Tofu is a nutritious soy-based food that can spoil quickly if not handled properly after opening. Knowing how to identify signs of bad tofu is important to avoid accidentally eating spoiled tofu. This article will cover indicators of fresh versus rotten tofu, proper storage methods, what causes tofu to go bad, if moldy tofu can be safely eaten, and how long tofu lasts refrigerated or frozen after opening. Using these guidelines can help ensure you are able to fully enjoy tofu before it deteriorates.
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Signs of Fresh Tofu
Here are some signs that indicate tofu is still fresh and safe to eat:
- Firm texture – Fresh tofu is resilient when pressed and holds its shape when lifted.
- Clear liquid – The packing liquid is clear, not cloudy or colored.
- Neutral aroma – Fresh tofu has a mildly bean-like smell. No sour, ammonia, or yeasty odors.
- White color – The tofu has a fresh white hue. No darkening or unnatural colors.
- Smooth surface – The tofu has a smooth look with no cracks, holes or separating.
- Intact packaging – The packaging is still sealed properly with no leaks or punctures.
- Use by date – The tofu is consumed before the expiration or use-by date printed on the package.
Tofu that is mushy, crumbly, discolored or foul-smelling is past its prime and potentially spoiled.
What Causes Tofu to Spoil?
There are a few main factors that can lead to tofu spoilage:
- Bacteria – Common foodborne pathogens like Salmonella, Listeria, Staphylococcus and Bacillus cereus grow rapidly in perishable soy products.
- Mold – Fungi thrive in refrigerated environments with moisture. Rhizopus, Mucor, and Penicillium molds can develop.
- Yeasts – Yeasts ferment sugars into alcohol, gases and acids. This alters the texture and smell.
- Temperature abuse – Heat greatly accelerates spoilage reactions. Storing open tofu unrefrigerated promotes microbial growth.
Properly refrigerating tofu after opening inhibits microbial growth to maintain freshness and shelf life.
Key Point: Bacteria, molds and yeasts can proliferate in old, warm tofu leading to spoilage.
6 Signs That Your Tofu Is Bad
Like any perishable food, tofu has a limited shelf life and can spoil if not handled properly. There are clear indicators you can look for to determine if your tofu has gone bad.
How to Tell If Tofu Has Gone Bad? Check your tofu for these visible signs of spoilage before eating:
1. Slimy Texture
Fresh tofu has a firm, creamy texture. As it starts to spoil, the surface becomes sticky, shiny and slimy.
A glossy sheen and sticky slime on the tofu is caused by bacteria breaking down proteins. Discard any slimy tofu.
Key Point: Tofu develops a slippery, glossy texture and slime when contaminated with bacteria.
2. Off Odors
Good fresh tofu has a mild, neutral smell. As it goes bad, an increasingly unpleasant sour or rancid odor develops.
Some describe the stench of spoiled tofu as like ammonia, rotting vegetables or fermented soy. Foul odors mean the tofu has gone bad.
Key Point: There is a distinct sour, “off” smell when tofu goes bad.
3. Mold Growth
Growth of mold on the surface or inside the packaging indicates the tofu has spoiled. You may see dry, fuzzy white and black mold.
Do not eat any moldy tofu. Mold can spread toxins deep into the soy curds invisibly. Promptly discard all moldy tofu.
Key Point: Any mold growing on or inside the tofu packaging means it is bad.
Fresh tofu is typically white to pale yellow. As it starts to go bad, the color changes to an unnatural grey, brown, pink or yellow-green color.
These dull, abnormal colors mean deterioration and bacterial overgrowth. Avoid eating any discolored tofu.
Key Point: Tofu turns from white/pale yellow to grey, brown, yellow-green or pink as it spoils.
5. Weird Spongy Texture
High levels of bacterial growth can cause tofu to develop a strange sticky, spongy texture as it spoils. Gas bubbles from microbes get trapped in the soy, making it look foamy.
