Various signs will tell you your tofu has spoiled and is unsafe to eat. Two key indicators are puffed up packaging and a sour smell, signaling the presence of bacteria and yeast.
Healthy tofu should be white or off-white, and any discoloration suggests degradation. To stay safe, do not consume tofu if you notice any shift towards yellowish or darker hues.
Another clear sign of spoilage is changes in texture. Sliminess is a tell-tale sign and occurs when microbial growth has escalated and compromised the tofu's structural integrity.
Mold is also a clear indication that it is no longer safe to eat. If your tofu displays fuzzy spots varying in color from white to green or black, dispose of it immediately.
To extend tofu's freshness, store it submerged in water in an airtight container and change the water daily. Alternatively, dice it into small pieces and store it in the freezer.