When freshly made tofu becomes sour within a few hours, the primary cause is rapid bacterial growth.
The two most critical factors are high temperature and poor hygiene conditions during production, handling, or storage.
Main Causes of Rapid Tofu Spoilage
1. High Ambient Temperature (Primary Cause)
Tofu contains a high level of protein and moisture, making it an ideal environment for bacterial growth.
In warm conditions—especially during summer—leaving tofu at room temperature allows bacteria to multiply rapidly, causing the tofu to spoil and develop a sour taste within hours.
2. Poor Sanitation of Equipment and Tools
If tofu-making equipment, cloths, molds, or containers are not thoroughly cleaned and disinfected, residual bacteria can contaminate the tofu during production. Even a small amount of contamination can significantly shorten shelf life.
3. Issues During the Coagulation Process
The coagulating agents used in tofu production (such as calcium sulfate or brine) and the water supply must be clean and food-grade.
Impure coagulants or contaminated water may introduce unwanted microorganisms into the tofu.
4. Inadequate Cooling After Production
Freshly produced tofu retains a high internal temperature.
If it is not cooled quickly and sufficiently, the remaining heat provides favorable conditions for bacterial growth, accelerating spoilage.
Effective Solutions to Prevent Tofu from Turning Sour
1. Rapid Cooling and Refrigeration
After production, tofu should be cooled as quickly as possible and transferred to cold storage immediately. Lower temperatures significantly slow bacterial activity.
2. Strict Hygiene Control
All equipment, tools, molds, cloths, and containers that come into contact with tofu must be thoroughly cleaned and disinfected.
Maintaining hygienic production conditions is essential for extending shelf life.
3. Storage in Light Salt Water
Soaking tofu in boiled and cooled water with a small amount of salt, then storing it under refrigeration, can effectively inhibit bacterial growth and extend freshness.
