Dehydrating AND rehydrating yoghurt?

[Drew]

I've been wanting to try this for a while to make my muesli a bit more interesting when on a hike. There's lots out there about dehydrating yoghurt, but it seems almost everybody eats it as a snack in its dried form (flavoured yoghurt presumably).

Does anyone have any experience rehydrating it to eat like real yoghurt?

I've read in a few places that you shouldn't use full fat yoghurt as it will go rancid easily. I hate to use the reduced/low fat version of anything, so if someone can dispel this notion I will be pleased!

Cheers

[walk2wineries]

No. But years ago I suggested using packet mix-with-water and leave overnight yoghurts (mixture of culture and powdered milk I think) to the CradleHuts people and last time I went they were doing that. The fullfat Greek yoghurt is very good. Would take a bit of trial and error but I would expect that it could be mixed with warm water and left in a Nalgene and a cosy overnight - or even double wrapped and put into one's sleeping bag. I think the packets are about $4 from supermarkets and K-mart.

[whynotwalk]

Not quite the same, but I dehydrate my Bircher muesli, which includes yoghurt and stewed fruit mixed in with the juice-soaked muesli. It rehydrates well, with no rancid taste to the yoghurt. It ends up more like a very fancy porridge than Bircher muesli, but I'm very partial to it,

cheers

Peter

[Drew]

Thanks guys. The bircher muesli isn't a bad idea - except I'm not a big fan of bircher muesli! Maybe I'll try it in future though. Do you rehydrate with hot water in the morning or do a cold dehydrate overnight? It would be good hot on cold mornings.

I think I'll try just dehydrating some real yoghurt with honey mixed through tonight and then I can test the rehydration tomorrow morning. At least with some honey for sweetness it might still be an edible snack if the rehydration doesn't work out.

[whynotwalk]

Do you rehydrate with hot water in the morning or do a cold dehydrate overnight? It would be good hot on cold mornings.

I've done both Drew. It's quicker to cook if it's soaked overnight, but it really doesn't take long if you just add hot and cook it in the morning. I always have it warm though ... and maybe that would help overcome your dislike of Bircher. The key is to add ingredients you REALLY like (eg stewed apple, or pulped mango, or mooshed raspberries).

I think I'll try just dehydrating some real yoghurt with honey mixed through tonight and then I can test the rehydration tomorrow morning. At least with some honey for sweetness it might still be an edible snack if the rehydration doesn't work out.

Let us know how it goes. My guess is it won't be as smooth as the original, but it should still be better than just edible

cheers

Peter

[Snowzone]

When I dehydrate my hummus, I then grind it into a powder form and store. Then to rehydrate just mix the required amount with water and let stand 5-10 minutes and is ready. I would think yoghurt might work the same?

[icefest]

I think the nalgene culture in the sleeping bag would work quite well. I'm tempted to try it myself.

[Drew]

Well, the yoghurt rehydration was a moderate success.

I added hot water to the dried yoghurt in a zip lock bag in the evening, gave it a good massage to dry to break it up, then left it overnight. In the morning it in no way resembled the yoghurt that it once was. Instead, it was a liquid a bit thicker than milk, like drinking yoghurt. Poured onto toasted muesli with some chopped apple it tasted pretty good - a bit sour like yoghurt, with the sweetness of the honey I had added. Better than powdered milk I reckon, but not sure if it's worth the effort. I'm curious to know why it didn't get thick again. Did the dehydration kill the culture? Or the hot water during rehydration?

Oh, and it wasn't possible to grind the dehydrated yoghurt into a powder - it was quite rubbery in texture, presumably due to the high fat content.

[north-north-west]

Wonder if you could do something like this with pickles . . .

[Orion]

I'm curious to know why it didn't get thick again. Did the dehydration kill the culture? Or the hot water during rehydration?

I was wondering if there were a chance you'd have success. It seemed unlikely to me. By the time yogurt has finished fermenting and is ready to be chilled the bacteria have done their job, converting milk sugar to lactic acid which in turn curdles the milk. If you could look closely enough you'd see a kind of sponge made up of sub-micron proteins stuck together holding the liquid portion in place: a gel. There is a step in yogurt making where the milk is first heated to about 85-90°C. This is done not so much to kill unwanted bacteria but rather to denature these proteins in just the right way so that later when the pH drops they will stick together a little bit but without clumping.

When you dehydrate this delicate structure it seems very probable to me that the solids will be further denatured in an irreversible fashion. At least that's what I imagine would be the case. I don't really know. Sometimes it's easier to just do the experiment.

