Homemade yoghurt has a beautiful light and silky texture and creamy taste that sets it apart from the store bought variety, and it is really very easy to make. Here's how ...
1. Pour some milk into a saucepan. I use a medium size saucepan and about 600-800ml of milk which makes enough for about 1 week's worth of yoghurt for me. You will need a thermometer. I use a milk thermometer which is handy because it clips onto the edge of the saucepan.
2. Heat on the stove to 80C or 180F. This kills any bacteria already in the milk. This is the hard part ... 80C is just before the milk boils over and makes a mess so don't forget about it. If it does boil over it will not effect your yoghurt but you lose some milk to the mess on the stove and cleaning milk off the stove is not fun ... yep, I've done it more than once. While it's heating you can add sugar, honey or vanilla if you want a sweet or flavoured yoghurt. When I began making yoghurt I did this and gradually reduced the sugar content as my tastebuds became acclimatised to the lower sugar content. I now just make plain yoghurt, which apart from the reduced sugar has the added bonus that I can use the yoghurt both on my breakfast and in savoury dishes.
3. Turn the heat off. Let the milk cool down to between 38 and 42C (100-110F). This is the temperature the the yoghurt cultures grow at. Too hot and you'll kill your yoghurt bacteria, too cold and they won't grow. If you do forget your milk at this stage and it drops below 38C just turn on the heat again to get it back to temperature. I normally skim the skin that forms when it cools off the top of the milk.
4. Now you need a little bit of yoghurt as a starter. I use a small amount of my previous batch of yoghurt but starting out you can use a store bought yoghurt with live cultures. I've used Jalna and a few other brands. Just make sure they contain live yoghurt cultures and you should be good to go. I use a heaped teaspoon of yoghurt and mix it with a little bit of the warm milk in a small bowl. It's easier than trying to stir the yoghurt into a big pot of milk. Don't go crazy here, if there's still small lumps of yoghurt, that's fine.
5. Pour this yoghurt/milk mixture into a clean container. I prefer to use a pyrex container because it's glass with a tight fitting lid, but plastic tupperware type containers or glass jars would be fine. Once you've done that pour in the rest of the milk from the saucepan and give the whole lot a good stir.
6. Now you want to keep it warm for about 8 hours. I wrap it in a towel and put it into a cooler bag. I used to put a heat pack in the cooler bag as well but then my heat pack spilt and I haven't replaced it. If you've got one you can use it, but it's not necessary. If your house is very cold then you might need it.
7. If you are making the yoghurt in the evening, I often make mine after dinner, you can leave it overnight and your yoghurt will be set in the morning. This batch I made mid morning and put it in the fridge at 8pm. I usually let it set for anywhere between 8 and 14 hours. Once it's set you don't want to stir or shake the container as that will break down the structure of the yoghurt.
And that's all there is to it. Cheaper and yummier than store bought, and much easier to make than you might think. I think my first batch failed, mainly due to the fact that I was trying to gauge the milk temperature by feel but since then I have only had one batch fail and I've been making it several times a month since early last year. If you want to give it a go my recommendations are to use a thermometer and if a batch does happen to fail, buy new yoghurt to use as a starter.