Thermophilic starter cultures are used mostly by the pasta-filata and cooked curd cheeses. Here is a simple recipe to produce an easy thermophilic culture at home.
- Start with 2 cups of FRESH milk. Heat it to 85°C on the cook top or in a microwave. Be careful not to heat too high otherwise the cream will separate.
- Let the 2 Cups of milk cool to at least 52°C.
- Add one table spoon of FRESH yogurt either homemade or store bought “live and active culture” type. Probiotic yogurt can also be used.
- Mix the yogurt into the milk thoroughly with a fork or a whisk.
- Keep the mixture at 44°C for 8-10 hours until a firm yogurt has set. This can be done by using a double boiler on a low setting or by placing the inoculated milk into a small CLEAN mason jar placed in a warm water bath. The bath can be kept warm by placing it on an electric range top at the lowest possible setting (so that ‘ON’ light is just on). Monitor the temperature closely the first few times you do this and you will become a better judge of the temperature settings of your range top. This way with future cultures you can set the process up and not worry about it for 8-10 hours. Alternatively, you can use an electric yogurt maker.
- Pour this culture into a full sized CLEAN ice cube tray and put into your FREEZER. As with all steps of cheese making, cleanliness is next to godliness.
- Once frozen, remove the cubes and put into a CLEAN sealed container or plastic freezer bags. It is a good idea to label the container to distinguish it from your mesophilic culture.
The resulting ice cubes are each 30 ml of thermophilic starter. Add these cubes (thawed) to your recipes as required. The cubes will keep for about one month. To make more starter culture again simply thaw one cube and use it as the fresh yogurt used in step 3.
One another way is to use kefir as thermophilic culture (here is the discussion I’ve started on Cheese Forum) . Kefir has got a lot of bacteria and yeasts that can be used as starter culture. If you follow the thermophilic starter procedures and use Kefir instead of fresh milk, you would be getting a good and strong culture ecosystem. Strain about 1 liter of Kefir (separate the gems) and use your yogurt maker or keep the temperature about 43°C to 50°C for a day. This will eliminate most of the mesophilic cultures and some yeast. When it is curdled like yogurt (about a day or 2) separate 500 ml and mix it with 500 ml skimmed pasteurized milk. Put in your temperature controlled yogurt maker and keep it 43°C to 50°C constant till it curdles again. If you do this for 7 to 10 times, you will get a strong thermophilic ecosystem with lots of different thermo bacteria. I am using this starter for some hard cheeses and feta mainly. It does have gas producing bacteria in ti and cheese ends up with holes. Aroma and texture is also very good.