"Old Lady Cheng" bean curd is another brand food in Maoba Township, Lichuan City. Traditional fermentation technology is used to make tofu. The following is related to fermentation technology.

A. Mucor, Aspergillus oryzae and other microorganisms should be used to make tofu milk, and the fermentation process needs appropriate temperature. Too high or too low temperature will inhibit or kill the growth and reproduction of microorganisms, so controlling the temperature during fermentation is one of the key conditions.

B, the fermentation process should be sealed as much as possible to prevent the entry of miscellaneous bacteria, which does not meet the meaning of the question.

C, according to a, fermentation is not necessarily done by yeast, which does not meet the meaning of the question.

D, after the tofu is cooked, it should be cooled to a suitable temperature before inoculation. If the temperature is too high, it will kill microorganisms on the inoculum.

So choose: a