Tofu that is water-packed is not airtight. Consequently, air and bacteria are in the package or can easily get into it. Because tofu is a moist, high-protein food, bacteria are attracted to it and joyfully take up residence and rapidly proliferate. When tofu is cooked, this foodborne bacteria is destroyed. However, when tofu is added to a recipe "raw," as in a tofu salad or spread, the bacteria are alive and well and growing. Many people who eat "raw" tofu and get gassy or a tummy ache afterwards (or worse) sometimes think they are allergic or have a sensitivity to tofu. That's rarely the situation; true food allergies of any kind occur in only about 1% of the adult population. Typically it is a case of mild food poisoning.

We cannot see or smell foodborne bacteria, so there is no way to detect it on "raw" tofu. Most people think that if tofu looks and smells fresh, it's okay to eat it "raw" -- so they do. When they suffer the consequences, they usually don't make the connection between bacteria on their tofu and their short-lived illness.

To destroy this bacteria, tofu that is to be eaten "raw" should be rinsed and boiled in fresh water or steamed for 5-10 minutes before using. To quick-chill it afterward, slice it into slabs and lay it in a single layer on a stainless steel, glass, or ceramic tray or plate in the refrigerator or freezer. When it is thoroughly cold to the touch, proceed with your recipe.

Tofu that is not water-packed but is already cooked and vacuum sealed or asepetically packaged does not need to be boiled or steamed before using, nor does tofu that will be cooked in a recipe. This step is only necessary for tofu that is water-packed and will not be cooked.