Introduction: Making yogurt at home has become a trend these days. In this issue, I've compiled the most common questions people have when making homemade yogurt, hoping to be of some help to everyone.
Which is better for culturing, yogurt starter powder or store-bought yogurt? Both work. When using yogurt starter powder, you are adding freeze-dried cultures, which can "wake up" and become active in a warm environment. When using store-bought yogurt, be sure to buy the freshest possible refrigerated yogurt, because as storage time increases and the temperature rises, the number of live bacteria will continuously decrease, affecting the quality of the yogurt you make. Note that yogurt sold at room temperature should not be used as a starter.
When buying yogurt starter powder, is it better to have more cultures? The basic requirement for making yogurt is to have enough Lactobacillus bulgaricus (L) and Streptococcus thermophilus (S), so a starter powder containing these two basic cultures is sufficient. Other probiotic bacteria, such as Lactobacillus acidophilus (A), Bifidobacterium (B), and certain strains of Lactobacillus casei (C), have been proven to be beneficial to health if they can colonize the human large intestine. However, it is difficult to get live Bifidobacterium through the typical home yogurt-making process. Therefore, you shouldn't have too high expectations for the probiotic bacteria in the starter.
If using store-bought yogurt as a starter, how much should be added? Generally, it's appropriate to add about 10% of the total volume as the starter yogurt. For example, to ferment 500 grams of milk, you would use 50 grams of starter yogurt.
Can the yogurt I made myself be used as a starter for the next batch? If you use a purchased starter culture to make yogurt, it can be used as a starter for another two to three batches. If you use store-bought yogurt as the starter, it can be used for one more batch at most. When using yogurt from the previous batch as a starter, be sure that the yogurt has a pure taste and is fresh enough.
How should the milk be prepared before making yogurt? Before making yogurt, if you are not using milk freshly poured from a sterile Tetra Pak carton, it's best to heat the raw milk to 60°C~80°C. It shouldn't boil, but this temperature is high enough to kill most bacteria. Then, cool it down to 40°C (it should feel slightly hot to the touch, but not uncomfortably so) before inoculating. The containers and spoons used for making yogurt should also be scalded with boiling water, or you can place a spoonful of water in the yogurt container and microwave it to use the steam to kill the microorganisms on the surface, thereby minimizing the chance of contamination.
Can low-fat yogurt be made at home? Low-fat yogurt is very easy to make. Just use skim milk powder or low-fat milk as the raw ingredient and add the culture for normal fermentation. Lactic acid bacteria are well-adapted to a low-fat environment.