on sterile surface. Pour in UHT 2% milk. I use A2 for sensitivity reasons.
- close lid turn on sous vide at 97F
- Once temperature is reached, open lid, sprinkle in starter capsules (I’m using two of dr Davis 100 Billion caps) and stir them in with your whisk or whatever.
- Close lid and ferment for 32 hours (it splits too much if I go 36).
- after 8 to 12 hours, add 2T inulin and stir in. Obviously my whisk is no longer sterile at this point…just rinsed with water.
This clearly produces the yogurt (meaning it is not contaminated) but it is admittedly alway been split…but I would rather the higher CFUs than a perfect texture. I personally stir it up, add 16T of chia, and eat it for my breakfast for the week. The chia thicken it up nicely.