How To Tell When Tofu Has Gone Bad
Made from coagulated soy milk, tofu is a plant-based protein that has a longer shelf life than some of its meat or dairy-based alternatives. After all, where fresh milk can start to spoil within a week, shelf-stable varieties of soy milk will stay fresh for months on end. Even so, tofu will eventually spoil, and looking for certain signs will let you know exactly when it is past its prime.
The best way to gauge tofu's freshness is to simply look at it. While mold is an obvious red flag, so is any yellow discoloration. The latter is usually a sign of tofu that's begun to oxidize from exposure to air. The package that the tofu comes in shouldn't have puffed up either as this too is an indicator of spoilage. Be sure to observe the texture of tofu as well. Depending on its type, tofu can have a soft and silky or firm and spongey texture, but what it should never have is an oddly curdled appearance and a slimy feel to it.
Another sign is smell: Rancid stench wafting from the tofu is a sign that it needs to be tossed out. If your tofu has none of these telltale signs, but you're still concerned about its freshness, there's always the taste test as a last measure. Tofu has no real flavor of its own, so it definitely shouldn't taste sour: This is generally an indicator of tofu that's begun to ferment and spoil.
How long tofu generally stays fresh for
Most proteins such as beans, nuts, eggs, and even tofu have a best-by or use-by date rather than an expiration one (which is also different from a sell-by date). While expiration dates are an indicator of nutrition and effectiveness, tofu's best-by or use-by dates are indicators of its quality. So while tofu may not expire the way that some perishable items do, its taste, texture, and appearance can certainly change for the worse.
In general, unopened tofu that's still sealed inside its packaging will stay fresh for two to three months past the date written on it — and for four to six months if it's kept in the freezer (more on this later). Once opened, however, its shelf life shortens considerably, and it can go bad in as little as five days even when stored in the refrigerator, or within an hour or two at room temperature.
Tofu spoils even more quickly if it is frequently taken in and out of the refrigerator. Instead, a good way to increase tofu's shelf life once it's open is to cook all of it in one go rather than keep it raw. Prepped and cooked tofu will stay fresh for up to a week beyond its best-by or use-by dates in the refrigerator.
Store tofu properly to keep it fresh for longer
Storage has a direct impact on how long a perishable item will stay fresh or how quickly it will spoil. For example, tofu is found either in the refrigerated section of a grocery store or on a room-temperature shelf. Where you pick up your tofu from at the store will determine where it should be stored at home: Refrigerated tofu should be kept there even when unopened whereas room-temperature tofu is fine on the counter until you open it.
If you've opened the package but have leftovers and need to store your tofu in the fridge, there are a few steps to follow before you pop it into the refrigerator. Place the tofu in an airtight container and cover it with fresh water. Toss the water out and refill it with fresh liquid every day. Doing so will keep the protein moist until you're ready to use it all up.
On the flip side, tofu that's to be stored in the freezer needs to be thoroughly dried first. Dice the tofu into small cubes, press it with paper towels and some weight to get rid of extra moisture, and then place the cubes in freezer-safe boxes or bags. Move the tofu from the freezer to the refrigerator a day or two before cooking to defrost it. Frozen tofu does have a stellar rep for being especially spongey in texture, so that's always a bonus!