Hacker News Reader

Comment by gnicholas | Hacker News Reader

What was your original culture from, and how often do you start fresh? Do you strain? What do you store a gallon of yogurt in after you make it?

I make 1/2 gallon at a time and strain with a cheesecloth for a couple hours. The output fits into a large round pyrex container.

View on HN

I second these questions. I use the Greek yogourt from a local dairy shop as starter and the results are amazing, but I have never been able to use my yogourt as starter for the next batch, no matter how fresh it is.

Just to clarify, I have been able to use one batch to start the next. I've used various yogurts from Whole Foods (2% or whole, but always plain/unflavored).

My first culture lasted through about 15 cycles (8 mo) before developing a weird blue cheese odor/flavor. When I started again, I also noticed the first batch of the new yogurt was substantially thicker than the last batch of the old yogurt.

Do you guys boil the milk before adding the culture?

Yup. Boil, let cool to 115F, add culture or frozen cube of previous yoghurt, into the instant pot for 9 hours.

I don't boil it, but I heat to to 72°C/162°F for at least 15 seconds, i.e. the recommended temperature and duration for pasteurization.

I just use the functions on my Instant Pot. The "Boil" function brings it to around 180°F. Then I let it cool to between 90-115°F before adding the yogurt. Then use the "More" function and it sets a timer for 12 hours ("Less" goes for 24, and I've never used it). All of these functions are available under the yogurt button on the Instant Pot.

My understanding is it may be possible to skip the boiling if you are using ultrapasteurized milk (lactose-free milk often is) from a just-opened container.

I used to scald milk (in an Instant Pot this is the yogurt "high" setting) before making yogurt, but no longer do so.

Now I buy UHT pasteurized milk, which encompasses most organic milk, and simply run 18 hours of the Instant Pot "medium" setting. I start the instant pot, add two half gallons of milk, then pour in some Bulgarian yogurt as a starter and stir, then lid on and leave it alone until it beeps at me.

I normally get around three gallons of yogurt out of a one quart jar of the Bulgarian, which comes in a conveniently Mason-threaded quart jar, where I hoard the leftovers for storing my own yogurt.

18 hours?! I’ve never heard of that for making yogurt. Is that a low temp pasteurization?

I’ve only done the usual 180F, followed by waiting for it to cool, finally add the starter and mix.

When I try to use UHT milk, I usually fail in making yogurt. But that may be because I do 6.5 hours and he's doing 18 hours. Perhaps you need to go so long with UHT?

Well he probably uses a machine (yaourtière in French) which maintains the pots at 40 degrees. My parents use this with UHT to do yoghourt.

Why did you switch from scalding regular milk to UHT? 18 hours is a long time to make yogurt. I do the scalding, let it cool in a fridge for an hour, and then make yogurt for 6.5 hours. This works for non-UHT milk (doesn't for UHT).

Not OP, but I've found that using UHT (or semi-UHT as many refrigerated organic milks are in Australia) works just as well as a heat->cool of non-UHT (after all, UHT is just milk that has been heated then cooled). So it's less work/fussing around/friction, and I end up making yoghurt more often. I usually do a 12 hour cycle. The heating (either at home, or via UHT) is necessary to modify the proteins so it thickens.

Interesting. For me (in the US), UHT was usually a failure - but as I said, I do it for only 6.5 hours. I could try doing it for longer, and I guess that's convenient for overnight. But otherwise, heating + 6.5 hours for regular milk is faster.

What I don't understand is: Why does heating + 6.5 hours work for non-UHT milk but not for UHT? It's not just me - I Googled at the time and many others had the same experience: UHT milk often fails. Like me, they all were doing 6-8 hours.

Googling now, I see lots of people arguing if UHT makes it harder to make yogurt or not. Personally, I'd like to see examples of people making decently thick yogurt (without straining) in under 7 hours with UHT (whether they scald or not).

This site[1] says there was a study done that showed unheated UHT was runnier than heated non-UHT. I didn't check the study to see how long they set it for.

This site[2] also points out that UHT for 10 hours was still quite runny. They had to add powdered milk to get it thicker.

[1] https://www.healwithfood.org/recipes/uht-milk-homemade-yogur...

[2] https://www.everynookandcranny.net/instant-pot-uht-milk-yogu...

So I haven't tried actual UHT; I use 'ultra-pasteurised' organic milk, which is refrigerated, but has a much longer expiry date than you would expect from milk, and you can taste the extra heat treatment. 8 hours works great and gives a thick yoghurt (haven't tried less than that; usually do overnight so around 12 hours). It does tend to get progressively less thick generation after generation. I use a supermarket organic plain yoghurt as a starter (there's a certain ratio of starter yoghurt to milk required - I use 4 Tbsp yoghurt to 1L milk)

The trick I've used is that I freeze cubes of the first batch in an ice-cube tray. Then whenever I make more, I unfreeze a cube, so I'm always making a "second generation" batch. My first generation I make from packets you can find online for ~$1.

Could you please post a link to the starter you use? I would truly appreciate it.