Have you tried buttermilk powder? I know it's not exactly the same thing. I ask because buttermilk is what I prefer on my müseli at home, since the texture isn't too thick like many yogurts. Reconstituted powdered buttermilk might not return to its original texture either.

[Drew]

Have you tried buttermilk powder?

No, but that sounds good. Can you get it at the supermarket? At home I like my yoghurt thick and creamy. I add some milk too. I've been making home made yoghurt lately (it's what I dehydrated) and have struggled to get it as thick as I'd like.

I think though that I'll try the dehydrated bircher as suggested by whynotwalk for my Easter adventures.

[Snowzone]

Well, the yoghurt rehydration was a moderate success.

I added hot water to the dried yoghurt in a zip lock bag in the evening, gave it a good massage to dry to break it up, then left it overnight. In the morning it in no way resembled the yoghurt that it once was. Instead, it was a liquid a bit thicker than milk, like drinking yoghurt. Poured onto toasted muesli with some chopped apple it tasted pretty good - a bit sour like yoghurt, with the sweetness of the honey I had added. Better than powdered milk I reckon, but not sure if it's worth the effort. I'm curious to know why it didn't get thick again. Did the dehydration kill the culture? Or the hot water during rehydration?

Oh, and it wasn't possible to grind the dehydrated yoghurt into a powder - it was quite rubbery in texture, presumably due to the high fat content.

At least it still tasted ok for you and wasn't a complete failure. If you feel like another attempt try adding cold water and leaving overnight rather than hot water. Thanks for your experimenting anywayz.

[Drew]

If you feel like another attempt try adding cold water and leaving overnight rather than hot water.

The reason I used hot water was because I thought it would be necessary to break down the fat in the yoghurt. It seemed that with cold water the rubbery dried yoghurt would have just sat there, protected from absorbing any water by the fat.

[Orion]

I have seen powdered buttermilk in supermarkets but can't be certain how easy it is to find. I believe people use it for baking which likely means it doesn't return to the same texture as freshly fermented buttermilk.

As for the yoghurt, my guess is that the rubbery texture is due to the coagulated proteins, not the fat. Have you ever made fresh curds? They're rubbery even when made with non-fat milk. One other approach you might try (out of desperation) is to use a thickening agent, like gelatin. It's hard to imagine that will turn out all that well though.

[dnaylor]

1.if you are going to the trouble of making yogurt by buying the easiyo or hansels or aldi brand DIY ones then it would be more fool proof if you bought the yogurt maker to go with them... it (the easiyo one) uses hot water and no power...
2.just mix the powder with water and drink as a shake or use instead of milk powder (more expensive than milk powder but you get the cultures) as all the cultures are realy doing is thickening the mix....

btw.. on a side note i have seen powdered goats milk in Woolworths but at $20+ a kilo you'd really want to need it over ordinary milk...

[dnaylor]

If you feel like another attempt try adding cold water and leaving overnight rather than hot water.

The reason I used hot water was because I thought it would be necessary to break down the fat in the yoghurt. It seemed that with cold water the rubbery dried yoghurt would have just sat there, protected from absorbing any water by the fat.

Ahhh... ok...when you dry out yogurt you are basically making a form of cheese and that is not going to reconstitute... its like trying to add water to Haloumie cheese...

you can actually buy a very fine mesh basket and container system and after adding a kilo of plain yogurt and leaving in the fridge for 24hrs you get about 400g+ of something like firm ricotta or a cream cheese which is really nice on raisin toast...

[gayet]

you can actually buy a very fine mesh basket and container system and after adding a kilo of plain yogurt and leaving in the fridge for 24hrs you get about 400g+ of something like firm ricotta or a cream cheese which is really nice on raisin toast..

This is called labne and is very useful. The longer you leave it to drain (use a new rinsed chux in a colander if you don't want to buy anything specifically) the firmer it gets. Use it instead of butter or marg on raisin toast with a drizzle of honey and its heaven. On bread/crackers instead of butter marg with salad stuff and you have the cheese and mayo in one.

[walk2wineries]

Yes, the Easy-Yo or the very similar Aldi one were what I was thinking of. At home, you mix with cold water (I use milk to make it richer) and put the whole thing in a thingy like a plastic thermos, half filled with boiling water, which is supposed to keep it lukewarm overnight. The whole thing is the size of a football which is why I suggested maybe mixing it with warm water and tucking it up in your sleeping bag or under your armpit overnight.
I wonder if its worth trying the cooking yoghurt (Danoz and other brands, its separately labelled, look for it) - which has been stabilised so that when its added to curries etc its less likely to curdle. No idea how that would affect drying. I've stopped making any since nice thick Greek Yoghurt became a staple in the supermarkets.

