First of all, it is important to grasp the quantity. Bittern is not like gypsum. A little more will cause great changes in tofu pudding. This is to be taught by someone. This is very important. You'd better find a master to learn.

Also, when you say that the tofu is not tight in the middle, it may be that your tofu is too old, and the pressure is not enough when pressing the tofu, and the tofu water is not completely discharged. You should tender the tofu pudding first and press it tightly. Don't be too tender. If you can't grasp it well, just press it tightly according to your previous method.

Another way is that some people add bean flour to the bean curd, which is the thickening powder for cooking at ordinary times, so it looks more delicate.