All of the above are deceptively easy, and full of the good bacteria you want in your system - having the right bacteria in there is a contributing factor that has been recognised as a part of keeping 'lean' within the confines of a healthy diet...
Although I 'cooked' my milk in the Thermomix, you don't need one to make yoghurt, or any specialist equipment or ingredients - just an accurate thermometer, milk and a starter (e.g. plain organic yoghurt, which you can buy in little pots for pennies - I like Yeo Valley) will do, and all you need to turn your set yoghurt into Greek-style yoghurt or soft and creamy (yoghurt) cheese is some muslin cloth, as a minimum (although there are more compact ways to do it).
If you just want to get making yoghurt, rather than reading about how not to make yoghurt, then scroll down to the ingredients, to get started, and go to the parts of the method in bold, if you want to skip the 'why' bits! (Well, that's what I'll be doing when I re-visit my own post, to remind me of temperatures, timings etc.!). If you want a shorter Thermomix-only version of this recipe, click here.
The most important element of making your own yoghurt at home (aside from sterilising the container/s you leave it to set in) is getting the temperature right, to avoid grainy, lumpy or runny failures, and the best time to start making it is in the evening, to give the milk time to cool, and then leave the yoghurt to set overnight and put it into the fridge to chill the next morning. [Edit - something else I have found, after confidently perfecting and writing up my recipe for the perfect thick and creamy yoghurt, then trying to make some at a later date with 'reduced' milk - make sure your milk is fresh! Don't use it at the end of its date, or beyond, as you'll see that it turns lumpy when you cook it, even before you try and turn it into yoghurt! Don't be deceived into thinking that if it's on the turn, or even if it still tastes OK but is past the date, that it might make good yoghurt... no!]
The reason I wrote this up, is because I had a few failures (not inedible, but a few lumpy and grainy, and one completely runny - luckily, being resourceful I turned the lumpy ones into Greek-style yoghurt and 'cream cheese' by draining them, and the runny one ended up as banana yoghurt smoothies for the kids!), so I had to try and find out why. I read around, and refined the way I had previously been doing it, to rectify the mistakes, and try and make sure they didn't happen again so it seemed worth sharing to help other people avoid making the same mistakes. Of course, there is always the chance of a dodgy starter culture, or if you haven't insulated your yoghurt well enough and it gets too cold, it might not set, but if you don't kill the milk or the culture in the first place that's certainly a good start!
I started off with recipes from the Thermomix community, and using an Easiyo 'yoghurt maker' (essentially just an insulated container which you put a container of your cultured milk in) as per their instruction booklet but I found that I wasn't getting consistent results. Reading around, I came to the conclusion that going by the instructions I'd been following, a few things weren't quite right - not necessarily all these things were happening every time, and it did work on a couple of occasions, but essentially one or more of the following problems were occurring:-
- the milk was not perfectly fresh (don't use milk at the end of its use-by date or you may find it's lumpy / grainy even after you've cooked it)
- the milk was heated up to too high a temperature too fast
- the milk was too hot when the yoghurt starter was added
- once the yoghurt starter had been added, the milk was 'cooking' to too high a heat for too long
- the boiling water in the easiyo was heating the cultured milk to too high a temperature
This was no good, because there are only so many cream cheese bagels you can eat, with a banana smoothie on the side, so I needed to rectify the problems. So I read around. Including good old Harold McGee, the father of molecular gastronomy and science in the kitchen, who never fails to provide an answer or solution to a culinary problem.
So, how to make perfectly smooth and creamy yoghurt at home, with no added nasties?
1 litre full cream whole milk (Semi-skimmed milk will give you a nice set yoghurt, a bit like the 'French-set yoghurts you can buy, but not as thick and creamy as full fat milk), preferably Gold Top milk from Jersey and / or Guernsey cows, because it's richer, creamier and higher in protein than normal milk (it's around 5% fat, usually), widely available in the UK. If you use homogenised milk, you will get a smooth and uniform result. If you use non-homogenised, you will get the creamy part at the top of the yoghurt, a bit like you get the fat on top of clotted cream, but not so seperate. It's up to you which you prefer. If you don't want to go through cooking the milk, you can use UHT milk instead, and just heat it up to around 35C before mixing in the yoghurt.
50ml / 50g plain organic yoghurt (I like Yeo Valley, which you can buy in small 150ml pots for a few pennies)
Use 50ml / 50g yoghurt set aside from your previous batch (I personally wouldn't do this for more than 5 or 6 batches to try and make sure the right bacteria are still hanging around, although I hear tell some people have been doing it for decades)
I find it's best to start this early evening, as you need up to half an hour to cook the milk, plus potentially up to 2 and a half hours for it to cool if it's in a warm room on a hot summer's day, before you can add the starter and put it aside to set overnight (or just stand it in a bowl of cold water for a way quicker cooling time).
Firstly, you need to heat up the milk (not too fast), and hold it at a certain temperature (These days manufacturers generally cook the milk at 85C for 30 minutes, or 90C for 10 minutes to improve the consistency of the milk by denaturing the lactoglobin so that the casein particles bond together in fine chains, rather than clusters* if you wanted to know the science-y bit!).
