The origins of yoghurt are unknown, but it is thought that milk may have become unintentionally infected through contact with bacteria, transferred via the udder of a domestic milk-producing animal. The bacteria sets the milk into yoghurt curd, converting the lactose in whole milk to lactic acid - this is why those who are lactose intolerant can eat yoghurt.
Making your own yoghurt is easy and complicated at the same time. It's easy because you only need whole milk and a small amount of yoghurt. The complication is that you have to be meticulous with your equipment sterilisation and temperature control. But once you taste the finished product the effort is worth it.
Raspberry and yoghurt loaf is a very moist cake. It is fantastic for morning tea and makes an excellent dessert when served with some of your favourite ice-cream. You can replace the raspberries with blueberries or strawberries.
1 litre full-cream milk
2 tbsp natural yoghurt
You will need jars with lids to hold the yoghurt, either one large jar that holds 1100 millilitres, or some smaller jars. Fill a large saucepan with water, place the jars, lids, a whisk and metal spoon in the pan, bring to the boil then boil for 10 minutes. Turn off the heat and leave everything in the saucepan until you use it.
Pour the milk into a smaller saucepan. If you have a thermometer, clip it to the saucepan and heat the milk to 90C. Take the milk off the heat and let the saucepan sit in a sink half filled with cold water, to cool the milk quickly.
When the milk reaches about 35-40C but no higher, add the yoghurt and whisk in thoroughly. Adding the yoghurt to the milk when it's too hot will kill the beneficial bacteria but you need the milk to be warm enough to activate the bacteria, so make sure it's within that temperature range.
Taking your time to whisk the ingredients thoroughly gives you smooth yoghurt. When the yoghurt is ready, take the sterilised jar or jars out of the water and place on the kitchen bench to cool down slightly. While the yoghurt is still hot and the jar is still warm, add the yoghurt to the jar and seal the lid. Place the sealed jars in a small esky or similar container and fill it with warm water to a level three-quarters up the sides of the jars to keep them at 35C. Check every so often to make sure the water is still warm; replace with more warm water if it has cooled. Leave in the esky for nine hours. When you take it out, the milk will have set. Chill the yoghurt and it will thicken further. It will keep for a week in the fridge.
250g plain flour
2 tsp baking powder
pinch of salt
115g soft butter
255g castor sugar
zest of 1 large lemon, finely grated
2 large eggs
100g full-fat plain yoghurt
25g ground almonds
200g fresh raspberries
1 tbsp white sugar
Preheat the oven to 180C. Grease a 23-centimetre loaf tin and line with baking paper.
Sift together the flour, baking powder and salt.
Cream the butter and castor sugar in a large mixing bowl for five minutes until pale and fluffy, then beat in the lemon zest. Beat in the eggs one at a time, adding a tablespoon of the sifted flour with the second egg. Alternatively fold in large spoonfuls of the remaining flour and the yoghurt until the mixture is smooth, then fold in the almonds.
Spoon one-third of the cake mixture into a loaf tin and scatter with one-third of the raspberries. Repeat twice, finishing with a layer of raspberries.
Bake for 45-50 minutes until the cake is nicely browned, then cover loosely with foil and bake for a further 20-25 minutes, until a skewer inserted into the cake comes out clean.
Remove the cake from the oven. Cool for five minutes. Sprinkle with white sugar. Carefully remove the cake from the tin and put it on a wire rack to cool. Serve in thick slices.
When choosing which jars to use for making yoghurt, make sure they will fit in your incubator (eskyor similar container) before sterilising.