There are several simple tools for raising lactic acid bacteria in free grazing: a small funnel, a small basket and a closed glassware. The small funnel is used for "fishing", the small basket is a "bathtub" and the glassware acts as a "fermentation factory". What Helen has to do is to pour lactic acid bacteria and fresh milk into glassware before going to bed every day. After a night of "free grazing", the milk became thicker and more sour the next day due to the continuous excretion of lactic acid bacteria. Lactic acid bacteria SPA Lactic acid bacteria have had enough to eat and drink. Helen must scoop out the lactic acid bacteria in the milk with a colander. After the milk is drained, pour them into a clean bowl and pour cold water (cold water must be used, and hot water will burn the lactic acid bacteria) to bathe the lactic acid bacteria. While washing, you have to "massage" by hand. Gestures should not be light or heavy-light, unclean and easy to stink; If it is heavy, it will pinch the lactic acid bacteria to death. It is said that the crushed lactic acid bacteria will float to the surface, which is "terrible". Baby mushrooms after a bath live like sago in sago dew, chubby and very cute. Lactic acid bacteria will slowly "grow up". If properly reared, they will multiply more and more. Excess lactic acid bacteria can be given away or swallowed in one gulp-once these little guys enter the stomach, they will settle down there safely, inhibit the reproduction of bad bacteria, remove abnormal fermentation in the intestinal tract, maintain the ecological balance of bacteria in the body and increase human immunity. Helen said that since she started raising these "babies", she obviously felt much more comfortable. Can I drink homemade yogurt? Experts said that although Helen was very happy, the reporter still had many questions. Is there a scientific basis for fermenting milk with lactic acid bacteria raised at home? Is it hygienic? What's the difference between fermented milk and spoiled milk? To this end, the reporter specially consulted Dr. Xu, the "yogurt expert" of Bright Dairy Technology Center. Reporter: Where do lactic acid bacteria come from? Dr. Xu: A long time ago, herders liked to hang skins full of milk on horseback. When skin is heated by friction, milk naturally ferments. The weather is hot, the air is dry, and the moisture of fermented milk is evaporated, so there are fragments of lactic acid bacteria. They are easy to survive and reproduce quickly, so lactic acid bacteria can be preserved. Reporter: What's the difference between your own yogurt and what you bought in the supermarket? Dr Xu: First of all, the strains of lactic acid bacteria will be different. The number of domestic lactic acid bacteria is small, and it can only be propagated by itself, which belongs to "generation bacteria". However, there are many kinds and quantities of lactic acid bacteria in the factory. Fermented in milk is "direct-feeding bacteria", and the ingredients are more effective. It must taste different. Yogurt pays attention to taste, and its consistency and acidity are related to the fermentation process. If you ferment yourself, if you don't master the time and temperature well, the yogurt will be too sour to eat. Reporter: Is homemade yogurt hygienic? Dr. Xu: It depends on whether the instruments used are clean and whether the environment of milk fermentation can be ensured to be sterile. Milk is rich in nutrition, which is more conducive to the growth and reproduction of bacteria than human body. If disinfection and sterilization are not done well, many bacteria harmful to human body in the air will quietly multiply in milk. When manufacturers make yogurt, milk does not touch the air during fermentation, and all utensils are completely sealed and sterilized at high temperature, but the production at home is not so elegant. Therefore, it is ok to play occasionally. If you drink it every day, it is difficult to guarantee that other "bad bacteria" will be mixed in milk one day, which will lead to diarrhea. In addition to this kind of domestic lactic acid bacteria, I also heard that some people fermented milk with lactic acid bacteria slices, and some even mixed the bought ready-made yogurt with milk to make yogurt. These principles are correct, but the problem is the same as mentioned above, that is, hygiene is not up to standard.