Whether to use cold water or hot water for stewing pork bones depends mainly on whether you want to eat the meat or drink the soup. If you want to eat the meat, it's best to use hot water for stewing, because the meat stewed with hot water is delicious and tasty. Conversely, the broth stewed with cold water is delicious and flavorful. Why is this? Because stewing pork bones with hot water from the beginning causes the surface of the bones to be suddenly exposed to high temperatures, causing the protein in the outer layer of meat to coagulate rapidly. This prevents the protein in the inner layer from fully dissolving into the soup, so the soup's flavor is naturally not as rich as when cooked with cold water.
Chinese Yam and Corn Bone Soup
It should be noted that if you find the water level is low during the stewing process, do not add cold water lightly. The reason is similar to the one mentioned above. If water needs to be added midway, it should be hot water; never add cold water.
It should be noted that salt should not be added too early when making the soup, because salt has a permeating effect that easily draws moisture out of the ingredients, which accelerates the coagulation of protein and affects the soup's flavor. In addition, soy sauce should not be added too early either. The amount of seasonings like scallions, ginger, and cooking wine should also be appropriate; do not add too much, as this will also affect the natural umami of the soup itself.