1. Normal fermentation: If red yeast is added to tofu during the production process to make tofu, there will be a layer of red mold on the surface, which is normal. Its monascus is a kind of monascus rice in which the mycelium of Aspergillus fungi parasitizes on japonica rice. It does not contain toxic substances, but also has the effects of invigorating spleen, promoting digestion, promoting blood circulation and removing blood stasis, and can be eaten continuously.
2. Deterioration: If red yeast is not added in the process of tofu production, other colors such as yellow and black will appear besides red, and moldy tofu will also emit obvious odor. Bacteria and fungi will multiply in high temperature or humid environment for a long time, which will destroy the nutrients and produce a lot of toxic and harmful substances. Tofu has gone bad and can't be eaten any more. If you eat spoiled tofu, you will have bad symptoms such as abdominal pain, diarrhea and vomiting.
The red color of tofu fermentation is caused by microbial activities. This phenomenon is very common in food fermentation, mainly because of the pigment produced by microorganisms during the propagation of tofu. Among them, the common red mycelium is a kind of mold, also known as fungal cocci. This mycelium usually produces a substance called mannitol, which will form a red compound in the reaction, which will cause tofu to turn red. In addition, there are other factors that may cause tofu to turn red, such as chemical reaction and physical action. In short, in the process of food processing and storage, we should pay close attention to food quality and safety issues and take timely measures to protect food from pollution or deterioration.