Core Tip: Nowadays, many people make yogurt at home. What should be noted when making homemade yogurt?
Associate Professor Fan Zhihong from the Department of Nutrition and Food Safety at the College of Food Science, China Agricultural University, stated that to make yogurt, *Streptococcus thermophilus* and *Lactobacillus bulgaricus* are essential. The two help each other, promoting acid production speed and allowing the yogurt to set properly. Without these two bacteria, it is difficult to make yogurt or the flavor may be unacceptable. If you want to add other probiotic bacteria, you must mix them with these two in the proportions recommended by the instructions.
If you are not buying a commercial starter, you can use your favorite yogurt from the market as the starter. The recommended ratio for using finished yogurt as a starter is 1 part yogurt to 10-20 parts milk. The yogurt made can only be used as a starter one more time. If done more times, the yogurt will set more and more slowly, the flavor will deteriorate, and it may also become unsafe due to contamination with other bacteria.