To boil soy milk tofu, it typically takes around 10 to 15 minutes. This duration is sufficient to ensure that the tofu is thoroughly cooked and the soy milk has been well incorporated into the tofu. The exact time can vary slightly depending on the size and density of the tofu blocks, as well as the temperature of the boiling water.

The reason for this boiling process is to activate the soy milk's proteins, which helps to firm up the tofu and enhance its texture. Additionally, boiling the tofu helps to remove any impurities or excess soy milk that may have been used during the tofu-making process. According to a study published in the Journal of Food Science, the boiling process can also improve the digestibility of the tofu by breaking down some of the complex proteins into smaller, more easily digestible peptides (Wang et al., 2018). This makes the tofu more accessible to the body's digestive enzymes, potentially leading to better nutrient absorption.