Tempeh is a natural, fermented food, preserved by the action of a special fungus that adds nutrients and probiotics.
However, as with many cheeses, the natural presence of this fungus can make some people wonder if their tempeh has gone bad or if it’s still safe to eat.
So, does tempeh go bad? The answer is yes. It’s important to be able to tell the difference between the good mold and bad mold and know when tempeh is no longer safe to eat.
Read on to learn more.
Table of Contents
Can Tempeh Go Bad?
So, does tempeh expire? Yes it can, which can result in it going bad.
But if it’s improperly stored, or simply gets too old, tempeh can go bad and should be discarded.
How Do You Know if Tempeh is Bad?
Let’s go over three key signs that help you tell that your tempeh has gone bad.
It Smells Bad
Tempeh usually smells like mushrooms and may smell funky or cheesy, but should never have a smell of ammonia, acetone, or alcohol.
If you catch a very faint smell that resembles ammonia, but the tempeh seems otherwise okay to eat, it is probably safe to eat that day or the next, but should be discarded after that.
The Texture Is Off
Tempeh should have a firm, consistent texture throughout the cake. It often resembles densely-packed nougat or a firm cheese.
If it’s crumbly and falls apart, or is mushy or slimy, it should be discarded.
Tempeh may be a smooth, white color, or have grey patches. You may even find tempeh with black spots.
If you find that your tempeh is black, it may get even blacker over time. This is especially the case if it’s been exposed to air.
However, good tempeh should never have green or blue mold or fuzzy patches, or hints of a pink color. That’s a bad mold that should be discarded.
If you’re buying packaged tempeh from a manufacturer and it is completely covered with black mold, it may be a sign that the packaging was not completely sealed and air-tight.
Check the “sell-by” date and consider choosing a package with more of a white color with grey or black spots or patches.
While black mold is a normal part of the fermentation process, it can sometimes be a sign of improper packaging.
Can You Eat Tempeh with Black Mold?
Yes, the fungus that creates tempeh naturally turns black over time because it has living organisms that continue to grow.
The Rhizopus fungus in tempeh produces white filaments and then turns grey and eventually black as it matures and starts to reproduce.
If the tempeh still smells good and has a good texture, it is fine and safe to eat.
The presence of black mold may sometimes give your tempeh a stronger, more intense flavor.
If you prefer, you may want to shave off the outside layer of your tempeh to remove some of the black exterior and expose more of the white interior.
Good Mold vs. Bad Mold on Tempeh
Because tempeh is fermented with a fungus, the spores and mycelium are an essential part of the process.
However, it may sometimes be difficult to distinguish the fermentation fungus of tempeh from other molds and fungi that mean it has gone bad.
Read on to the next sections for my quick guide to good mold vs. bad mold on tempeh.
Good Mold on Tempeh
Good mold to expect on tempeh includes:
White fuzzy fibers. The Rhizopus fungus that ferments tempeh grows with white mycelium, which looks like fuzz or fibers. Over time, these fibers bind the soybeans together into a firm, white cake with a solid texture.
Grey fuzz or patches. Unless it is pasteurized, tempeh continues to slowly ferment after it is finished. While the white fibers are part of the growth stage of the Rhizopus fungus, grey fuzz or patches indicate the mature stage of progression. Because fermentation is not stopped completely, it is normal for the outside of tempeh to develop grey mold over time.
Black spots or patches. When Rhizopus is mature and ready to reproduce, it develops black spots or patches, especially if it has been exposed to air. These black dots are the sites where the fungus will grow new spores and spread, and is a normal stage of the maturation process.
Finally, pay attention to grey or black mold on the inside of your tempeh cake.
Good tempeh should have the white mycelium completely surrounding each soybean and binding them together.
If there are gaps and spaces inside tempeh, or if there are grey or black patches inside the cake, it means the tempeh is old and air has been allowed to reach the interior.
If it still smells okay, it should be eaten soon.
Bad Mold on Tempeh
Bad mold on tempeh is basically fuzz or spots that are any other color than white, grey, or black.
Some of the things to look out for are:
Green fuzzy patches. Aspergillus is a common household mold and you may have seen it on bread. It is usually green with grey edges and should never be eaten.
Blue mold. The only food with blue mold that is safe to eat is bleu cheese. Bleu cheese is made with a specific variety of fungus that is safe (and delicious) to eat, but household molds that are blue in color are always a bad sign.
Pink tint. A pinkish color is a sign of bacterial contamination, rather than a mold or fungus. If you see a pinkish discoloration, discard your tempeh.
Although tempeh is a fermented food, and fermentation is an excellent way to preserve foods and make them last longer, tempeh does go bad over time.
It can also become contaminated with unwanted molds or bacteria, which will not have the distinctive color and flavor of the fermenting fungus of tempeh.
Be attentive to expiration dates and always smell and feel tempeh before using it
Because tempeh has a naturally slightly funky smell and is made with a beneficial fungus, it may take a little practice to distinguish good mold from bad mold on tempeh.
When in doubt, discard old tempeh and make sure to use a fresh product.