Making yogurt at home has become a trend these days. In this issue, I've compiled the most common questions people have when making their own yogurt, hoping it will be helpful to everyone.
Q1: Which is better to use as a starter, yogurt powder or store-bought yogurt?
Both work. When using yogurt powder, you're adding freeze-dried cultures that can "wake up" and become active in a warm environment. When using store-bought yogurt, be sure to buy the freshest refrigerated yogurt you can find, as the number of live bacteria decreases over time and with rising storage temperatures, which can affect the quality of your homemade yogurt. It's important to note that you should not use yogurt sold at room temperature as a starter.
Q2: When buying yogurt powder, is it better to have more types of cultures?
The basic requirement for making yogurt is to have enough Lactobacillus bulgaricus (L) and Streptococcus thermophilus (S). Therefore, a powder containing just 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 shown to be beneficial to health if they can colonize the human large intestine. However, it is difficult for the typical home yogurt-making process to produce live Bifidobacterium. Therefore, you shouldn't have overly high expectations for the probiotic bacteria in the culture.
Homemade Yogurt
Q3: When using store-bought yogurt as a starter, how much should I add?
Generally, it's appropriate to add about 10% of the total milk volume as a starter. For example, to ferment 500 grams of milk, you would use about 50 grams of store-bought yogurt.
Q4: Can I use my homemade yogurt as a starter to make a new batch?
If you use a purchased culture to make yogurt, you can reuse it as a starter for two or three more batches. If you use store-bought yogurt as a starter, you can reuse it for at most one or two more batches. When using yogurt from a previous batch as a starter, it's important that the yogurt has a pure taste and is fresh enough.
Frozen Yogurt
Q5: 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. This will kill most bacteria without bringing it to a boil. Then, let it cool down to 40°C (it should feel slightly hot to the touch, but not uncomfortably so) before inoculating. The container and the spoon you use for adding the culture 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 hot steam to kill microorganisms, thereby minimizing the chance of contamination from other bacteria.
Q6: Can I make low-fat yogurt at home?
Low-fat yogurt is very easy to make. Just use skim milk powder or low-fat milk as the ingredient and add the culture for fermentation as usual. The lactic acid bacteria are well-adapted to a low-fat environment.
Yogurt Cake