After learning the application of traditional fermentation technology, a classmate wants to redo the experiment at home to further verify what he has learned. The following is about him.

A, when making fruit wine in the experiment, it is necessary to inoculate strains, and it is necessary to introduce sterile air first, and then seal the fermentation. A is wrong;

B, yeast can be separated by dilution coating plate method or plate scribing method, but yeast can only be counted by dilution coating plate method, not by plate scribing method. B is correct;

C, when making sufu, the tofu with hairy enzymes should be sealed when adding salt, which is to inhibit the growth and reproduction of microorganisms, C error;

D, the acetic acid strains are preserved by a temporary preservation method, and the culture medium needs to be transferred every 3-6 months. When the strain is preserved in this way, it is easy to be polluted or mutated, and D is wrong.

Therefore, choose: B.