Sponginess, holes or foamy appearance signals severely spoiled tofu that should be thrown away.
Key Point: Foamy, mushy or spongy texture means the tofu has gone bad.
6. Sour Taste
Fresh tofu has a relatively bland taste. Spoiled tofu develops a sharp, unpleasant sour flavor as bacteria produce acids during growth.
An acidic, tangy taste means the tofu has gone “off”. Rancid flavors indicate bacterial contamination.
Key Point: Spoiled tofu tastes noticeably more sour due to lactic and acetic acid production during bacterial fermentation.
How to Store Tofu?
Tofu is a versatile protein-rich food made from soybeans. However, like many perishable foods, tofu requires proper storage methods to maximize its shelf life and prevent spoilage.
How Long Does Tofu Last?
With proper refrigerated storage, packaged tofu typically lasts:
- Unopened – 7 to 10 days past the expiration date.
- After opening – 3 to 5 days
Discard any tofu that develops signs of spoilage, even if within the date on the package. Freezing can extend the shelf life 6-8 months.
Key Point: Refrigerated tofu keeps 1-2 weeks past the package date when unopened. Consume within 3-5 days of opening.
Because tofu is highly perishable, proper refrigeration is essential:
- Keep tofu refrigerated at 40°F or below at all times for food safety and to extend shelf life.
- Leave tofu in its original water-filled packaging until ready to use. The water preserves freshness.
- Once opened, transfer unused tofu to an airtight container filled with fresh water. Make sure all pieces are fully submerged.
- Change the water daily to keep it cool and fresh.
- Eat refrigerated fresh tofu within 3-5 days for best flavor and texture.
Constant cold temperatures maintain both the safety and quality of fresh tofu. Keeping it immersed in water prevents drying out.
Tofu can also be frozen to extend its shelf life:
- Drain water from tofu package and cut tofu into desired shapes and sizes.
- Arrange tofu pieces in a single layer on a sheet pan or baking dish. Place in freezer.
- Once frozen solid, transfer pieces to labeled freezer bags or airtight containers. Remove as much air as possible.
- Return to freezer and store at 0°F. Use within 6 months for best quality.
- Thaw frozen tofu overnight in the refrigerator before using. Pour off any liquid.
Freezing gives tofu a firmer, chewier texture. It also enables longer term storage.
Thawing Frozen Tofu
Always thaw frozen tofu gradually in the refrigerator. Avoid thawing at room temperature.
- Place still-wrapped frozen tofu on a plate or tray to catch any drips as it defrosts in the fridge overnight.
- After thawed, pour off any liquid that has accumulated from the freezing process.
- Use thawed tofu within 3-5 days for best freshness.
- Do not refreeze thawed tofu, as the texture deteriorates.
Slow refrigerator thawing preserves the quality of frozen tofu. Drain liquid before use.
Storing Tofu After Opening
Once opened, leftover fresh tofu should be handled properly:
- Cover the unused portion of tofu with fresh water in an airtight container.
- Make sure all surfaces stay fully submerged to prevent air exposure.
- Change the water daily to keep it cool and fresh.
- Eat within 3-5 days for best quality.
- For longer storage, freeze any remaining pieces using proper method.
Keeping opened tofu immersed in cold fresh water every day maximizes the refrigerated shelf life.
How Long Does Tofu Last Refrigerated?
When properly stored, tofu lasts:
- Commercial unopened package: 5-7 days past expiration date
- Commercial opened package: 5-7 days refrigerated
- Homemade tofu: 3-5 days refrigerated
So while the expiration date may allow 5-7 days extra leeway, consume opened tofu soon within this same timeframe for optimal freshness and flavor.
Common Tofu Storage Mistakes
Avoid these common food storage errors when handling tofu:
- Leaving tofu out unrefrigerated for over 2 hours
- Not changing water daily for stored opened tofu
- Storing in sealed packaging long term once opened
- Freezing and thawing incorrectly, resulting in spongy texture
- Assuming prepared tofu dishes like scramble can be left out overnight
Proper, diligent storage and freezing techniques help prevent spoilage and foodborne illness.
