2. Moldy yam is easy to produce many bacteria. The starch and water in yam will rot after being infected by bacteria, which will greatly reduce the nutritional value and even damage human health. Yam has high edible value and medicinal value, and has the effects of invigorating spleen and regulating stomach, invigorating lung qi, tonifying kidney and replenishing essence. Proper consumption can treat abdominal distension, loss of appetite, dyspepsia, nocturnal emission, frequent urination, impotence, soreness of waist and knees, premature ejaculation and other symptoms.