Yogurt is probably the easiest homemade dairy product you can make without yogurt production machinery. 99% of aspiring amateur cheesemakers start with this. All you need is milk, some ready-made yogurt for yeast, heat and time.
What is yogurt?
Adding the yeast from older yogurt to milk is as follows: The bacterial cultures Lactobacillus bulgaricus or Lactobacillus acidophilus and Streptococcus thermophilus already present in yogurt produce lactic acid during the fermentation of lactose. Lactic acid lowers the pH, ie sour the milk, coagulates its proteins and acts as a preservative, since pathogenic microorganisms can not multiply in an acidic environment. The partial digestion of milk protein by bacteria is what makes yogurt more digestible than milk and yogurt production machinery easier to use.
The raw material
Yogurt can be made from any type of milk or you can make combinations. Cow, sheep, goat. Sheep’s milk yogurt is very tasty and with a solid texture. Goat’s milk has a more special taste and is used alone or mixed with sheep’s or cow’s milk. Cow’s milk gives yogurt with inferior taste and density. Whichever you choose, prefer it to be full of fat for a fuller taste and texture. If you can find milk from a breeder you will make the most delicious yogurt you have ever eaten. Milk must be freshly milked, clean, free of foreign matter and from healthy animals.
Yeast is considered a quantity of ready-made yogurt. What we need to make yogurt are living microorganisms to ferment the milk. These microorganisms are provided by a certain amount of older yogurt, which already has them in it. The amount of yogurt is about 3% of the total amount of milk.
You will need:
- 4.5 lt fresh milk
- 1 cup of yogurt about 200-220 gr
- Laboratory or kitchen thermometer
- A pot
- Yogurt jars with lids (glass or plastic that can withstand high temperatures)
- 1 large jar (to fit 1 cup of milk and the prepared yogurt together)
- Ice and cold water (eg in the sink or in a large basin)
- A portable refrigerator
Sterilize the large jar, jars and lids in a saucepan of boiling water for 5-10 minutes, with the lid closed.
Put the milk in another pot and heat it over medium heat. Simmer until it reaches a temperature of 85-90 ° C, for 15-20 minutes or 95 ° C for 3-5 minutes, thermometing and stirring constantly. Once you reach your temperature and the desired time to stay in it, withdraw the pot from the fire and immediately immerse it in the sink with cold water. Cool the milk to 50-55 ° C, always with your eyes on the thermometer. Once you reach the desired temperature, take the pot out of the sink with the cold water and set it aside.
Yogurt production machinery
Remove 1 cup of hot milk, put it in the sterilized jar and add the yogurt. Mix it lightly to melt well in the milk. Pour the yeast into the pot with the rest of the milk (which you have kept at 50 ° C) and mix well so that the yeast goes everywhere. Once the mixture is homogenized, divide it into sterile cups. Cover them immediately with their lids and tighten them.
Pour the water heated to 55 ° C into the portable refrigerator. When it gets the temperature from the walls of the refrigerator it will have gone to 50 ° C. Heat the water and if it is at 50 ° C, immerse the jars inside, with the lid out of the water. Close the lid of the refrigerator and leave it in a warm place for 3 hours. Do not disturb it or shake it from its position at all.
Many factors contribute to the success or failure of your homemade yogurt. Some of them are:
Good sterilization technique. This means proper technique of heating and cooling the milk, good cleaning and sterilization of the utensils used and aseptic technique when handling the milk.
Even pasteurized milk is not completely sterile from microorganisms, but it contains a number of bacteria, which can affect the taste of the final product or prevent the proper fermentation of milk in yogurt. Boiling and cooling our milk ensures a good result.
The bacteria I mentioned above are thermophilic, which means they love the heat and need it to multiply. Our bacteria require a temperature of at least 50 ° C to do what they should. At 50 ° C, the action of other pathogenic microorganisms is inhibited. But be careful because higher temperatures, eg 55 ° C, can kill our bacteria and we can never make yogurt. That is why the thermometer is necessary.
Some recipes may require lower temperatures. Also, do not open the yogurt package until it is time to put it in the milk.
Yogurt is preserved due to its acidity, which prevents pathogens from multiplying. If you paid close attention to the cleanliness during the preparation, if the cups you put in the yogurt were sterile and the lids were tightly closed, the product will be kept for 1-2 months in the refrigerator. After this time, and if you have not consumed it, a layer of white mold may form on the surface. You can remove it with a spoon and use it in your cooking safely. It is not pathogenic.