[gayet]

Easier and possibly cheaper -

1 x Food size thermos flask (or lidded glass jar and towels)
required volume of milk
good dollop of FRESH natural yogurt.

Warm milk, stir in yogurt, mix well.
Poor into warmed flask or jar, screw on lid loosely, wrap in towels to keep warm. Leave overnight.

Next morning you have yogurt. But you need to start with a small tub of the freshest natural yogurt you can find. Must be natural, greek style sort, not flavoured.
This can be drained for labne, flavoured as you wish or whatever. Use a dollop of this to start your next batch. Every so often it is worth going back to the small tub of commercial yogurt as the starter to renew/strengthen your culture. You can also buy small vials of culture from cheese manufacture suppliers.

[Drew]

We've been making yoghurt at home for a while with culture that we bought from a local shop. It's hard to get it quite as thick as a Jalna greek yoghurt, but the flavour is very good. I tried the Easy-Yo and thought it was yuck and expensive - I think the sachets cost $4 or $5 to make 1 litre. You can but 2kg of Jalna for $10! The culture we use only cost around $15 and makes around 30 litres of yoghurt (although you have to buy milk too, unlike the Easy-Yo). When we run out of the culture maybe we'll try using shop bought yoghurt as a starter.

[flywire]

The Easy-Yo sachets demonstrate that the culture can be dehydrated and added to powdered milk to make yoghurt. The only other dried yoghurt culture I have seen was part of a very expensive kit in a health food store.

I had problems keeping the temperature right with home made yoghurt so I bought an Easy-Yo container. I shake 1l of UHT milk with a good spoon of yoghurt from the previous batch and place the container in the hot water within the Easy-Yo container then remake another batch within a week. I have also made it directly in the UHT milk carton. The UHT milk is heat treated which denatures the whey proteins, improving the yoghurt texture, without needing to heat and cool the milk. The original starter culture I used was natural Greek style yoghurt and although the top of my yoghurt approaches this consistency on the second day after cooling in the refrigerator it never exceeds it. If it gets too hot, cold or is left for too long the consistency is adversely affected. I have been told that you can also use powdered milk mixed to milk consistency. After buying the Easy-Yo container and starter it costs $1/l (=1kg).

As I see it it would be feasible to make yoghurt while camping if the temperature can be managed, say in the shade during a summer day.

[walk2wineries]

yes, that's why I suggested a Nalgene bottle in the sleeping bag at night - should be about right, ie dispense with the EasyYo insulated thingummy. Anyone tried it?

[corvus]

This topic has me intrigued , effort and energy to achieve this why ? it is not as if yogurt is an an essential foodstuff,I much prefer to use that energy to produce Jerky as a much better bang for the Buck .

[GPSGuided]

Human diversity.

[corvus]

Yes I guess to each their own

[perfectlydark]

My kids eat these things from woolies called 'yogurt dots'. Cost a fortune and havin a look at them, its just dehydrated yogurt. So on the weekend i cracked out the dehydrator and dehyd some yogurt. I used those kids squeeze tubes so can easily put many little dots of yogurt. Great success! Kids loved the result, i did too. Has similar taste and texture as those fruit rollup things.
I might do a full batch now

[flywire]

Here is an instructable demonstrating the technique: http://www.instructables.com/id/Dehydrate-Yogurt/?ALLSTEPS

[Orion]

Here is an instructable demonstrating the technique: http://www.instructables.com/id/Dehydrate-Yogurt/?ALLSTEPS

Oh, so it actually can be rehydrated to something resembling yogurt?

"To re-hydrate to yogurt-like consistency, add about 2-3
ounces (60 - 90 ml) of water to one ounce (30 grams) of powder, mix well, and
let set for 10-20 minutes. The result will not be as smooth as the original yogurt,
but will be as tasty."

I'll have to give it a try.

[flywire]

Oh, so it actually can be rehydrated to something resembling yogurt?

Why bother? Just make a new batch using this as starter with water and powdered milk.

[Orion]

Why bother? Just make a new batch using this as starter with water and powdered milk.

I don't want to sleep with a container of milk.

Instant milk powder combined with a low temperature, agitated incubation might not produce that high quality a result anyway.