I have been experimenting with making the traditional Indian yoghurt dahi based on this recipe.

However, I've been unable to source fresh milk locally and have been using a homogenised UHT brand sourced from Poland which nonetheless has a fairly standard composition of 3.5% fat, 4.7% sugar, and 3.2% protein. By trial and error, I've had to modify the preparation methodology somewhat to obtain satisfactory results.

As both the chemistry (denatured proteins etc) and process are fundamentally different, I'm strapped for the appropriate terminology and chemistry of what I'm making here. Helpful suggestions and observations welcome.

Method: bring 1 litre to the boil then simmer for 15 minutes on a very low flame. Allow to cool to ~40^o C. Add a tablespoon of live culture from previous batch, stir well and leave to ferment for 24 hours in oven heated by oven light (ie around body temperature). Refrigerate.

Products: a) ~ 500 g of a thick white aerated curd that can be spooned off the top. Something between Greek-style yoghurt and Lebanese libneh. Gets more cottage cheesey on cold storage.

b) ~400 g of somewhat cloudy sour whey. As a replacement for water in flatbreads, it makes the dough more workable and elastic. Which is good.

c) residual balance of homogenous white yoghurt, denser than the whey. As far as I can tell, a) + b) = c). Slightly thinner than what I expected for dahi, but it makes a really good lassi.

That sounds like kefir. When fermentation is done, I run it it through a sieve to remove the kefir grains. That process also mixes the solids with the lower liquid. Yours is the same, it just doesn't have the polysaccharide grains that house the bacteria. Basically, it's non-organic kefir imo.

To make kefir, I buy kefir and milk. I drink 90-95% of the kefir, pour fresh milk over the rest, and after 24 hours+ we have a new batch of kefir.

19 hours ago, StringJunky said:

That sounds like kefir. When fermentation is done, I run it it through a sieve to remove the kefir grains.

Can it (product c) at least) be called ''kefir" if kefir grains are not used? My initial starter culture was a spoonful of fermented cucumber brine and a broken dried red chilli. Different bacterial strains and AFAIK no significant yeast involvement.

Other significant differences are the considerably higher fermentation temperature, and the consequently unavoidable (I think) whey separation.

20 hours ago, StringJunky said:

Basically, it's non-organic kefir imo.

A bit of a divisive dismissal perhaps?

😉

16 minutes ago, sethoflagos said:

Can it (product c) at least) be called ''kefir" if kefir grains are not used? My initial starter culture was a spoonful of fermented cucumber brine and a broken dried red chilli. Different bacterial strains and AFAIK no significant yeast involvement.

Other significant differences are the considerably higher fermentation temperature, and the consequently unavoidable (I think) whey separation.

A bit of a divisive dismissal perhaps?

😉

OK. It seems part of kefir's definition is that grains are used and it is lacto and alcohol process. the reason why I thought this was because you can get freeze-dried kefir bacteria, which doesn't produce the polysaccharide complex.

On 1/5/2026 at 5:41 PM, StringJunky said:

That sounds like kefir.

Do you simmer the milk first? I've seen kefir recipes that omit this stage and am wondering if I need to bother with it. The whole point of UHT is that it's already been heat treated and is pretty sterile anyway.

3 hours ago, sethoflagos said:

Do you simmer the milk first? I've seen kefir recipes that omit this stage and am wondering if I need to bother with it. The whole point of UHT is that it's already been heat treated and is pretty sterile anyway.

No, I didn't, using pasteurised, it was fine. I think the culture soon overwhelms any other strains in there. I wouldn't bother heating with uht.

On 1/14/2026 at 4:12 PM, StringJunky said:

No, I didn't, using pasteurised, it was fine. I think the culture soon overwhelms any other strains in there. I wouldn't bother heating with uht.

Tried a one litre UHT batch without heating and got 100% conversion to homogenous yoghurt. Negligible whey separation. Not that I can't find a use for the whey, but it's good to have the flexibility of a choice.

UHT goat milk might also be good if there are any digestive issues not resolved by the fermentation. It has the A2 casein, which some find easier to handle. (A2 beta-casein is what is found in human milk)

11 hours ago, TheVat said:

UHT goat milk might also be good if there are any digestive issues not resolved by the fermentation. It has the A2 casein, which some find easier to handle. (A2 beta-casein is what is found in human milk)

Useful to know. Beginning to suspect my 'inconvenience' may be down to brief fever and course of strong antibiotics over Marxmas. I've never really done allergies and the like (touch wood).

2 hours ago, sethoflagos said:

Useful to know. Beginning to suspect my 'inconvenience' may be down to brief fever and course of strong antibiotics over Marxmas. I've never really done allergies and the like (touch wood).

Antibiotics wreck my gut behaviour for quite some time after the course. I hate taking them.

4 hours ago, StringJunky said:

I hate taking them.

Me too. Apart from the daily Warfarin and a precautionary dab of antiseptic on abrasions, I tend to let nature take its course unless things get scary.