Can You Get Sick From Eating Spoiled Tofu?
Yes, consuming tofu that has gone bad can potentially cause foodborne illness. The biggest risks are from bacteria:
Pathogens like Salmonella, Staphylococcus aureus, Bacillus cereus, Clostridium botulinum and Listeria can multiply quickly in contaminated tofu, especially when temperature abused.
If ingested, these bacteria may lead to vomiting, diarrhea, abdominal cramps, headache, nausea and weakness starting 12-72 hours after consumption.
Serious infection is more likely in sensitive groups like children, elderly, pregnant women and immunocompromised persons. Use caution and discard tofu at the first signs of spoilage.
Key Point: Bacteria present in spoiled tofu can cause foodborne illness if consumed.
Is It Safe to Eat Moldy Tofu?
It is not recommended to knowingly eat tofu that has mold growing on it. Here are some reasons why moldy tofu should be fully discarded:
- Mold can penetrate deep into the tofu, beyond just the visible mold on the surface. Eating may introduce mold into the digestive system.
- Molds release allergenic spores into the surrounding air when disturbed. Inhaling spores poses respiratory risks.
- Powerful aflatoxins or other mycotoxins may form on moldy tofu that cooking temperatures don’t destroy.
- Mold contributes unpleasant textures and flavors. The tofu is unpalatable.
- Even a small amount of mold indicates the tofu should be discarded or composted.
With perishable products like tofu, it’s impossible to simply cut away just the visibly moldy parts safely. So entire packages or pieces with any mold should be discarded. Don’t take risks by eating moldy tofu.
How To Store Leftover Tofu Dishes
Storing cooked tofu meals properly also helps prevent bacterial growth. Follow these tips:
- Refrigerate any unused portion of cooked tofu dishes within 2 hours.
- Divide into shallow airtight containers to chill quickly. Avoid large dense masses.
- Use leftovers within 3-4 days for safety and optimal quality.
- Check for any signs of mold, sliminess or off-odors. Discard if detected.
- Discard tofu stir-fries, soups or other dishes if older than 4-5 days, even if no spoilage is visible.
Rapidly chilling cooked tofu leftovers inhibits further bacterial proliferation, keeping it safe to eat again later.
Frequently Asked Questions
How long can open tofu sit out unrefrigerated?
An opened package or cut tofu should not sit out more than 2 hours before spoilage can occur. Always refrigerate opened tofu within 2 hours. Discard if left out longer.
Can you freeze tofu after opening?
It’s not recommended to refreeze previously frozen tofu after thawing or freeze opened tofu. This can increase risk of bacterial growth. Refrigerate opened tofu and use within 7-10 days.
Is it safe to eat expired tofu if not opened?
Unopened, commercially packaged tofu can often be safely consumed within 7-10 days past its printed expiration date. Check for off odors or appearance before consuming expired tofu.
Can moldy tofu make you sick if cooked?
It’s unsafe to knowingly consume tofu with mold, even if thoroughly cooked. Heat does not destroy hazardous mycotoxins and mold may be toxic. Always fully discard moldy tofu.
Why does tofu turn brown after opening?
Exposure to air causes oxidation that turns tofu tan or brown. While harmless, it indicates the quality is going downhill. Consume discolored tofu within 3-5 days.
Knowing how to identify signs of spoiled versus fresh tofu prevents accidental consumption of bad tofu. Refrigerate opened tofu promptly in an airtight container, and check for changes in texture, smell, color or mold. Understand proper storage temperatures and shelf life after opening. While freezing extends the expiration date, do not refreeze thawed tofu. Discard moldy or questionable tofu fully. Following these guidelines allows you to safely enjoy nutritious tofu at its best quality.