I've used this stuff https://www.npselection.com/products/yogurt-starter-cultures...

and also their Bulgarian style. Also available on amazon I believe. Balkan stuff is very neutral, rich. Bulgarian has a bit more tartness to it.

Thank you.

You might like to try kefir grains. They are very stable, I've had the same grains for 5+ years, and you can leave in the fridge for months if you like.

I used to use dedicated yogurt culture, but "kefir yogurt" tastes exactly the same to me, so I use it for everything (yogurt, goat cheese, kefir-the-drink, obviously).

Here's some more info: https://www.chelseagreen.com/2021/natural-yogurt/

Thank you for the recipe. I don't think I'll ever make it that way though. Stirring the milk non-stop until it reaches 185°F and then continuing to stir if for another hour is much more work than I'm willing to put in.

Milk kefir usually doesn't require any temperature control, it just goes faster when the ambient temp is higher. I believe the idea is that the kefir 'team' is able to easily outcompete any weed microorganisms. For me it's as simple as: Strain in plastic colander, rinse jar, put grains and fresh milk in jar, then place in cupboard. If I want to delay then it can be placed in the fridge instead for months/years and still be able to be revived later.

Apologies, should have read the link.. which is indeed about following a yoghurt-like process using milk kefir grains! But you don't have to do it that way, it can be really easy!

That's great. If you don't mind, I have two follow-up questions:

1. I believe kefir is usually the same consistency as buttermilk, not yogourt. How do you make them as thick as yogourt?

2. How do you keep your kefir grains alive? I don't use a huge amount of yogourt. Can you freeze grains between uses? How often do you need to make a new batch to keep the grains alive?

you strain the grains and add them to fresh milk every day. you can get them to make less by dividing the grains and tossing or eating some. It will get pretty thick if your bacteria are chugging out acid. My kefir would always end up not sour after a week or so. I could revive it for a bit by adding some lifeway kefir, but the ambient temp favored the yeast. A less cold fridge might let the grains run and favor the bacteria to keep it sour. Also lifeway kefir makes a good yogurt starter.

Thank you.

Yeah Kefir is usually only slightly thicker than buttermilk, but it can be strained to make it thicker. It doesn't form solid curds like yoghurt though, but has its own particular fractal-y curd structure.

When not in use I just put the jar in the fridge (as long as it's only been at room temp for <24h) and it can stay there for weeks slowly getting more sour. At some point the kefir becomes too sour to be palatable, but will recover just fine after a feeding or two. I also keep backup grains in water in the fridge for years and have revived one of those after 5 years or more! Apparently the grains can also be dried and revived after years as well but I haven't tried that.

There's lots of info about milk Kefir on Dom's Kefir In-Site (straight from the nineties web!):

http://users.sa.chariot.net.au/~dna/kefirpage.html

I make a batch of kefir every few days. I just use UHT milk, which has already been sterilised in the pack.

It's usually just a 5-10 minute affair for me to strain out the fermented kefir and add a new pack of milk to the grains.

If you know any Indian family ask them. Most Indian households make yogurt every day and the culture is months even years old. They will use latest generation to make the next batch.

Here's my lazy technique.

Get the biggest thermos flask you have. Get as much milk as it fits.

Get any yogurt. So far literally anything has worked: flavored, with added sugar or even the cheap versions with lots of gelatin.

Heat the milk around until it boils. Add sugar until it's slightly sweet but not too much (this will feed the culture. It won't be sweet after). Let it chill until 40c or slightly above body temperature.

Now mix in the yogurt, you need like 6 teaspoons for a liter milk, but just pour the container you have for good measure.

Pour the mix in the thermos flask and leave for aprox 4 hours, or until the whey separates. After that, the longer you wait the more acidic the yogurt gets.

Now time to strain. I put a sheet of coffee filter paper on the bottom of a pasta colander and another container beneath to collect the liquid. Pour the yogurt there, leave overnight in the fridge and you get thick Greek yogurt.

Any one dollar plain yogurt from the supermarket works fine

Keep an eye out for faint orange "oil spills" on the surface or fizziness in the final product. Toss it if you encounter those and start over.

> Any one dollar plain yogurt from the supermarket works fine

A surprising number use additives to thicken them, and as I result I found I got better results from ones labeled Greek or acidophilus. I have no idea if there is any science behind this claim, so YMMV.

I've had a lot of success with plain Kirkland greek yogurt but most should work. I also do 1 gallon at a time and microwave it to get it up to temperature. This takes about 20min from fridge to desired temperature. After fermenting in my instant pot, I pour it into a fine mesh strainer on top of a large food container and put it in the fridge. The container is for the whey to collect in. This turns it into Greek yogurt.

I got a powder culture from Amazon because I am using raw milk and it would just not work with yogurt from the store. There are several different cultures available in 10 or 12 sachets and you might need a new one every 6 months or so. I tried a few different ones and I cannot feel the difference between them.

I've used Tillamook and brown cow as starters and they've been fine for a second batch at least.

I don't strain mine, instead i chuck in like half a cup/gallon of dry milk. It's sort of the bass ackwards method. Then I part it up into quart Tupperware.

Reply on news.ycombinator.com