The bad smell indicates that the food has begun to deteriorate and mildew, so it can't be eaten. If you eat moldy and moldy food, it will be harmful to your health. Deteriorated food first has unacceptable sensory characteristics, such as pungent smell, abnormal color, sour taste, tissue ulceration, mucus pollution and so on. When food goes bad, protein, fat, carbohydrates, vitamins and inorganic salts in food will be destroyed and lost, and food will lose its nutritional value. Food corruption also increases the chances of pathogenic bacteria and toxic molds. Eating spoiled food can cause adverse reactions and even poisoning. There are more and more reports and food poisoning incidents, such as histamine poisoning caused by some fish spoilage, adverse reactions and poisoning caused by fatty acid spoilage products, nitrosamine poisoning caused by food spoilage and so on. Therefore, you must not eat bad food.