30-60 minutes. According to Kyushu Drunk Catering Network, the semi-finished mutton offal needs to be boiled for 30-60 minutes, because the semi-finished mutton offal needs to be boiled for a few minutes before adding other seasonings. Mutton offal generally includes sheep heart, sheep lung, sheep belly, sheep intestines and so on. It needs enough heating to destroy the bacteria and viruses in it, and at the same time make the mutton offal more soft and rotten.