Hi, this recipe comes from Christopher Tan so I can't say for certain but I believe it might have something to do with ensuring an accurate amount of liquid is added to the recipe every time. So, if the amount you get from squeezing the tapioca adds up to less than 230g, you know that you need to add an extra 40g of water to the juice. Mr Tan also talks about the science of making kueh in his book so there might be some other reason for it. All I know is that this recipe results in great tasting Kueh Bingka Ubi 😀