In general, warm the milk up gently in a pan, until it hits 90C on a thermometer, and then hold it at that temperature for ten minutes (may require some switching on and off of the gas - remember not to leave it unattended!) - in the Thermomix cook the milk at 10 minutes / 80C / Speed 2 (milk directly from the fridge will reach 80C after about 8 and a half to 9 minutes), followed promptly (to avoid the milk cooling) by 15 minutes / 90C / Speed 2 (it will reach 90C after approximately 3 and a half minutes) to give you 10 minutes of holding it at 90C.
After this it needs to cool down to around 35C for best results (at 30C the bacteria work more slowly and give a finer, more delicate protein network with more strands, which have smaller pores that retain more whey but the yoghurt could take up to 18 hours to set; at 40-45C the milk proteins can gel in as few as two or three hours, but the thick strands readily leak whey*).
Remove the jug from the Thermomix, if that's what you've used to cook your milk, and if you have a sieve big enough to cover the jug (or saucepan you've cooked it in), take off the lid and put the sieve on top. If not, remove the measuring cup, and place a sieve over the lid to allow airflow, but prevent anything getting into the milk. (e.g. flying insects... a moth landed in mine once - turned out nicely though!). Alternatively, you could cover with a clean tea towel or similar to keep the wee beasties.
In a warm climate, it might take as long as 2 and a half hours to cool to this temperature, but far less in a cold room, or if you place it in a basin full of cold water. If you haven't got a clean thermometer (ideally sterile), you will get some indication from the temperature lights on the Thermomix - you need to wait until the 37C light no longer comes on.
Once cool enough, shake off any condensation gathered on the underneath of the lid into the sink, if necessary, and carefully remove and discard the skin formed on the surface of the milk. Add the 50g of starter / yoghurt, and mix in gently with a whisk, or in the Thermomix cook for 2 minutes / 37C / Speed 2.5.
|Easiyo manual yoghurt maker**|
(Click on picture for more details)
Now you need to transfer to a sterile container (e.g. a large jar), insulate it and keep it warm until set. You could use an insulated picnic / cool box (e.g. Esky style) if you have one, and even put a several inches of warm water in the bottom to help it stay warm, or wrap it in foil and a couple of towels and leave it in a warm place. I use an Easiyo manual yoghurt maker, which is essentially like a large thermos which holds your litre of milk in a container (included), with hot water in the bottom, and keeps it warm while it sets. I find it's very reliable, but I don't put boiling water in the bottom, I mix 1 pint (568ml) of freshly boiled water, with 1 pint of cold water from the tap - which gives you water at a temperature of about 47C, which won't upset the yoghurt, but will keep it nice and cosy (after 11 hours, it's 28C, and has done its job) - and pour this in until it reaches the recommended level (which is just under 2 pints / 1,136ml). I would highly recommend Easiyo based on its performance so far, even if it is just a glorified thermos. They're generally just over £10 including postage, and you can find them on amazon here**. I was happy, as after 3 batches of home made yoghurt instead of buying expensive Greek yoghurt, I'd made my money back, plus a little bit more! I recommend leaving for 8 to 15 hours. I find that it is set, but on the mild side by 8 hours. 11-12 hours gives a nice flavour and set, and 15 hours gives a very thick, set yoghurt with good flavour (I haven't gone beyond 15 hours yet). It is very important not to move the yoghurt while it is setting, so put it somewhere it won't be disturbed (especially if you have curious children!).
Once it's chilled, you're good to go. Enjoy it as a topping, with fruit, or fruit compote stirred through, as a healthy alternative to cream, or creme fraiche on the side of desserts or cakes, or however you normally enjoy yoghurt. You will notice that there is some small separation of whey, once you have started to dig into the yoghurt. This is natural and you can just pour it off, and reserve for other uses, such as baking, or adding to soups or smoothies etc.
If you want to go one stage further, you can now strain your yoghurt, to achieve an even thicker and creamier Greek-style yoghurt, or a spreadable soft cheese. This is also a brilliant rescue if you ever have yoghurt which turns out grainy or lumpy.
|Cuisipro® Soft Yoghurt Cheese Maker|
You can strain it for just an hour or two, to thicken up your yoghurt, or from two to eight hours to give a soft spreadable yoghurt smooth 'cheese', and add salt to taste, and optional fresh chopped herbs (e.g. chives), or garlic and parsley, black pepper, a little smoosh of sweet chilli sauce, anything you fancy really!
Make some blinis, and have it on top with smoked salmon, and a little sprinkle of fresh chopped chives or dill, if you're feeling indulgent! If you've strained it, due to a grainy cheese fail, just give it a bit of a vigorous stir with a fork, and you should find that it whips up into a nice smooth cheese (or thick Greek-style yoghurt), and you'd never know!
*McGee on Food and Cooking; McGee, H., 2004, Hodder and Stoughton, London.
**This post contains Amazon affiliate links for the Easiyo yoghurt maker and Cuisipro yoghurt cheese maker. Clicking on the links will simply take you to view the product on Amazon, and not cost you anything whatsoever. Should you decide to purchase the product from the link above, you will not pay a penny extra, but I may get a minute percentage of the proceeds from Amazon. Essentially, it makes no difference to you at all, but go Google them too if you're interested in buying them, to see what the best deal is for you! I only include the links, as I'd be giving you a link to Amazon anyway, as it's the easiest place to find things :)