When making tofu, nigari water (magnesium chloride) is added to soy milk to curdle it.
In my personal experience, adding the nigari very slowly (over the course of tens of minutes) produces soft tofu with a larger volume. Adding the nigari fast (over only a few minutes) produces tofu of a smaller volume for the same amount of soy milk used, but the tofu is firmer.
However, this is only my anecdotal experience, so is there any information available from a reputable source about how the speed of nigari addition affects the resulting tofu? And if so, is there an explanation for why this is the case?